Dissertations / Theses on the topic 'Crassostrea – Diseases – Environmental aspects'

Use of antibiotics in the aquaculture industry for the control of bacterial infections in salmon has led to public concern regarding antibiotic residues in salmon tissue and the potential health risk this poses to humans. Oxytetracycline and Romet-30 are two common antibacterial agents utilized to control disease in the local finfish aquaculture industry of British Columbia, Canada. Many fish farms in British Columbia are located within close proximity to existing shellfish stocks. The potential for antibiotic bioconcentration and the production of bacterial resistance to the drugs in bivalves is a concern. The development of a solid phase extraction technique for these two drugs from Pacific oysters, Crassostrea gigas was accomplished. Analysis of whole oysters via HPLC revealed detectable levels of oxytetracycline and Romet-30 up to 4 weeks after antibiotic treatment at the salmon farm site. Oysters suspended in the salmon net pens and surrounding waters were sampled over a 5 month period. Concentration of oxytetracycline residues in oyster tissue reached a maximum of 0.11 ppm (n=2). Levels of sulphadimethoxine in oyster tissue reached a maximum concentration of 1.27 ppm (n=2). Maximum detectable concentrations of ormetoprim in oysters were 0.26 ppm (n=2). A controlled study investigating uptake and depuration of oxytetracycline and Romet-30 in the Pacific oyster revealed results similar to those described for the salmon farm. A flow through drug delivery system for the Pacific oyster was utilized over a ten day uptake and thirty day depuration period. Levels of oxytetracycline in whole animal tissue increased in a linear fashion (r²=0.984) over the uptake period. This indicates that the drug was bioaccumulated in the oyster reaching a maximum concentration of 10.72 ± 2.4 s.e. ppm (n= 3) on day 10 of uptake. Depuration of the drug was rapid. After thirteen days a concentration of 0.21 ± 0.04 s.e. ppm (n=7) was detected. The detection of Romet-30 in the uptake and depuration in the oyster was more erratic. Day 7 of uptake revealed a maximum concentration of sulphadimethoxine and ormetoprim of 1.092 ± 0.24 s.e. ppm (n=7) and 0.21 ppm (n=3) respectively. Depuration of Romet-30 was rapid. The concentration decreased to 0.029 ppm (n=3) by day 13. Condition indices of oysters sampled before and after antibiotic treatment indicated a significant increase (p<0.05) in condition index after treatment with medicated feed. A quantitative survey of bacteria associated with the gut of the oyster was performed. Relative numbers of endogenous bacteria were compared to oysters before and after antibiotic treatment. Numbers of bacteria significantly decreased (p< 0.05) following treatment.
Land and Food Systems, Faculty of
Graduate

American oyster (Crassostrea virginica) stocks on the East Coast in general, and in Chesapeake Bay in particular, have been in decline over the past half-century in large part due to Dermo disease, caused by the protist parasite Perkinsus marinus. Efforts to restore oysters for their ecological and economic value have centered on the development and use of hatchery-based seed selectively bred for disease resistance. Selective breeding could benefit from the incorporation of oysters from wild stocks that have developed "natural Dermo resistance", but few such stocks have been identified and verified. This dissertation describes reciprocal common-garden experiments carried out at two sites in each of the Gulf of Mexico and the Chesapeake Bay between fall 1999 and winter 2001. The experiments compared growth, disease intensity, and survival of seed from putatively disease resistant and susceptible populations in both the Gulf of Mexico and Chesapeake Bay. In the Gulf experiment, oysters from Gulf stocks showed increased survival and decreased disease intensity, determined by body burden analysis of parasite cell counts, compared to Chesapeake stocks. Survival and disease intensities showed statistically significant, but slight differences among stocks of Gulf origin and among stocks of Chesapeake origin. There was no significant difference in growth over the eighteen months of the experiment. The Chesapeake study also showed lower infection intensity and decreases mortality attributable to Dermo disease in Gulf stocks. There were also significant differences in disease intensity and survival among Chesapeake stocks. Additionally, the stock from Rappahannock River, VA showed increased growth compared to other stocks. In an additional study, oysters from the Chesapeake Bay study were used to determine if an association existed between disease intensity (body burden) and host defense activity, as measured by a suite of assays, including hemocyte counts, granulocyte percentage, hemocyte killing ability, serum protein concentration, and serum lysozyme activity. Development of two new assays, serum inhibition of P. marinus protease, and serum inhibition of P. marinus activity, was begun, but require additional refinement. No strong correlation or association was found, but a seasonal component was apparent in several defense assays, as well as in disease intensity. This work has identified and verified wild stocks that have been incorporated into existing breeding programs for both restoration and the development of commercial aquaculture in Chesapeake Bay and the Gulf of Mexico. The existence of disease resistant wild stocks also suggests that the conservation of wild oysters is a viable alternative or addition to current hatchery-based restoration efforts.

The purpose of the present study was to begin development of a psychological profile for environmentally ill patients. Existing psychiatric labels are unable to encompass these patients. Test scores were drawn from a pool of 89 patients whose environmental exposures were verified by the presence of toxins in the blood serum. A Mental Status Exam, a Wechsler Adult Intelligence Scale-Revised screen, and the Profile of Mood States were administered. Results indicate a primary pattern which is significantly different from test norms consisting of fatigue, reduced mental functioning, and a lack of psychotic or personality disorder indicators. The reported symptoms of environmentally ill patients were objectively verified by current psychological test instruments. The need for a new diagnostic category for people who have been poisoned by environmental toxins is discussed.

The purpose of the present study was to ascertain if environmentally sensitive patients would demonstrate different memory deficit patterns than psychiatric patients on objectively measurable memory tasks. One-hundred sixteen patients were surveyed; 56 environmentally sensitive patients were compared to 60 psychiatric patients. All subjects were administered a Wechsler Adult Intelligence Scale-Revised screen, the Wechsler Memory Scale-Revised and the Harrell-Butler Comprehensive Neurocognitive Screen after history of head injury was ruled out. Results indicate a significantly different pattern of memory dysfunction between the environmental patients and the psychiatric patients, indicating two different etiologies. A screening device derived from the coefficients from a Canonical Analysis is proposed to distinguish between the two populations in the absence of blood serum levels of environmental toxins or poisons. The detrimental effects of misdiagnosis and the beneficial effects of accurate diagnosis of environmental illness are discussed.

The diseases Dermo and MSX have devastated Chesapeake Bay populations of the eastern oyster, Crassostrea virginica. The protozoan Perkinsus marinus, which causes Dermo, is particularly problematic since it persists over a wide range of salinities and temperatures. An objective of this dissertation was to determine whether specific wild oyster stocks had developed natural resistance to Dermo and if several parameters (survival, growth, condition and energy reserves) were associated with resistance. Another objective was to characterize heat shock protein (hsp70) expression in the eastern oyster. Heat shock proteins such as hsp70 protect organisms from thermal stress and other stressors, and this function may play an important role in disease resistance in oysters. In field trials a F0 Chesapeake Bay stock from Tangier Sound (CTS) survived similarly to a disease resistant hatchery strain (XB). A Louisiana stock was also resistant to Dermo, but not MSX. Despite high mortality, a disease-susceptible stock (CRB) reached market size the fastest. Growth and condition index varied between stocks, but did not reflect Dermo resistance. Energy reserves were affected strongly by season, but not disease or stock. Results imply that Dermo resistant strains could be developed from these stocks but criteria for optimal strain selection for aquaculture and restoration may be divergent. Mortalities of F1 oysters (CRB, CTS and XB) were similar to F0 parents, demonstrating a genetic basis to Dermo resistance. Total hsp70 did not correlate with seasonal temperatures, while hsp70 isoforms (hsp69 and hsp72) varied inversely across seasons. Hsp70 did not vary significantly between strains, indicating a stronger environmental influence on hsp70 expression. In lab experiments hsp70 in oyster gills was elevated greater than two weeks after a sub-lethal heat shock. Thermal tolerance, but not hsp70, varied between CTS and Louisiana oyster stocks. Heat shock protected oysters experimentally infected with P. marinus and non-infected oysters from lethal heat stress. Infection alone induced expression of hsp70. Observed inherent and induced differences in thermal tolerance suggest that both genotype and phenotype may be manipulated to improve survival in cultured bivalves. The implications of this research for bivalve aquaculture as well as areas for future research are discussed.

Thesis (MScMedSc (Biomedical Sciences))--University of Stellenbosch, 2010.
Thesis presented in partial fulfilment of the requirements for the degree Master of Medical Science (Human Genetics) at the University of Stellenbosch.
Bibliography
ENGLISH ABSTRACT: The infectious disease tuberculosis (TB) remains the leading cause of death worldwide by a single infectious agent, despite significant advances in biomedical sciences. The idea that host genetics plays a role in the development of disease was proposed by Haldane in 1949. The observation that only 10% of immunocompetent individuals develop disease while others are able to successfully contain it, further suggests that host genetics plays an important role. TB is thus a complex disease, with the causative bacterium, Mycobacterium tuberculosis, host genetic factors and environment all contributing to the development of disease. To date several genes have been implicated in TB susceptibility, albeit with small effect. Genome-wide association studies (GWAS) offer the means to identify novel susceptibility variants and pathways through their ability to interrogate polymorphisms throughout the genome without being limited by our understanding of the immune processes involved in TB infection and disease progression. TB and sarcoidosis are both granulomatous diseases, and we therefore hypothesized that the genes and their associated variants identified in recent GWAS conducted in West Africa for TB, and Germany for sarcoidosis, could alter susceptibility to TB in the South African Coloured (SAC) population. In the sarcoidosis GWAS, ANXA11 was shown to alter susceptibility to sarcoidosis; whereas in the TB GWAS, CADM1 was found to alter susceptibility to TB. This study tested the association with TB of 16 polymorphisms in 5 potential TB host susceptibility genes in the SAC population. A well designed case-control study was employed, using the TaqMan® genotyping system to type the various polymorphisms. Any polymorphism that was found to be significantly associated with susceptibility to TB was then subjected to further analysis to determine the functional effect of the polymorphism. Promoter methylation patterns were also investigated in ANXA11 as another mechanism to elucidate its role in TB susceptibility. A 3’ UTR ANXA11 polymorphism was found to be strongly associated with susceptibility to TB, including 3 haplotypes. The gene expression analysis identified differential transcriptional levels between individual with the different genotypes, with individuals homozygous for the A-allele exhibiting a 1.2-fold increase in gene expression relative to those homozygous for the G-allele. Methylation analysis however found no differences between cases and controls. In addition, 16 novel polymorphisms were also identified, 15 of which occurred in the 3’UTR of ANXA11. The mechanism of action of ANXA11 in TB susceptibility is hypothesised to be in the area of endocytosis, autophagy or apoptosis. A weak association was noted with one of the 5’ UTR polymorphisms of CADM3, which did not hold up to further analysis in the GWAS study, and no functional work was therefore done. This work facilitates our understanding of the role of host genetics in susceptibility to TB and adds to the growing amount of information available. Proper understanding of the role that host genetics plays in TB susceptibility could result in better treatment regimens and prediction of individuals who are at a greater risk of developing TB, a disease that still kills millions of individuals annually.
AFRIKAANSE OPSOMMING: Tuberkulose is verantwoordelik vir meer sterftes as enige ander aansteeklike siekte, ten spyte van die voortuitgang wat die Biomediese Wetenskappe tans beleef. In 1949 het Haldane voorgestel dat die genetiese samestelling van die gasheer ‘n rol speel in vatbaarheid vir aansteeklike siektes. Vir tuberkulose word hierdie aanname gesteun deur die feit dat slegs 10% van individue wat geïnfekteer word aktiewe simptome ontwikkel, terwyl 90% die siekte suksesvol sal afweer. Tuberkulose is dus ‘n komplekse siekte wat veroorsaak word deur Mycobacterium tuberculosis, maar wat beïnvloed word deur genetiese sowel as omgewingsfaktore. Verskeie gene is al geïdentifiseer wat ‘n rol speel in vatbaarheid vir tuberkulose, tog is hul invloed betreklik klein. Genoom-wye assosiasiestudies (GWAS) bied unieke geleenthede vir die identifisering van nuwe polimorfismes wat genetiese vatbaarheid kan beïnvloed. Hierdie tegniek kan die hele genoom fynkam, sonder dat enige vooropgestelde idees oor die immuunrespons teen tuberkulose ‘n invloed sal hê. Tuberkulose en sarkoïdose is albei siektes wat die vorming van granulomas veroorsaak. Verskeie gene met hul geassosieerde variante is geïdentifiseer in ‘n onlangse GWAS, wat gefokus het op populasies in Wes-Afrika en Duitsland. Ons hipotese was dat die polimorfismes wat in hierdie studie geïdentifiseer is, ‘n invloed kan hê op genetiese vatbaarheid vir TB in die Suid-Afrikaanse Kleurlingbevolking (SAK). Die sarkoïdose GWAS het bevind dat ANXA11 vatbaarheid vir die siekte beïnvloed, terwyl CADM1 in die tuberkulose GWAS geïdentifiseer is. Die studie het die assosiasie tussen 16 variante en tuberkulose vatbaarheid ondersoek in die SAK populasie. Die variante strek oor 5 potensiële tuberkulose vatbaarheidsgene. Goedbeplande pasiënt-kontrole assosiasiestudies is gedoen en die polimorfismes is gegenotipeer deur gebruik te maak van die TaqMan® genotiperingsisteem. Enige polimorfisme wat beduidend met tuberkulose geassosieer was, is verder geanaliseer om die moontlike funksionele invloed daarvan te bepaal. Promotormetileringspatrone van ANXA11 is ook geanaliseer, om ‘n addisionele meganisme in tuberkulose vatbaarheidheid te ondersoek. Na genotipering van die polimorfismes is ‘n 3’ UTR ANXA11 variant geïdentifiseer wat beduidend met tuberkulose vatbaarheid geassosieer was. Drie haplotipes is ook geïdentifiseer. Geenuitdrukkingsanalise het aangedui dat verskille in transkripsie vlakke voorkom in individue met verskillende genotipes. Individue wat homosigoties was vir die A-alleel het ‘n verhoging van 1.2 in geenuitdrukking gehad, relatief tot individue wat homosigoties was vir die G-alleel. Metileringsanalise het egter geen verskil aangedui tussen pasiënte en kontroles nie. Addisioneel, is 16 nuwe variante ontdek, waarvan 15 in die 3’UTR van ANXA11 geleë was. Die meganisme waarmee ANAX11 genetiese vatbaarheid vir tuberkulose beïnvloed, blyk in die area van endositose, apoptose of outofagie, te wees. ‘n Swak assosiasie is gevind vir ‘n 5’ UTR variant van CADM3 en is nie verder opgevolg in die GWAS nie. Gevolglik is geen funksionele studies op hierdie polimorfisme gedoen nie. Hierdie studie dra by tot ons kennis oor die rol wat die genetiese samestelling van die gasheer speel in vatbaarheid vir tuberkulose. Indien die rol van mensgenetika in tuberkulose vatbaarheid korrek verstaan word, kan behandeling van die siekte verbeter word en kan individue wat ‘n hoër risiko loop om tuberkulose te ontwikkel geïdentifiseer word.

Thesis (Masters Diploma (Technology)--Cape Technikon, Cape Town,1994
Pesticides are generally used in south-Africa for the control of various pests; from insects and fungi to weeds. The agricultural industry is probably the biggest user of pesticides and therefore workers in this part of the labour force have the biggest risk of being exposed to the hazards of these essential products. During the 1988/89 deciduous fruit season the deciduous fruit industry earned approximately R1000 million in foreign exchange. It is therefore very important for this industry to produce fruit of high quality in a very competitive market. Of the total deciduous exports, apples comprised approximately 62,5%. The EIgin-Grabouw area is the biggest producer of apples. This industry is clearly very dependant on pesticides to protect its crops against pests. From time to time farm - workers are exposed to pesticides, a study was therefore performed to access the levels of exposure of farm workers. Blood and urine samples were collected in a comprehensive biological monitoring program in the Elgin area to determine, uusing clinical tests, the level of exposure to pesticides. It was decided later that the determination of pesticide residues in blood would form part of this main study. Other tests included serum and red cell cholinesterase. Samples were collected during August (start of spraying season), November (midseason) and February (end of spraying season). A multi-residue method was developed to extract organophosphate and organochlorine pesticides in whole blood. Although various methods exist, they allow only for the extraction of either organophosphates or organochlorines and not multi-residue extractions. This multi-residue method is based on the liquid/liquid extraction of a blood/Celite/ethanol mixture to extract the following pesticides: Azinphos-methyl, Chlorpyrifos, Endosulfan, Methidathion and Prothiophos. The pesticide residue levels were determined on gas chromatographs equipped with DB-5 and DB-2I0 capillary columns and flame photometric-, electron capture- and nitrogen/phosphorous detectors. The results were confirmed on a gas chromatograph with mass-selective detector in selective ion mode. Of the 402 blood samples analysed, 23 samples showed positive for organophoshates and 29 for organochlorines, and were sent for analysis on the mass spectrometer. Of those samples only one could be positively identified. The presence of the pesticide Endosulfan-B was confirmed. The confirmation of the pesticides was complicated by interfering substances that leached from the rubber stoppers of the collection vessels into the blood. Although the study showed that for practical purposes no pesticides were present, other important information was obtained about the handling and analyses of blood samples for pesticides.

Downy mildew, caused by the biotrophic Oomycete Plasmopara viticola, is one of the most important diseases of grapevines world wide. It is particularly destructive in temperate viticultural regions that experience warm wet conditions during the vegetative growth of the vine (Wong et al., 2001). The disease is not normally a problem in mediterranean climates where the growing season tends to be hot and dry (Mullins et al., 1992; Sivasithamparam, 1993). Grape downy mildew is however a major disease in Australian viticulture (McLean et al., 1984; Magarey et al., 1991). Grape downy mildew was first reported in Europe in 1878 (Viennot-Bourgin, 1981). In Australia, it was recorded for the first time in 1917 at Rutherglen in Victoria (Vic) (de Castella, 1917). The first recorded outbreak of the disease in Western Australia (WA) occurred in 1997 in a small planting of vines in the far north of the state. In the subsequent year, it was detected in widespread commercial viticulture in the Swan Valley production area, near Perth (McKirdy et al., 1999). The pathogen has since been found in all grape growing regions of WA. Since its introduction into European vineyards in the 1880?s, P. viticola has become one of the world?s most investigated grapevine pathogens. Many aspects its basic biology however remain unknown (Wong et al., 2001). Due to the recent detection of P. viticola in WA, little is known of the nature of strains of the pathogen in the state and their response to local environmental conditions. Much of the research concerning the influence of environmental factors on the development of P. viticola has been conducted in Europe e.g. parts of France and Germany. Due to significant differences in climatic conditions and a shorter selection time on the pathogen in WA, much of the information described in European studies may not be directly applicable to the grape downy mildew disease situation in WA. The focus of this thesis was to examine epidemiological aspects of P. viticola in the mediterranean climate of WA. The environmental conditions that could favour the development of epidemics by strains of the pathogen that have been detected in the state were determined. The existence of P. viticola ecotypes and genetic variation among strains from WA and the Eastern states of Australia was also investigated.

The aim of this study was to determine the serologic and molecular occurrence of Rickettsia spp., Ehrlichia spp., Babesia spp. and Hepatozoon spp. in ticks and domestic and wild animals from two conservation units in the city of Natal, Rio Grande do Norte State, Brazil. The collection period was between October 2012 and August 2013. Serum samples were tested against Rickettsia spp. antigens and Ehrlichia canis by Indirect fluorescent antibody test. Tissue samples and ticks were processed for molecular detection of the pathogens. Twenty-seven marsupials and four rodents were captured, and up to three animals of each species were euthanized. In addition, serum samples from 155 domestic animals: 53 cats living inside the units, 29 dogs domiciled around the areas and 73 dgos of the Zoonosis Control Center of the City (ZCC). Twenty dogs from ZCC were also euthanized and samples of spleen were obtained. Antibodies to at least one of the Rickettsia species tested were detected in six Didelphis albiventris and in one Rattus rattus; 17% (17/102) of the dogs presented antibodies to E. canis and 13% (20/155) of all tested domestic animals (dogs and cats) were seropositive for Rickettsia spp. antigens. Three species of ticks (Amblyomma auricularium, Ixodes loricatus and Ornithodoros mimon) were collected and one A. auricularium was positive for Rickettsia amblyommii by PCR. Two D. albiventris spleen samples amplified PCR products for Ehrlichia spp. Spleen samples from three D. albiventris and spleen and lung sample from one Necromys lasiurus were positive for Babesia spp. by PCR test. Among the 20 spleen samples from dogs subjected to molecular analysis, eight were positive by PCR for E. canis and two for H. canis
O objetivo deste estudo foi determinar a ocorrência sorológica e molecular de Rickettsia , Ehrlichia , Hepatozoon e Babesia em carrapatos e mamíferos silvestres e domésticos, provenientes de duas unidades de conservação ambiental (UC) na cidade de Natal, Rio Grande do Norte, Brasil. O período de coleta foi de outubro de 2012 a agosto de 2013. Os soros foram testados contra antígenos de Rickettsia spp. e Ehrlichia canis através da reação de imunofluorescência indireta. Amostras de tecido e carrapatos foram processadas para a detecção molecular dos patogenos. Foram capturados 27 marsupiais e quatro roedores para coleta de sangue, destes foram eutanásiados ate três animais de cada espécie e coletadas amostras de baço e pulmão. Paralelo, amostras de soro de 155 animais domésticos: 53 gatos que viviam nas UCs, 29 cães domiciliados no entorno das areas e 73 cães do Centro de Controle de Zoonoses do município, dos quais 20 tiveram amostras de baço coletadas. Foram detectados anticorpos para, pelo menos, uma das espécies de Rickettsia testadas em seis Didelphis albiventris e em um Rattus rattus , e 17 % (17/102) dos cães apresentaram anticorpos anti- E. canis e 13% (20/155) de todos os animais domésticos (cães e gatos) foram soropositivos para antígenos de Rickettsia spp. Três espécies de carrapatos (Amblyomma auricularium , Ixodes loricatus e Ornithodoros mimon ) foram coletadas e um A. auricularium foi positivo para R. amblyommii pela PCR. Duas amostras de baço de D. albiventris amplificaram produtos de PCR para Ehrlichia spp. e amostras de baço de três D. albiventris e baço e pulmão de um Necromys lasiurus foram positivas para Babesia spp. pela PCR. Entre as 20 amostras de baço de cão submetidas a análises moleculares, oito foram positivas na PCR para E. canis e duas para H. canis

Introduction – Objectives. The cardiovascular system is in direct and constant interaction with its environment. Exposure to various environmental parameters, such as low temperature, air pollution and tobacco smoke, has been strongly associated with serious or even fatal cardiovascular outcomes. Arterial stiffening and greater wave reflection are age-related vascular modifications that lead to an increased risk of cardiovascular events. The aim of this work was to explore the relationship between selected environmental factors and arterial elastic properties in an effort to elucidate the underlying mechanisms that link these factors to increased cardiovascular mortality.

Study 1: Effects of cold exposure on central and peripheral vascular tone. Our first study explored the effects of cold exposure on aortic stiffness and peripheral microvascular tone. We observed that cold exposure, in addition to its chronotropic effects, provoked an increase in aortic stiffness, as assessed by aortic pulse wave velocity, as well as significant vasoconstriction of peripheral arterioles in the microcirculation. Moreover, we explored the magnitude of this effect in a different population (Black subjects of African origin), which is traditionally characterized by exaggerated reactions to adrenergic stimuli. We noted that the vascular reactions, in terms of both aortic stiffness and microvascular vasoconstriction, were more profound in Black Africans than in age-matched Caucasian-Whites. These results argue for a direct effect of cold exposure on arterial stiffness and peripheral vascular tone, probably through activation of the orthosympathetic system.

Study 2: Exposure to ambient particulate matter and arterial stiffness. We explored the effects of acute exposure to outdoor particulate matter on aortic stiffness and aortic wave reflection. We studied the relationship between central hemodynamic parameters and ambient concentration of particulate matter in a population of patients who attended the Hypertension Clinics of Athens University. After statistical correction for a number of potential confounders, we did not observe an association between ambient concentrations of particulate matter and aortic stiffness. However, in men, particulate matter concentration was related to the amplitude of the reflected wave reaching the aorta from the periphery. These results suggest a direct acute interaction between particulate matter concentration and vascular tone, leading to an enhanced arterial wave reflection.

Study 3: The role of nicotine on the vascular effects of environmental tobacco smoke. Environmental tobacco smoke is considered as the most important source of particulate matter in the indoor environment. We recently demonstrated that exposure to tobacco smoke augmented wave reflection, an effect that was not seen after equivalent exposure to the smoke of non-tobacco, herbal cigarettes. We also noticed that the increased wave reflection was proportional to the plasma concentrations of nicotine. However, a direct causal effect between nicotine, arterial wave reflection and aortic stiffness has never been clearly demonstrated. We observed that increasing nicotine plasma concentration to levels comparable to those seen after extensive exposure to environmental tobacco smoke, provoked an increase in both aortic stiffness and arterial wave reflection after correction for heart rate and blood pressure changes. These results confirm the significant participation of nicotine in the vascular effects of passive smoking.

Conclusions. Globally, our results reveal the deleterious effects of cold, particulate matter exposure, and nicotinic stimulation on arterial stiffness, peripheral microcirculation and aortic wave reflection. The hemodynamic modifications associated with these effects may at least partially explain the causal relation between cold exposure, ambient air pollution and cardiovascular mortality.

Introduction-Objectifs. Le système cardiovasculaire est en relation directe et constante avec l’environnement. L’exposition au froid, la pollution atmosphérique et le tabagisme passif sont associés à des événements cardiovasculaires aigus graves et même fatals. La rigidification des artères et l’intensification de la réflexion de l’onde de pouls au niveau de l’aorte accompagnent le vieillissement et prédisent un risque cardiovasculaire accru. Nous avons testés l’hypothèse que les effets cardiovasculaires délétères des facteurs environnementaux comportent une altération des propriétés élastiques artérielles. Ceci pourrait être un des mécanismes physiopathologiques qui lie la mortalité cardiovasculaire aux variables environnementales.

Étude 1 :Exposition au froid ;effets centraux et périphériques. Notre première étude portait sur l’effet de l’exposition au froid sur la rigidité aortique et le tonus vasculaire des artérioles périphériques. Nous avons démontré que l’exposition au froid, hormis ses effets chronotropes, provoquait une augmentation de la rigidité artérielle – mesuré par la vitesse de l’onde de pouls au niveau de l’aorte - ainsi qu’une vasoconstriction importante au niveau des artérioles de la microcirculation. Nous avons ensuite déterminé l’amplitude de cet effet dans une autre population (sujets Africains-Noirs) qui se caractérise par des réactions plus prononcées aux différentes stimulations adrénergiques. Nous avons observé que les réactions vasculaires, tant au niveau de la rigidité aortique qu’au niveau de la microcirculation, étaient plus marquées chez les Africains-Noirs que chez les Caucasiens. Ces résultats révèlent un effet délétère de l’exposition au froid sur la rigidité aortique et le tonus vasculaire des artères périphériques, probablement via une activation du système orthosympathique.

Étude 2 :Exposition aux microparticules atmosphériques et rigidité artérielle. Nous avons ensuite investigué les effets de la pollution atmosphérique sur la rigidité artérielle et la réflexion de l’onde de pouls vers l’aorte. Nous avons étudié la relation entre les paramètres hémodynamiques centraux et la concentration atmosphérique de microparticules dans une population de patients qui ont consulté la Clinique Universitaire d’Hypertension Artérielle d’Athènes. Après correction statistique pour les facteurs confondants, nous n’avons pas observé de corrélation entre la rigidité artérielle et le taux de microparticules atmosphériques dans l’ensemble de la population investiguée. Par contre, si on restreint l’analyse aux résultats obtenus chez les sujets masculins, on s’aperçoit que la concentration atmosphérique de microparticules était associée de façon significative avec l’amplitude de l’onde réfléchie par la périphérie vers l’aorte et la pression pulsée aortique. Ces résultants suggèrent un effet direct des microparticules au niveau de la microcirculation. L’augmentation de l’amplitude de l’onde réfléchie consécutive à une vasoconstriction périphérique, modifie vraisemblablement les pressions au niveau de l’aorte chez le sujet masculin lors de pics de pollution.

Etude 3 :Le rôle de la nicotine dans les effets vasculaires du tabagisme passif. Le tabagisme passif est considéré comme la source la plus importante d’émission de microparticules au niveau domestique. Cependant, la composition chimique des particules semble jouer un rôle essentiel sur les ondes de réflexion. Nous avons démontré récemment que l’exposition passive à la fumée des cigarettes du tabac augmente l’intensité de la réflexion de l’onde de pouls. Ceci n’a pas été observé avec l’exposition à la fumée des cigarettes non tabagiques, en dépit d’une concentration ambiante tout à fait comparable de microparticules. Par ailleurs, nous avons observé que l’augmentation de l’incidence de l’onde de pouls au niveau de l’aorte était fortement associée à la concentration plasmatique de la nicotine. Un lien causal entre la nicotine, réflexion de l’onde de pouls et rigidité artérielle n’avait jamais clairement été établi. Nous avons testé cette hypothèse en administrant la nicotine pure chez des sujets sains. Nous avons observé que l’augmentation des taux plasmatiques de la nicotine à des valeurs comparables à celles qui surviennent après une exposition intensive au tabagisme passif, intensifiait la réflexion de l’onde de pouls et augmentait la rigidité artérielle. La correction statistique pour l’augmentation de la fréquence cardiaque et l’augmentation de la pression artérielle en réponse à la nicotine ne modifiait pas ces conclusions. Nos résultats démontrent ainsi les effets cardiovasculaires importants de faibles concentrations de nicotine, similaires à ceux qui sont atteints en cas d’exposition à un tabagisme passif.

Conclusions. Nos résultats révèlent les effets néfastes de l’exposition au froid et aux microparticules atmosphériques sur la rigidité artérielle, la microcirculation périphérique et la réflexion de l’onde de pouls. Nous avons pu également démontrer le rôle de la stimulation nicotinique dans les effets vasculaires aigus du tabagisme passif, comme en témoigne l’augmentation de la réflexion de l’onde de pouls au niveau aortique. Ces modifications hémodynamiques favorisent l’ischémie myocardique, et constituent un des mécanismes par lesquels l’exposition au froid et à la pollution atmosphérique favorisent la pathologie cardiovasculaire.

Doctorat en Sciences médicales
info:eu-repo/semantics/nonPublished

Five chemicals indigenous to the dental office environment that may cause toxic effects are formaldehyde, phenol, acrylic, mercury, and nitrous oxide. These chemicals create abnormal stress on physiological and psychological systems of the body resulting in symptomatology and pathology when the body defenses can no longer maintain homeostasis by adaptation. This study demonstrated serious behavioral consequences of chemical and heavy metal exposure. This study provided evidence that a significant percentage of dental office personnel who are exposed to the dental office chemicals show psycho neurological dysfunction. It was concluded that these individuals suffer adverse reactions to the chemicals in their work environment. The problem areas included perceptual motor difficulty in cognitive functioning, concern with bodily functions, despondency, and interpersonal problems.

Isolates of Monilinia fructicola (Wint.) Honey obtained from stone fruit orchards in Hawkes Bay, North Island and from Californian fruit exported to New Zealand, were tested for resistance to methyl benzimidazole carbamate (MBC). Resistant isolates from the North Island had EC₅₀ values of >30,000, and most isolates from the imported fruit had of values approximately 1.5 mg a.i./l carbendazim. Sensitive isolates failed to grow on 1 mg a.i./l carbendazim. A detached peach shoot system was used in controlled conditions for estimation of values for incubation period, latent period and rate of spore production on flowers (cv Glohaven). The same variables and the rate of colonisation of host tissue were measured on fruit (cv Fantasia) in controlled conditions. An inoculum density of 1x10⁴ spore/flower or fruit greatly increased fitness in vivo compared to an inoculum density of 1x10² spore/flower (fruit). Isolates varied considerably, but there was no consistent relationship between the degrees of resistance and fitness. This was in contrast to earlier studies with dicarboximide resistant strains of M. fructicola. The survival in the field of 10 isolates resistant or sensitive to MBC or dicarboximide fungicides on twig cankers and mummified fruit was compared. The ability to produce conidia on twig cankers inoculated in late spring 1989 was maintained by all sensitive and MBC resistant isolates for at least 1 year. The production of conidia on mummified fruit inoculated in February 1990 decreased after 2-3 months in the field but some conidia were still produced on all fruit in the following spring. Dicarboximide resistant isolates produced less conidia than either the MBC resistant and the sensitive isolates. The pathogenicity and fitness of all isolates were similar to the original values after survival for 1 year. A technique was developed to produce apothecia reliably from inoculated peach (cv Black Boy) and nectarine (cv Fantasia) fruit in controlled conditions in the laboratory. The fruit were inoculated with resistant or sensitive isolates, or combinations, and were incubated for 8 weeks at 25°C (±1°C) with 12 hours photoperiod of fluorescent light (Sylvania 2x65 W, daylight) to produce mummified fruit. The fruit were then buried in moist autoclaved peat moss for 10 weeks at 25°C (±1°C) in the dark to form stromata. These fruit were then hydrated with running tap-water (total hardness (CaCO₃) = 47 g/m³ and conductivity at 20°C = 12.7 mS/m) for 72 hours. The hydrated mummified fruit were placed in moist peat moss and were incubated for 13-14 weeks at 8°C (±0.5°C) in the dark. At the end of this period, stipe initials were visible. Differentiation of stipe initials into mature apothecia occurred within 15-20 days after transfer to 12°C (±2 °C) with a 12 hour photoperiod of fluorescent and incandescent light. All isolates produced apothecia when treated in this way. A technique for isolation of ascospore sets in linear arrangement was developed for tetrad analysis of the inheritance of resistance. At least 3 hours of fluorescent and incandescent light at 12°C (±2°C) was essential to allow ascospore ejection from individual asci taken from apothecia previously maintained in a 12 hour photoperiod at 12°C (±1°C). A water film on the surface of water agar was necessary to hold a set of ejected ascospores in linear sequence. Single ascospores were obtained in sequence with the aid of a micromanipulator. Genetic analysis of MBC resistant isolates was carried out on ascospores derived from apothecia produced in the laboratory. Analysis of ascospore sets in linear arrangement and ascospore populations indicated that resistance to >30,000 mg a.i./l carbendazim (high-resistant) is governed by a single major gene and is affected by gene conversion mechanisms. Crossing over was frequent, suggesting that recombination of resistance with other characters, such as pathogenicity and fitness, may occur readily. The segregation ratio (1:1) from most resistant isolates revealed that heterokaryons containing both resistant and sensitive alleles were common in resistant populations and that resistance is dominant. Allozyme analysis of ascospore progeny through electrophoresis revealed a narrow genetic base of M. fructicola in New Zealand. The technique for reliable apothecial production in controlled conditions developed in this study provided an important step for the determination of the biology of M. fructicola strains resistant to MBC fungicides, and the complexity of its life cycle. Genetic heterogeneity in field populations can be conserved in one isolate through heterokaryosis, thus providing for adaptability of the pathogen to the changing environmental conditions. Knowledge on genetic variability, overwintering ability, pathogenicity and fitness factors may be useful for future management strategies of stone fruit brown rot. Special emphasis should be made in particular to prevent primary infection on blossoms, which would delay the establishment of recombinant strains of M. fructicola and the onset of brown rot epidemics.

Thesis (MSCMedSc)--Stellenbosch University, 2012.
Includes bibliography
ENGLISH ABSTRACT: Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease in the world. The disease spectrum of NAFLD extends from steatosis (types 1,2) to non-alcoholic steatohepatitis (NASH) with inflammation (types 3,4). The aims of the study were 1) to analytically validate high-throughput real time polymerase chain reaction (RT-PCR) assays for three selected single nucleotide polymorphisms (SNPs), FTO rs9939609 (intron 1 T>A), TNF-α rs1800629 (-308 G>A) and PPARγ rs1801282 (Pro12Ala, 34 C>G), and 2) to perform genotype-phenotype association studies in relation to biochemical abnormalities, disease severity and age of onset. A total of 119 patients with fatty liver identified on ultrasound, including 88 histologically confirmed NAFLD patients, and 166 control individuals were genotyped for the three selected SNPs. RT-PCR validated against direct sequencing as the gold standard was used for detection of genetic variation. All three SNPs were in Hardy Weinberg equilibrium in the study population, except for a deviation in genotype distribution detected for PPARγ rs1801282 in the NAFLD patient subgroup (p<0.001). After adjustment for age and gender, the risk-associated FTO rs9939609 A-allele was detected at a significantly higher frequency in the Caucasian compared with Coloured patients (p=0.005). The opposite was detected for the risk-associated TNF-α rs1800629 A-allele, which occurred at a significantly higher frequency in the Coloured compared with Caucasian NAFLD patients (p=0.034). The onset of fatty liver disease symptoms was on average 5 years younger in the presence of each risk-associated TNF-α rs1800629 A-allele (p=0.028). When considered in the context of an inferred genotype risk score ranging from 0-6, disease onset occurred on average 3 years earlier (p=0.008) in the presence of each risk-associated FTO A-allele, TNF-α A-allele or PPARγ C-allele. After adjustment for age, gender and race, no differences in genotype distribution or allele frequencies were observed between histologically confirmed NAFLD (types 1,2) and NASH (types 3,4) patients, while the minor allele frequency for the TNF-α rs1800629 was significantly higher in the total NAFLD (types 1-4) (p=0.047) as well as NASH subgroup (NAFLD types 3,4) (p=0.030) compared with obese patients without a histologically confirmed NAFLD diagnosis. A significant correlation was furthermore observed between the number of TNF-α rs1800629 A-alleles and increasing CRP levels (p=0.029), with a favourable reduced effect in the presence of low- to moderate alcohol intake. The average waist circumference of physically active NAFLD patients was 12% lower than in physically inactive patients (p=0.004). In view of the results presented in this study, the inclusion of the selected SNPs, and in particular the pro-inflammatory TNF-α rs1800629 polymorphism, may be considered as part of a comprehensive cardiovascular risk evaluation of NAFLD patients. Ultimately, early detection of patients with fatty liver disease symptoms and effective intervention based on the underlying disease mechanism may prevent progression from NAFLD to NASH, shown to be an independent risk factor for cardiovascular diseases.
AFRIKAANSE OPSOMMING: Nie-alkoholiese lewervervetting (NALV) is die mees algemene kroniese lewersiekte in die wêreld. Die siektespektrum van NALV strek van steatose (vervette lewer tipes 1,2) tot steatohepatitis met inflammasie (NASH tipes 3,4). Die doel van die studie was 1) om analities die hoë omset polimerase kettingreaksie (RT-PKR) metode te valideer vir die geselekteerde enkel nukleotied polimorfismes (ENPs) FTO rs9939609 (intron 1 T>A), TNF-α rs1800629 (-308 G>A) en PPARγ rs1801282 (Pro12Ala, 34 C>G), en 2) om genotipe-fenotipe assosiasie studies uit te voer ten opsigte van relevante biochemiese abnormaliteite, graad van die siekte en aanvangsouderdom. ’n Totaal van 119 pasiënte met vervette lewers is geïdentifiseer met behulp van ultraklank, insluited 88 histologies-bevestigde NALV pasiënte, en 166 kontrole individue. Hierdie pasiënte is gegenotipeer vir die 3 geselekteerde ENP’s. RT-PKR gevalideer met direkte DNA volgorde bepaling as die goue standaard, is gebruik vir opsporing van genetiese variasie. Al die ENP’s was in Hardy Weinberg ekwilibrium in die studie populasie, behalwe vir ’n afwyking in genotipe verspreiding waargeneem vir PPARγ in die NALV subgroep (p<0.001). Nadat aanpassings gemaak is vir ouderdom en geslag, is die risiko-geassosieerde FTO rs9939609 A-alleel waargeneem teen ’n betekenisvol hoër frekwensie in die Kaukasiese pasiënte in vergelyking met Kleurling pasiënte (p=0.005). Die teenoorgestelde is waargeneem vir die risiko-geassosieerde TNF-α rs1800629 A-alleel wat voorgekom het teen ’n betekenisvol hoër frekwensie in die Kleurling NALV pasiënte, in vergelyking met Kaukasiese NALV pasiënte (p=0.034). Die aanvang van NALV was gemiddeld 5 jaar vroeër in die teenwoordigheid van elke risiko-geassosieerde TNF-α rs1800629 A-alleel (p=0.028). Met inagneming van ’n genotipe risiko telling tussen 0–6, het aanvang van siekte gemiddeld 3 jaar vroeër voorgekom (p=0.008) in die teenwoordigheid van elke toenemende risiko-geassosieerde FTO A-alleel, TNF-α A-alleel en PPARγ C-alleel. Nadat aanpassings gemaak is vir ouderdom, geslag en ras, is geen verskille waargeneem in genotipe verspreiding of alleel frekwensies tussen histologies bevestigde NALV (tipes 1,2) en NASH (tipes 3,4) pasiënte nie, terwyl die minor alleel telling vir die TNF-α rs1800629 betekenisvol hoër was in die totale NALV (tipes 1–4) (p=0.047) asook die NASH subgroep (NALV tipes 3,4) (p=0.03) in vergelyking met vetsugtige pasiënte sonder ’n histologies bevestigde diagnose. ‘n Statisties beteknisvolle korrelasie is verder waargeneem tussen die aantal TNF-α rs1800629 A-allele en toenemende CRP vlakke (p=0.029), met n gunstige verlaagde effek in die teenwoordigheid van lae alcohol gebruik. Die gemiddelde middellyf-omtrek van fisies aktiewe NALV pasiënte was 12% minder as fisies onaktiewe pasiente (p=0.004). Na aanleiding van die resultate van hierdie studie behoort insluiting van geselekteerde ENP’s, en in besonder die pro-inflammatoriese TNF-α rs1800629 polimorfisme, as deel van ’n omvattende kardiovaskulere risiko evaluasie oorweeg te word. Aan die einde van die dag mag vroeë identifikasie van NALV pasiente en effektieve intervensie gebasseer op die onderliggende siekte meganisme, vordering tot NASH verhoed wat getoon is om ’n onafhanklike risiko faktor vir kardiovaskulêre siekte te wees.
Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Pathology

In the KwaZulu-Natal (KZN) Midlands North region of South Africa, the importance and increased prevalence of endemic scarabaeids, particularly Hypopholis sommeri Burmeister and Schizonycha affinis Boheman (Coleoptera: Melolonthinae), as soil pests of sugarcane, and a need for their control was established. The development of a mycoinsecticide offers an environmentally friendly alternative to chemical insecticides. The identification of a diversity of white grub species, in two Scarabaeidae subfamilies, representing seven genera were collected in sugarcane as a pest complex. Hypopholis sommeri and S. affinis were the most prevalent species. The increased seasonal abundances, diversity and highly aggregated nature of these scarabaeid species in summer months, suggested that targeting and control strategies for these pests should be considered in this season. Increased rainfall, relative humidity and soil temperatures were linked to the increased occurrence of scarab adults and neonate grubs. Beauveria brongniartii (Saccardo) Petch epizootics were recorded at two sites in the KZN Midlands North on H. sommeri. Seventeen different fluorescently-labelled microsatellite PCR primers were used to target 78 isolates of Beauveria sp. DNA. Microsatellite data resolved two distinct clusters of Beauveria isolates which represented the Beauveria bassiana senso stricto (Balsamo) Vuillemin and B. brongniartii species groups. These groupings were supported by two gene regions, the nuclear ribosomal Internal Transcribed Spacer (ITS) and the nuclear B locus (Bloc) gene of which 23 exemplar Beauveria isolates were represented and sequenced. When microsatellite data were analysed, 26 haplotypes among 58 isolates of B. brongniartii were distinguished. Relatively low levels of genetic diversity were detected in B. brongniartii and isolates were shown to be closely related. There was no genetic differentiation between the two sites, Harden Heights and Canema in the KZN Midlands North. High gene flow from swarming H. sommeri beetles is the proposed mechanism for this lack of genetic differentiation between populations. Microsatellite analyses also showed that B. brongniartii conidia were being cycled from arboreal to subterranean habitats in the environment by H. sommeri beetles. This was the first record of this species of fungus causing epizootics on the larvae and adults of H. sommeri in South Africa. The virulence of 21 isolates of Beauveria brongniartii and two isolates of B. bassiana were evaluated against the adults and larvae of S. affinis and the adults of H. sommeri and Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae). Despite being closely-related, B. brongniartii isolates varied significantly in their virulence towards different hosts and highlighted the host specific nature of B. brongniartii towards S. affinis when compared to B. bassiana. Adults of S. affinis were significantly more susceptible to B. brongniartii isolates than the second (L2) or third instar (L3) grubs. The median lethal time (LT₅₀) of the most virulent B. brongniartii isolate (C13) against S. affinis adults was 7.8 days and probit analysis estimated a median lethal concentration (LC₅₀) of 4.4×10⁷ conidia/ml⁻¹. When L2 grubs were treated with a concentration of 1.0×10⁸ conidia/ml⁻¹, B. brongniartii isolates HHWG1, HHB39A and C17 caused mortality in L2 grubs within 18.4-19.8 days (LT₅₀). Beauveria brongniartii isolate HHWG1 was tested against the L3 grubs of S. affinis at four different concentrations. At the lowest concentration (1×10⁶ conidia/ml⁻¹), the LT₅₀ was 25.8 days, and at the highest concentration (1×10⁹ conidia/ml⁻¹) the LT₅₀ dropped to 15.1 days. The persistence of B. bassiana isolate 4222 formulated on rice and wheat bran and buried at eight field sites in the KZN Midlands North was evaluated by plating out a suspension of treated soil onto a selective medium. All eight field sites showed a significant decline in B. bassiana CFUs per gram of soil over time, with few conidia still present in the samples after a year. Greater declines in CFUs were observed at some sites but there were no significant differences observed in the persistence of conidia formulated on rice or wheat bran as carriers. Overall, poor persistence of B. bassiana isolate 4222 was attributed to suboptimum temperatures, rainfall, which rapidly degraded the nutritive carriers, attenuated fungal genotype and the action of antagonistic soil microbes. Growers’ perceptions of white grubs as pests and the feasibility of a mycoinsecticide market were evaluated by means of a semi-structured questionnaire. The study showed that the reduced feasibility of application, general lack of potential demand for a product, high cost factors and most importantly, the lack of pest perception, were factors which would negatively affect the adoption of a granular mycoinsecticide. Growers however exhibited a positive attitude towards mycoinsecticides, and showed all the relevant attributes for successful technology adoption. It is recommended that because B. brongniartii epizootics were recorded on target pests which indicated good host specificity, dispersal ability and persistence of the fungus in the intended environment of application; that a mycoinsecticide based on this fungal species be developed. What will likely increase adoption and success of a mycoinsecticide is collaboration between various industries partners to increases market potential in other crops such as Acacia mearnsii De Wild (Fabales: Fabaceae).

The broad objective of the study was to determine the economic value of local pigs in marketand subsistence-oriented production systems in communal areas of Southern Africa. Data were collected from 288 households to investigate farmer perceptions, effects on pig production and handling of disease outbreaks such as classical swine fever (CSF) in market- and subsistenceoriented production systems. The utilisation of local pigs in these market- and subsistenceoriented production systems in improving people‟s welfare was evaluated. Climate change was identified by farmers in these production systems as a major constraint to pig production hence an experiment was carried out in the hottest season to determine diurnal heat-related physiological and behavioural responses in Large White (LW) and South African local pigs. The same genotypes were used to determine effects of diurnal heat-related stress on their growth performance. Choice experiment was done to determine farmer preferences for local pig traits and implicit prices for these traits in CSF-affected and unaffected areas that were under subsistence- and market-oriented production systems. In this experiment, the importance of heat tolerance was assessed relative to other productive and climate change adaptation traits. Significantly more pigs were culled in the CSF-affected areas that were market-oriented (8.0 ± 1.76) than subsistence-oriented (4.1 ± 1.00) production system. The risk of parasites and disease challenges was high in subsistence-oriented production system and coastal areas. In both production systems, CSF was perceived as destructive since the culling of pigs affected pork availability and income generation. The high risk of disease outbreaks and threat of climate change caused farmers in subsistence-oriented production system to select local pigs for their adaptive traits while those in the market-oriented production system focused on productive imported pigs. Farmers (83 %) indicated that they wanted pig genotypes that were adapted to climate change effects such as hot conditions. Local pigs were found to have superior heat tolerance over LW pigs (P < 0.05) in terms of lower heart rate and skin surface temperature. Frequency per day and duration for behavioural heat loss activities such as wallowing, sleeping in a prostrate posture and sprawling in slurry were also lower (P < 0.05) for local than LW pigs. The superiority of heat tolerance of local over LW pigs was further confirmed by their uncompromised growth performance under high diurnal temperatures. The Pearson‟s product moment correlation coefficient between temperature and feed conversion ratio for LW pigs was strongly positive (r = 0.50; P < 0.001) unlike the weak and positive correlation for local pigs (r = 0.20; P < 0.05). There was a quadratic relationship between temperature and average daily gain (ADG) for both pig genotypes. The regression coefficients for ADG were higher (P < 0.001) for LW than local pigs. It was concluded that at high ambient temperatures, performance of local pigs was less compromised than for LW pigs. Although local pigs were found to be heat tolerant, results of choice experiment showed that this trait was not selected for relative to other traits. Keeping pigs that required bought-in feeds, fell sick often and produced low pork quality (eating quality based on farmer perceptions) negatively affected farmers‟ livelihoods more in subsistence- than market-oriented production system. Farmers in market-oriented production system derived more benefit from productive traits such as heavier slaughter weights and large litter size than subsistence-oriented farmers. Under the subsistence-oriented production system, farmers in CSF-affected areas placed high prices on adaptive traits than the unaffected areas. Subsistence-oriented farmers who were affected by CSF wanted a total compensation price of R10 944.00 (USD1563.43) for keeping a pig genotype with unfavourable traits when compared to R4235.00 (USD605.00) for their CSF-unaffected counterparts. Implicit prices for traits could not be determined for market-oriented production system. It was concluded that farmers in CSFaffected areas placed high economic values on pig traits than farmers from the CSF-unaffected areas. The findings suggest that adapted local pigs can be promoted in subsistence-oriented production systems while productive imported pigs and their crosses with local pigs can be kept in market-oriented production systems.

Thesis (MSc)--University of Stellenbosch, 2005.
ENGLISH ABSTRACT: Water quality analysis forms the basis in assessing and monitoring catchments. As urban development continuously increase, pollution sources increase in either point source (wastewater treatment works, industrial effluents) and/or non-point source origin (storm water discharge, domestic pollutants), accumulating pollutants in the environment. It was only recently discovered that certain pollutants have subtle disrupting effects on the endocrine system resulting in health related problems associated with the reproductive system and thyroid system (growth and development) of animals and potentially humans. Natural water resource management proves to include limited biological assays measuring endpoints for cytoxicity, inflammatory activity and endocrine disruption. The broad objective of this study was therefore to include several bioassays, not normally used in municipal (City of Cape Town) monitoring programmes, along with water quality data collected by the City of Cape Town. The Eerste/Kuils River catchment system, Western Cape, under the auspices of the City of Cape Town was chosen, and although this catchment does not contribute to drinking water resources, is subjected to a range of anthropogenic influences (industrial effluents, household wastewater, agricultural runoff). Within the short time-frame available for this study (six months) two months, July (following a dry summer and autumn season) and October (following a wet winter and early spring season) were selected for water quality monitoring. Spatial variation (with relevance to specific point and non-point contamination) among sampling sites were also obtained by choosing several (n=10) along the catchment. Specific aim of the study therefore included: Firstly (Chapter 2), the use of in vitro bioassays, lactate-dehydrolises assay (LDH) for cytotoxic activity, pro-inflammatory hormone Interleukin-6 (IL-6) secretion by human blood cells and a specific Salmonella ELISA for faecal contamination, in conjunction with routine chemical and biological (mostly microbiological) monitoring activities. The study indicated significant variation among sites in all microbiological measures as well in IL-6 secretion and Salmonella presence. Between months, variations were also evident in certain variables. Secondly (Chapter 3), two bioassays using the yolk precursor protein, vitellogenin (Vtg) as endpoint was implemented in a) an in vitro Xenopus laevis liver slice assay (five day exposure) and b) an in vivo Zebrafish (Danio rerio) bioassay (seven day exposure) assessing estrogenic activity in the Eerste/Kuils River catchment. Although estrogen spiked positive control water samples stimulated Vtg production in vitro as well as in vivo, no dramatic estrogenic activity was measured at any of the selected sites. Thirdly (Chapter 4), a bioassay using the thyroid controlled metamorphosis in Xenopus laevis tadpoles to assess effects on the thyroid hormonal system was implemented. Thyroid stimulatory activity, compared with a negative control sample, was measured at two sites along the catchment. Although the practical implementation of the tadpole semi-static exposure protocol (water replacement) proved to be labour intensive, all the added bioassays proved to be valuable tools to add valuable information regarding water quality. It is clear that more research related to anthropogenic influences along the Eerste/Kuils River catchment system are needed, specifically in monitoring monthly variations to better understand annual variation in several of the endpoints studied.
AFRIKAANSE OPSOMMING: Waterkwaliteit vorm die basis vir die evaluering en monitering van opvangsgebiede. Voortdurende stedelike ontwikkeling gee aanleiding tot ‘n toename in die voorkoms van besoedelstowwe in die natuurlike omgewing deur gelokaliseerde (punt) bronne (rioolwerke/industriële uitvloeisel) en/of nie gelokaliseerde (nie punt) bronne (vloed uitlaat/huishoudelike uitvloeisels) van besoedeling. Dit het onlangs aan die lig gekom dat van hierdie chemise besoedelstowwe subtiel die endokriene sisteem versteur en so aanleiding gee tot gesondheidsprobleme in terme van die voortplantingsisteem en tiroied sisteem (groei en ontwikkeling) by diere en moontlik ook die mens. Daar is beperkte gebruik van biologiese toetse wat inligting verskaf oor sitotoksiteit, inflammatoriese aktiwiteit en endokriene versteuring. Die doel van hierdie studie was dus om van hierdie biologiese toetse, wat normaalweg nie deel uitmaak van die roetine munisipale (Stad van Kaapstad) opvangsgebied monitering nie, gebruik te maak. Die Eerste-, Kuilsrivier, Wes Kaap, onder beheer van Stad Kaapstad is gekies en alhoewel die opvangsgebied nie water bydra tot drinkwaterbronne nie, word die opvangsgebied beïnvloed deur verskeie mensgemaakte bronne van besoedeling (afloop vanuit omliggende lanbougebiede). Binne die kort tydsraamwerk van die projek (ses maande) is besluit om twee maande, Julie (volg ‘n droë somer en herfs seisoen) en Oktober (volg ‘n nat winter en vroeë lente seisoen) vir water kwaliteit monitering te kies. Ruimtelike variasie langs die loop van die opvangsgebied is ingesluit deur moniteringspunte (n=10), met in ag name van die potensiële besoedelingsbronne. Spesifieke doelwitte van die projek sluit in: Eerstens (Hoofstuk 2), om die in vitro biotoetse, laktaat hidrolise (LDH) vir sitotoksisiteit, proinflammatoriese hormoon Interleuikin-6 (IL-6) vir inflammatoriese aktiwiteit, vrygestel deur menslike bloedselle en ‘n Salmonella ELISA vir ontlasting besoedeling saam met bestaande chemise en biologiese (hoofsaaklik migrobiologiese) veranderlikes te gebruik. Die studie het getoon dat beduidende variasie in alle mikrobiologiese toetse asook IL-6 vrystelling en Salmonella voorkoms bestaan het tussen versamelpunte. Maandelikse variasie in sekere van die veranderlikes het ook voorgekom. Tweedens (Hoofstuk 3), is twee biotoetse wat die dooiervoorloperproteïen, vitellogeen (Vtg) as eindpunt gebruik geimplimenteer in a) ‘n in vitro Xenopus laevis lewersnit biotoets (vyf dag blootstelling) en b) ‘n in vivo Zebravis (Danio rerio) biotoets (sewe dag blootstelling) om estrogenisiteit in die Eerste-, Kuilsrivier opvangsgebied te evalueer. Alhoewel, die estrogeen behandelde positiewe kontrole water monsters Vtg produksie veroorsaak het in beide die in vitro lewer-kulture en in vivo vistoets, is geen dramatiess estrogeniese aktiwiteit by enige van die moniteringspunte gevind nie. Derdens (Hoofstuk 4), is ‘n biotoets wat die tiroïedbeheerde metamorfose in Xenopus laevis paddavisse gebruik om effekte op die tiroïedsisteem te evalueer. Die differensiële stimulering (versnelling), in vergelyking met ‘n negatiewe kontrole watermonster, van die tiroied sisteem is by twee moniteringspunte in die opvangsgebied waargeneem. Alhoewel die praktiese implementering van die paddavis semi-statiese (water word gereeld vervang) biotoets arbeidsintensief is, het alle bykomstige biotoetse waardevolle bykomstige inligting oor water kwaliteit verskaf wat ‘n belangrike bydrae tot ingeligte bestuursbesluite kan verleen. Dit is duidelik dat meer navorsing int verband met die menslike invloed langs die Eerste-, Kuilsrivier opvangsgebied nodig is, veral met maandlikse monitering vir seisoenale veranderinge.

[Truncated abstract] Industrial processing to refine alumina from bauxite ore produces millions of tonnes of refining residue each year in Australia. Revegetation of bauxite residue sand (BRS) is problematic for a number of reasons. Harsh chemical conditions caused by residual NaOH from ore digestion mean plants must overcome extremely high pH (initially >12), saline and sodic conditions. At such high pH, manganese (Mn) is rapidly oxidised from Mn2+ to Mn4+. Plants can take up only Mn2+. Thus, Mn deficiency is common in plants used for direct BRS revegetation, and broadcast Mn fertilisers have low residual value. Added to this, physical conditions of low water-holding capacity and a highly compactable structure make BRS unfavourable for productive plant growth without constant and large inputs of water as well as Mn. However, environmental regulations stipulate that the residue disposal area at Pinjarra, Western Australia, be revegetated to conform with surrounding land uses. The major land use of the area is pasture for grazing stock. Hence, pasture revegetation with minimum requirement for fertiliser and water application is desirable. This thesis investigates a number of avenues with potential for maintaining a productive pasture system on BRS whilst reducing the current level of Mn fertiliser and irrigation input. Emphasis was placed on elucidation of chemical and physical factors affecting Mn availability to plants in BRS

Volatile loss rates of pesticides from turfgrass were measured using the Backward-Time Lagrangian Stochastic Dispersion model (Flesch et al., 1995). Solar radiation, ambient temperature, surface temperature, relative humidity, wind direction, and wind speed were monitored continuously. Growth regulator was applied to the turf plot several days before pesticide application to maintain a constant grass height and aerodynamic roughness length during the experiment. No irrigation occurred following application. Pesticides were applied as mixtures to allow direct comparison of evaporative loss. Mixtures studied were chlorpyrifos + triadimefon + ethofumesate and triclopyr (acetic acid) + propiconazole + cyfluthurin. Airborne flux estimates correlated with temperature, solar radiation, wind speed, time, and vapor pressure of the active ingredient. A log vapor pressure vs. 1/Temperature (K) relationship was observed between flux and surface temperature over a single day for most pesticides. An exponential attenuation of flux was observed over a period of several days and correlated with attenuation of dislodgeable surface residues for two of the pesticides. A fugacity-based model for predicting initial evaporative loss rates from turf grass is presented. Input parameters include pesticide vapor pressure, molecular diffusion coefficient, surface temperature, wind speed profile, atmospheric stability, surface roughness, and average upwind fetch. The GC retention method (Jensen, 1966) was used to estimate pesticide vapor pressures over an environmentally relevant temperature range. The model predicts fluxes that are an order of magnitude greater than measured values. This bias may be due, in part, to deviation from the assumption of pesticide saturated vapor density at the foliar surface. In addition, sensitivity analysis suggests improved estimates of leaf surface temperature and pesticide vapor pressures have the greatest potential to improve model performance.
Graduation date: 2003

Thesis (M.Tech.: Environmental Health)-Durban Institute of Technology, 2005 1 v. : ill. ; 30 cm
South Durban is in the province of Kwazulu-Natal in South Africa and is home to two international petro-chemical refineries, a paper mill, sewage works, an international airport, a chemical tank farm with approximately 970 tanks, a number of landfill sites, an airport, various processing and manufacturing industries which are all in close proximity to residential and recreational areas. This area is known as the South Durban Industrial Basin (SDIB). Serious concerns have arisen about the potential health impacts that could arise from ambient air pollution from these industries. Learners and staff at the Settlers Primary School situated in Merebank, a suburb in the SDIB, perceived themselves to be at risk for air pollutant related health effects owing to the schools’ geographic location. The aims of this study was a) to determine the prevalence of asthma among learners from Grades 3 and 6 and staff at Settlers Primary School and b) To investigate whether outdoor air pollutant concentrations of sulphur dioxide (SO2), oxides of nitrogen (NOx), ozone (O3), total reduced sulphur (TRS), carbon monoxide (CO) and respirable particulate matter less than 10 microns (PM10) were associated with increased signs and symptoms of asthma in the study population.

The risk of autoimmune disorders such as multiple sclerosis (MS) may be influenced by environmental factors early in life. This epidemiological thesis provides new knowledge on the role of early life environmental factors in MS in particular, for which the specific aetiology is unknown. Two main potential environmental determinants of MS, ultraviolet radiation (UVR) and infections, are explored through an analysis of their timing of action in the life course and a consideration of their possible protective effects. Other organ-specific autoimmune disorders whose aetiology is also unknown, including type 1 diabetes and rheumatoid arthritis (RA), are also assessed for links with UVR for comparison with MS. Two existing national Australian datasets provided the outcome data for the analyses. The 1995 Australian National Health Survey (NHS) provided summary prevalence estimates for ecological (population-level) analysis of four immune disorders other than MS. The 1981 Australian MS Survey, used for the largest part of the thesis, provided individual-level MS-case data for 1981 throughout Australia, and was further modified to construct a longitudinal MS-rates study dataset for analysis of timing of birth. Ecological analysis of the 1995 NHS data showed that geographic latitude was positively associated, and regional ambient UVR inversely associated, with the prevalence of type 1 diabetes in Australia. Ambient UVR exposure may thus be a protective factor against such disease at the population level. The association supports previous ecological findings for MS in Australia and adds to the evidence that UVR exposure might be a modifiable determinant for autoimmune disease generally. Longitudinal analysis of the reconstructed 1981 Australian MS Survey dataset showed that increased MS risk of around 30% was evident in Australians born in November to December (southern hemisphere early summer) compared with those born in May to June (early winter). This MS-risk pattern, indicating environmental factor(s) acting around the time of birth, mirrored (seasonally) that seen for MS in the northern hemisphere, suggesting globally similar perinatal environmental determinants modifying the risk of MS onset. Most importantly, this Australian pattern was found to be fully accounted for by individual, regional (state) and seasonal ambient UVR levels specific to the prenatal period seven to eight months before birth. Low ambient (maternal) UVR exposure in the first trimester of pregnancy thus appears to be associated with a higher risk of MS in the offspring. Birth-order analysis of cases in the 1981 MS Survey further showed that early birth order was independently associated with MS risk, MS cases being more likely to be one of the older siblings in their sibships. Consistent with the hygiene hypothesis, this result suggests that a lack of microbial exposure in early childhood may increase MS risk later in life. Population health implications of these findings are discussed. In particular, safe sun exposure and/or vitamin D supplementation during early pregnancy may help prevent subsequent onset of high-morbidity, long-duration and presently incurable autoimmune disorders such as MS in the offspring.

Background Climate variation has affected diverse physical and biological systems worldwide. Population health is one of the most important impacts of climate variation. Although the impact of climate variation on infectious diseases has been of significant concern recently, the relationship between climate variation and infectious diseases, including vector-borne diseases and enteric infections, needs greater clarification. Australia is grappling with developing politically acceptable responses to global warming. In China, few studies have been conducted to examine the effect of climate variation, including global warming, on population health. As residents of developing countries may suffer more from climate change compared with people living in more developed countries, this thesis has significance for both countries. Aims This study aims to contribute to a better understanding of the impact of climate variation on population health, and to provide scientific evidence for policy makers, researchers, public health practitioners and local communities in the development of public health strategies at an early stage, in order to prevent or reduce future risks associated with ongoing climate change. The objectives of this study include: (1) to quantify the association between climate variation and selected vectorborne diseases and enteric infections in different climatic regions in Australia and China; (2) to project the future burden of selected vector-borne diseases and enteric infections based on climate change scenarios in different climatic regions in Australia and China. Methods This ecological study has two components. The first uses time-series analyses to quantify the relationship between meteorological variables and infectious diseases, whereas the second projects the burden of selected infectious diseases using future climate and population scenarios. Temperate and subtropical climatic zones in both Australia and China were selected as the primary study areas, and a study of an Australian tropical region was also conducted. Study of Australia’s temperate zones was conducted in Adelaide, South Australia, as well as the Murray River region in that State. The study of China’s temperate zone was carried out in Jinan, Shandong Province. Subtropical studies were conducted in Baoan, Guangdong Province, China, and Brisbane in Queensland, whilst research for the tropics centred on Townsville, also in Queensland, Australia. The selected infectious diseases - one vector-borne disease and one enteric infection in each country - are Ross River Virus (RRV) infection and salmonellosis in Australia, and malaria and bacillary dysentery in China. Study periods vary from eight to sixteen years (depending upon the availability of data). Climate data, infectious disease surveillance data and demographic data were collected from local authorities. Data analyses conducted in the ecological studies include Spearman correlation analysis, time-series adjusted Poisson regression and the Seasonal Autoregressive Integrated Moving Average (SARIMA) model with consideration of lag effects, seasonality, long-term trends, and autocorrelation, on a weekly or monthly basis depending on data availability, and Hockey Sticky model to detect potential threshold temperatures. In the burden of disease component, analyses include the calculation of an indicator of the burden of disease - Years Lost due to Disabilities (YLDs) - and use scenario-based models to project YLDs for the selected diseases in 2030 and 2050 in Australia and 2020 and 2050 in China respectively. The projections consider both different scenarios of projected temperature and future population change. Results Relationship between climate variation and selected infectious diseases In all the study regions in Australia, maximum temperature, minimum temperature, rainfall and humidity are all significantly related to the number of RRV infections, with lag effects varying from 0 to 3 months. Additionally, high tides in the two seaside regions with tropical (Townsville) or subtropical (Brisbane) climates, and river flow in the temperate region (Murray River region), are related to the number of cases without any lag effects. A potential 1°C increase in maximum or minimum temperature may cause 4%~23% extra cases of RRV infection in the temperate region, 5~8% in the subtropical region, and 6%~15% in the tropical region. Maximum temperature, minimum temperature, humidity and air pressure are significantly related to malaria cases in the temperate city Jinan and subtropical city Baoan in China, with a lag effect range of 0 to 1 month. An association between rainfall and malaria cases was not detected in either region. A potential 1°C increase in maximum or minimum temperature may lead to 4%~15% extra malaria cases in the temperate region, and 12%-18% in the tropical region in China. Maximum temperature, minimum temperature, rainfall and humidity are all significantly related to the number of salmonellosis cases in the three study cities in Australia, with lag effects varying from 0 to 1 month. A potential 1°C increase in maximum or minimum temperature may cause 6%~19% extra salmonellosis cases in the temperate region (Adelaide), 5%~10% in the subtropical region (Brisbane), and 4%~15% in the tropical region (Townsville). The thresholds for the effects of maximum and minimum temperatures are 20ºC and 12ºC respectively in Adelaide. No threshold temperatures are detected in Townsville and Brisbane. Maximum temperature, minimum temperature, humidity, air pressure and rainfall are significantly related to bacillary dysentery cases in the temperate city Jinan and subtropical city Baoan in China, with the lag effect range of 0 to 2 months. A potential 1°C increase in maximum or minimum temperature may cause 7%~15% extra bacillary dysentery cases in the temperate region and 10% ~ 19% in the subtropical region in China. The thresholds for the effects of maximum and minimum temperatures on bacillary dysentery are 17ºC and 8ºC respectively in Jinan. No threshold temperatures are detected in Baoan. Projection of YLDs from target diseases In Australia, considering both climatic and population scenarios, if other factors remain constant, compared with the YLDs observed in 2000, the YLDs for salmonellosis might increase by up to 48% by 2030, and nearly double by 2050 in South Australia, while the YLDs might double by 2030 and increase by up to 143% by 2050 in Brisbane, Queensland. The YLDs for RRV infection might increase by up to 66% by 2030, and nearly double by 2050 in South Australia. They might increase by up to 61% by 2030 and double by 2050 in Brisbane, Queensland. In China, considering both climatic and population scenarios, if other factors remain constant, compared with the YLDs observed in 2000, the YLDs for bacillary dysentery might double by 2020 and triple by 2050 in both Jinan and Baoan. The YLDs for malaria might increase by up to 108% by 2020 and nearly triple by 2050 in Jinan, the temperate city, and increase by up to 144% by 2020 and nearly triple by 2050 in Baoan, the subtropical city. Conclusions 1. Both maximum and minimum temperatures are important in the transmission of vector-borne diseases in various climatic regions in both Australia and China. River flow or high tides may also play an important role in the transmission of such diseases. 2. Both maximum and minimum temperatures play an important role in the transmission of enteric infections in various climatic regions in both Australia and China, with a threshold temperature detected in the temperate regions but not in subtropical and tropical regions. 3. The effects of rainfall and relative humidity on selected infectious diseases vary in different study areas in Australia and China. 4. The burden of temperature-related infectious diseases may greatly increase in the future if there is no effective preventive intervention. Public health implications 1. Implication for health practice • Public health practitioners, together with relevant government organisations, should monitor trends in infectious diseases, as well as other relevant indexes, such as vectors, pathogens, and water and food safety. They should advise policy makers of the potential risks associated with climate change and develop public health strategies to prevent and reduce the impact of infectious disease associated with such change. • Doctors and other clinical practitioners should be prepared and supported in the provision of health care for any expected extra cases associated with climate variation and should play an important role in relevant health education on climate change. • Community participation is of significance to adapt to and mitigate the risk of climate change on population health. Community involvement helps to deliver programmes which more accurately target local needs. Therefore, community should be involved in the partnerships of climate change as early as possible. • Relevant education programs on the potential health impact of climate change should be conducted by government at all levels for different stakeholders, including industries, governments, communities, clinicians and researchers. • Advocacy for adapting to and mitigating climate change should be a longstanding public health activity. 2. Implication for researchers • The main task for researchers is to identify the independent contribution made by key climatic variables and whether there are exposure thresholds for infectious disease transmission. Further studies should include various infectious diseases in different climatic regions. • Developing countries and rural regions are more vulnerable to the impact of climate change so more research should be conducted for people living in those regions. • Studies using summary measures that combine prevalence of disease, quality of life and life expectancy, such as Disability Adjusted Life Years (DALYs), to assess the burden of disease due to climate change is necessary to assist in decision making. • More research should be conducted on the assessment of adaptive strategies and mitigation to future climate change. 3. Implication for policies • Public and preventive health strategies that consider local climatic conditions and their impact on vector and food borne diseases are important in reducing such impact due to climate change in the future. • The extra health burden that may be caused by future climate change may have a great impact on the currently overloaded public health system in both developed and developing countries. Long-term planning about health resource allocation, infrastructure establishment, and relevant response mechanisms should be developed at relevant government levels. • Effective prevention and intervention strategies will be possible only if the efforts of relevant sectors, including governments, communities, industries, research institutions, clinical professionals and individuals, have coordinated responses. • International and regional collaborations are necessary to address this global issue. In addition, strategies of an international dimension should be translated into regional and local actions. This is extremely important to developing countries such as China and India. • Sustainable development policies with consideration given to reducing green house gases and environmental degradation need immediate action which will benefit future generations. Health priorities should include the prevention of climate change.
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Thesis(Ph.D.)-- School of Population Health and Clinical Practice, 2007

Introduction: Numerous studies have found associations between exposure to airborne particulate matter and respiratory morbidity and mortality. However, the varying composition, dependant on the different sources of particulate matter, and its effect on processes of inflammation and oxidative stress in the airways has not been completely elucidated. The use of airway biomarkers, fractional exhaled nitric oxide (FENO) and exhaled breath condensate (EBC), can provide valuable insight into processes of inflammation and oxidative stress in the airways. In these studies we sought to characterize the associations between airborne pollutant exposures and their sources and airway biomarkers. Methods:The study population of interest for Chapters III-V is a subset of children currently enrolled in a birth cohort under the Columbia Children's Center for Environmental Health. Chapter III refers to the validation in this population of a method for partitioning FENO contributions from the proximal and distal airways. Chapters IV and V refer to the implementation of this method in the study of ambient metals and residential proximity to relevant sources of particulate matter (PM) and black carbon (BC). Briefly, the children of African-American and Dominican mothers living in low-income NYC neighborhoods had FENO samples collected offline at constant flow rates of 50, 83 and 100 mL/sec at ages 9 and/or 11. Surrogate measures for bronchial flux NO (JNO) and alveolar (Calv) NO concentrations were estimated using a previously validated mathematical model. Wheeze in the last 12 months was assessed by the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. Seroatopy was determined by specific IgE at age 9. For Chapter IV, in order to examine the associations between metal fractions of particulate matter and airway inflammation, ambient measures of Ni, V, Zn and Fe were obtained from a local central monitoring site and averaged over nine days based on three 24 hour measures every third day. Seroatopy was determined by specific IgE at age 7. For Chapter V, residential distance to a major road, truck route and bus stop density, area covered by major roads, stationary point sources (SPS), toxic release inventory sites (TRIS) and commercial buildings, and number of buildings burning residual oil within 250-meters of each child's home were determined. These variables were selected a priori as potential important sources or airborne PM and BC. For Chapter VI, the study population was comprised of seven- and eight-year-old children enrolled in an asthma case-control study in New York City. Seven day averages of domestic levels of particulate matter <2.5 microns (PM2.5), BC and environmental tobacco smoke (ETS) were measured. Urea and 8-isoprostane were measured by liquid chromatography tandem mass spectrometry (LC/MS/MS) in EBC collected during home visits. All data were analyzed with SPSS. Results: In our first study, children with seroatopy had significantly higher median JNO p<0.001) when compared to non-seroatopic children; however, median Calv was not significantly different between these two groups (p=0.644). Children with wheeze in the past year had significantly higher median Calv (p<0.001), but not JNO (295 vs. 165 pL/s, p=0.241) when compared with children without wheeze. In our second study, ambient V and Fe concentrations were associated positively with FENO50 (p=0.018, p=0.027). Ambient Fe was associated positively with JNO (p=0.017). Ambient Ni and V concentrations were associated positively with Calv (p=0.004, p=0.018 respectively). A stronger association of Ni concentrations with Calv was observed among the children with seroatopy. In our third study, there were no significant associations between any of the air pollution indicator variables and FENO parameters in adjusted models. In our final study, PM2.5and BC, but not ETS, were significantly associated with increases in 8-isoprostane (p<0.05 for both) after adjustment for covariates. In a co-pollutant model including PM2.5, BC and ETS, only BC remained a statistically significant predictor of 8-isoprostane. Discussion: Recent exposure to airborne pollutants was associated with increased levels of biomarkers of airway inflammation and oxidative stress measured in exhaled breath. The metal and BC fractions of PM might be more relevant to the understanding adverse respiratory outcomes related to air pollution exposure.

Indoor air quality has become an important health concern due to the number of indoor pollutants and the realization that even minimal exposures to volatile organic compounds may produce direct or indirect adverse health outcomes. Young people are most vulnerable to these poisonous chemicals as they spend much of their times indoors at homes, schools, nurseries and in day care centers. Exposure to volatile organic compounds indoors has been related to asthma and other respiratory symptoms. The adverse effects of air pollution on respiratory health in South Durban have been described in a number of studies. In 2000, a study in the South Durban Basin at Settlers Primary School demonstrated both a high prevalence of respiratory diseases amongst schoolchildren as well as an association between ambient air pollutants and other adverse health outcomes. The South Durban Health Study subsequently undertook a health risk assessment and an epidemiological study investigating this association further on behalf of the eThekwini Municipality. The study highlighted that relatively moderate ambient concentration of N02, NO, PMIO and S02 were strongly and significantly associated with a reduction in lung function among children with persistent asthma. Moreover, attending primary school in South Durban was significantly associated with increased risk from persistent asthma when compared to schools in North Durban. METHODS The descriptive study measured the total volatile organic compound levels within selected homes and schools of asthmatic children in South and North Durban. Recommendations for reducing or mitigating indoor total volatile organic compound exposures were made. The study involved a secondary analysis of data obtained from the South Durban Health Study. The monitoring for total volatile organic compounds within homes and classrooms was undertaken using passive samplers during a 72-hour period and analyzed using a gaschromatography/ mass spectrometry method. Temperature and humidity was assessed using temperature and humidity sensors. Statistical analysis was performed using SPSS version 13. The dataset comprised 140 total volatile organic compound samples from homes and 14 from classrooms. Total volatile organic compounds were measured in microgram per cubic meter (g/m3), temperature in degrees Celsius and relative humidity in percentage of moisture. RESULTS Total volatile organic compounds with levels in households ranging from 17g/m3 to 1440g/m3 and in classrooms ranging from 48g/m3 to 5292g/m3 were measured. The mean levels detected were significantly different in homes and classrooms
Thesis (MMed.)-University of KwaZulu-Natal, Durban, 2008.

Dampness can cause the development of moulds in buildings and pose a threat to the quality of the building structure, indoor air quality and health of the occupants. An emerging source of housing related problems are the building materials commonly used in housing construction, which can influence respiratory health. There is concern regarding the quality of the housing stock in the Durban Metropolitan area with regard to dampness and its the potential impact on the health of occupants. To elucidate this issue, a study was conducted to assess natural ventilation, dampness and mouldiness in dwellings of the Waterloo Housing development (Durban Metropolitan Area), between February 2001 and December 2003. A total of 491 randomly selected homes were visually inspected and residents were surveyed by means of a structured questionnaire. Three hundred and eighteen (318) air and surface mould samples were collected in duplicate, totalling 636 samples and analysed in the laboratory. Building characteristics and physical conditions were recorded and noted. Temperature and relative humidity readings were also taken during the survey. After the analysis of the 491 questionnaires, physical conditions of the dwellings were found to be poor and of concern. With the number (1178) and size of habitable rooms in the dwellings; the occupancy of 2414 people with an average of 2.05 persons per room, indicated overcrowding and congestion. About 51% (n=249) of the dwellings surveyed were found to be experiencing dampness (>3m2) and 47% (n=230) had visible surface moulds, primarily on the walls (at least an average of 1m2) . Predominant airborne fungal organism identified included; Aspergillus (23%-indoors, 26outdoors), Cladosporium (47%- indoors, 51%-outdoors), Penicillum (27%-indoors, 26%-outdoors) spp. Natural ventilation was also inadequate in 261 (53%) dwellings, which did not have airbricks. This inadequacy significantly promotes the occurrence of dampness and surface moulds (p < 0.05). With poor ventilation, dampness and mould growth in the dwellings, there was a high number of cases with upper respiratory tract health complaints; like Cough - 25% (n=122), Sinuses - 25% (n=121), flu symptoms 23% (n=llO) lower respiratory infections such as asthma - 27% (n=130), and chest infections - 23% (n=113). Asthma, wheeze, runny nose and allergy to dust were statistically associated with dampness (p < 0.05), mouldiness (p < 0.03) and lack of ventilation (p < 0.01). Buildings separate their occupants from hostile external environments and create a better internal environment for them, therefore dwellings must be constructed in a manner that promotes the health and well being of the occupants. In terms of guiding regulations, there were several omissions and non-compliance with existing local building bye-laws in the construction of houses, leading to adverse implications. Improved workmanship, appropriate material selection and compliance with the relevant guidelines during planning and construction inter alia, are recommended when addressing housing issues, thereby promoting the interest, health and well-being of the users.
Thesis-(M.Med)- University of KwaZulu-Natal, Durban, 2004.

This thesis is an integrated study that links several disciplines-archaeology, anthropology, geography, atmospheric sciences, and microbiology. It attempts to generate an argument that central to climate change is disequilibrium in human ecologies- in my case, disease ecologies in Iceland during the 15th century. This thesis investigates the environment's effect on human adaptability. The effect of the environment on Icelanders as they moved from settlement to later periods was disquieting. The climate of the world was changing- moving from the Medieval Warm Period to the colder Little Ice Age. I analyze the disease ecology of the 15th century and also conduct an archeological and cultural analysis of the Icelandic people, to show the deficiencies in their adaptation, and submit that certain shortcomings in their physical environment, as well as the inadequate adaptive synthesis to the environment, led to a marginal adaptation. This was augmented by political unrest and problems with outside trade, which left them vulnerable and susceptible to disease pathogenesis. I discuss the climate change during the Little Ice Age, and assert that this event is the crucible that crushed Iceland after 400 years of reasonably good fortune. Hundreds of epidemics, natural disasters, and hardships befall the Icelanders. One of them is the plague, which comes twice in the 15th century. The important observation here is that the epidemiological and archeological evidence does not always match up. The principal problem is that the traditional vector for the disease cannot have survived the climate as it was in the winters during the LIA. I offer an analysis that pontificates this issue and I examine the ongoing debate concerning The Black Death in Europe. I introduce another possible explanation: the introduction of disease through environmental vectors. The creation of disease ecologies through climate change is important, in light of problems that we face today. I discuss the phenomenon of the dust storm and its connection to disease pathogenesis. By showing several key examples of dust from Africa to disease pathogenesis in the Caribbean, I make the connection a good one. In addition to this connection is the atmospheric analysis that shows incontrovertibly that the dust found in Greenland ice cores is only from Asia. Finally, there is the fact that the inveterate loci of the plague bacterium is located in the same areas that Asian Dust Events occur and travel from. I create a methodology for investigating this disease ecology and am able to show that the pathogen can be identified in situ- meaning that it can be found in geological deposits that can be properly dated. My pilot study creates a methodology for the examination of ice cores- the principal reservoir for atmospheric deposits made during the LIA. Finally, I look at the aftermath. I introduce the idea of disease ecology, as opposed to that of a healthy ecology, and suggest by the end of the thesis that within the disease ecology are created many of the platforms for emergent biological changes that translate through evolution over time. Like the bacterium in the ice core, I suggest that evidence for disease states in the history of a people can be found through laboratory techniques. The presence of the CCR5 gene mutation is indicative of such a presence. I believe that the presence of the delta 32 gene mutation found in Icelandic people is the result of being exposed to the plague in the 15th century. This thesis is a platform for future synoptic scale disease studies.
Graduation date: 2005

The use of pheromone-based or semiochemical lures and devices for the detection of insect pest population and monitoring in agriculture is a common practice. In many countries the use of these devices is exempt from registration requirements based on regulatory thresholds set by the relevant authorities, however, not in South Africa. The question arises whether the pheromones or semiochemicals dispensed through such devices, influence the naturally occurring compounds observed and whether a concern of toxicity and ecotoxicity is justified. A tomato field was selected in a commercial growing area of South Africa and a novel five-component lure, T.V. PheroLure®, was identified from a local manufacturer, Insect Science (Pty) Ltd. The T.V. PheroLure® consists of a Volatile Organic Compound (VOC) blend which is placed in a polyethylene bulb. Tomato VOCs were collected before, during and after the application of the T.V. PheroLure® which was used in combination with a yellow bucket funnel trap. The VOCs were collected at different heights (0 cm, 30 cm and 60 cm) of the tomato plants, from planting until harvest (22 weeks) and surrounding tomato fields without the T.V. PheroLure®. The results obtained indicated that: (i) the T.V. PheroLure® had no significant influence on the natural VOCs observed in the tomato field and (ii) that the height of sampling had no influence on VOCs observed. This study also indicated that apart from a slight increased contribution of limonene, there was no significant influence observed from the T.V. PheroLure® compounds on the natural background VOCs found in the tomato field. Therefore, it could be argued that the natural phenology of the plant has a greater influence on the VOCs observed than T.V. PheroLure® and that the concern of toxicity and ecotoxicity is unjustified when using these devices for monitoring purposes only.
Environmental Sciences
M. Sc. (Environmental Science)

This study investigated the prevalences and intensity of intestinal parasites and aspects of their epidemiology among children in the Qwa-Qwa region of the eastern Free St~te. Faecal samples of 1180 children differing socio-economic status from nine schools at altitudes varying from 1660m to 2200m were examined quantitatively by means of the formol-ether sedimentation technique. Socio-economic, and demographic characteristics for the communities served by the schools were obtained from the literature and from a questionnaire. The study showed that, the area supports a markedly low diversity of parasite infections, and at lower intensities, than low altitude areas such as the coastal plain of KwaZulu-Natal and Eastern Cape, the Northern Province, Mpumalanga and the Western Cape. The intestinal parasite fauna affecting children in Qwa-Qwa is dominated by protozoans with only few helminths and no hookworm or bilharzia. The results indicated that factors which influence the transmission of intestinal parasites in Qwa-Qwa appear to be related primarily to social, economic and cultural aspects of the peoples' lifestyles. Climatic factors were not found important. There was a significant seasonal effect on the intensities of all parasite infection, except two protozoans, Entamoeba coli and Endolimax nana. Water source, electricity, house-type and quality of meat were found to be the important socio-economic factors that influenced parasite transmission. These relationships were investigated by fitting logistic regression and generalized linear mixed models. By documenting human parasitism (above 1700m) this study provided an endpoint to the altitudinal transect conducted in 1993 in KwaZulu-Natal by Appleton and Gouws (in press). Public health authorities and Primary Health Care personnel should find this study useful when designing and implementing nutrition and parasite control. Severe ascariasis has been reported from the study area. It will help focus PHC activities in Qwa-Qwa and in the wider context of Free State Province by demonstrating the value of proper personal and environmental hygiene in the home, thereby forming the basis for intestinal parasite control at the community level.
Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1995.

Inorganic arsenic exposure is a well-known toxicant of which we are still discovering harmful effects. People are exposed to inorganic arsenic in the environment through either drinking arsenic-contaminated groundwater or consuming arsenic-contaminated food. Regarding global public health, drinking water is still the most important source of inorganic arsenic exposure and is the main focus of this work. The overall goal of this dissertation is to answer some pointing epidemiological questions about exposure to inorganic arsenic: How much do we know about inorganic arsenic and non-malignant lung disease in the general population? To what extent are adolescents with lifetime arsenic exposure susceptible to the respiratory consequences seen in adults? And what actions can be taken to effectively reduce exposure from arsenic-contaminated drinking water? First, we conducted a systematic review of 29 peer-reviewed articles from various populations around the world. The review focused on the different ways in which arsenic is associated with respiratory health to help inform policy makers and public health researchers on the existing evidence. In short, associations between arsenic and respiratory health were noted throughout the lifespan: in infancy, there was growing evidence that in utero arsenic exposure was associated with increased frequency and severity of respiratory tract infections; in childhood, evidence of respiratory symptoms also began to appear; and in adulthood, there was consistent evidence that arsenic exposure was associated with deficits in lung function and increased reports of coughing and breathing problems. The review also uncovered some research gaps, including few studies with strong exposure history from early life and few studies examining respiratory effects during adolescence. Next, we used a life course epidemiological approach to create a more precise understanding of arsenic exposure and respiratory health during the teenage years. This study examined the relationship between lifetime arsenic exposure and lung function in 14-17 year olds, thus studying the period of maximal lung function before natural decline. Overall, higher arsenic exposure was associated with lower lung function levels; however, these associations were only observed in males. This study used a sensitive marker of lung function to investigate early signs of small airway disease. Incorporating this common marker of small airway disease and airflow limitation in future studies on arsenic and respiratory health may help clarify how inorganic arsenic contributes to the development of chronic respiratory disease. Lastly, we evaluated the effectiveness of arsenic removal filters at the household-level in rural Bangladesh. Identifying sustainable ways of reducing exposure to arsenic from naturally contaminated groundwater has been a major environmental health challenge. Although lab-approved arsenic removal water filters exist, there was limited evidence of their prolonged efficacy in the field. To our knowledge, this was the largest and longest deployment of filters accompanied by monitoring of urinary arsenic. Our results demonstrated that filters can temporarily reduce arsenic exposure for weeks to a few months, but should not be considered as a long-term arsenic mitigation option. This failed attempt to reduce exposure confirmed that alternative mitigation strategies need to be employed in Bangladesh, particularly among more vulnerable populations, including pregnant women and young children. This dissertation has important policy implications for future arsenic research and mitigation efforts and should be effectively communicated to policy makers, public health officials, and the general population. Given the pervasive nature of arsenic exposure and the growing evidence of health consequences at different stages throughout the life course, the continued integration of information on inorganic arsenic and research collaborations across disciplines is critical for the prevention and mitigation of arsenic-induced health consequences.

In order to evaluate the respiratory health status of spray painters exposed to paints containing hexamethylene diisocyanates (HDI) and to obtain more insight into the relationship between occupational exposures to isocyanates and chronic obstructive airway diseases, a follow up study on 33 of an original cohort of 40 randomly selected workers was undertaken. The original investigation was conducted by the author in 1989. The subjects were studied using a standardised American Thoracic Society (ATS) approved respiratory health questionnaire, baseline pre and post shift spirometry and ambulatory peak flow monitoring. Bronchial hyperresponsiveness tests using histamine (PC20) were performed. Immunological tests including IgE, RAST (HDI), and house dust mite evaluations were also made. The subjects were stratified into exposed (n=20), partially exposed (n=5) and no longer exposed (n=7) groups. One subject was excluded from the group analysis because of his indeterminate isocyanate exposure. Warehouse assistants (n=30) in a non-exposed occupation were used as controls. The worker's compliance with safety regulations and the employers provision of safety requirements was assessed by means of a questionnaire. The environmental conditions in the workplace were measured by the evaluation of the isocyanate concentrations at the worker's breathing zone. Spray booth efficiency was measured using measurements of airflow velocities and airflow patterns within the booth. Longitudinal changes in respiratory health status was assessed by comparison with baseline data studied in 1989. The exposed group showed the largest mean cross-shift declines of 297 ml (± 83.8) in forced expiratory volume in one second (FEV1). The decline in the partially exposed group was 282 ml (± 102.7) and 54 ml (± 140) in the no longer exposed group. The results of the first study, when compared with the second study, showed a mean cross-shift decline in FEV1 of 130.5 ml. (± 203) (p=0.0002) and 297ml. (± 323) (p=0.0001) respectively. Furthermore, of the spray painters examined, 10 (25%) showed clinically significant cross-shift declines in FEV1 viz. decreases >250 ml in the first study (n=40) compared with 9 (45%) in the second study (n=33). In contrast to the HDI exposed spray painters, a closely matched control group (n=30) showed a mean cross-shift increase in FEV1 of 17.4 ml ( ± 63.04). Only 2 subjects had a diagnosis of asthma which was made in childhood and not related to occupation. The mean annual baseline decline in FEV1 was greatest in the exposed group 41.25 ml (25% showed a decline greater than >90 ml per annum). These values exceeded the predicted annual declines for both smokers and non smokers due to age. The decline in the no longer exposed group was 7.85 ml per annum. Immunological tests showed no correlation with declines in FEV1 . This study demonstrates the difficulties in correlating immunological status with clinical and lung function findings in workers exposed to HDI, as a means of predicting occupational asthma. Although measurements in cross-shift declines in FEV1 appear to be a suitable predictor of occupational asthma, in some cases it was found that the forced expiratory flow rate (FEF 25-75 %) was a more sensitive predictor of early changes in the small airways. The mean isocyanate concentration in the spray painter's breathing zone was 14.65 mg/m3 (±12.219), exceeding the current South African Occupational Exposure Limit - Control Limit (OEL-CL) of 0.07 mg/m3 for isocyanates. Fifty per cent of the subjects suffered from eye irritation and 40% had dermatitis of the hand. This was expected since none of the spray painters wore goggles or gloves. Whilst no subject had evidence of clinical asthma related to spray painting, a large proportion demonstrated significant cross- shift changes in lung function implying short- term adverse effects of exposure. In addition longitudinal declines in lung function which was worse in those who continued spray painting in the follow-up study, is of major concern. The lack of cases of clinical or occupational asthma may be due to the healthy worker effect. Recommendations include, routine spirometric lung function testing of all spray painters, the use of high volume-low pressure spray guns and the wearing of positive pressure airline masks complying with the South African Bureau of Standards (SABS) safety standard. In terms of current legislation it was further recommended that spray booths be regularly monitored, including the measurement of HDI concentrations, airflow velocities and airflow patterns within the booth and the implementation and enforcement of stricter control measures. Workers demonstrating excessive declines in both cross-shift and longitudinal spirometry, require special attention.
Thesis (M.Med.Sc.)-University of Natal, 1997.

Text in Afrikaans
Summaries in English and Afrikaans
This study aims to investigate the relation between a crane operator in a slab handlingarea's experience of his/her work environment and occupational health. A study of the literature leads one to the conclusion that the nature of crane operators' work environment may cause health problems. According to the literature crane operators are high risk cases regarding musculoskeletal disorders. The empirical study affirms that there are risk factors present in the crane operator's work environment, which may influence his/her occupational health. It is statistically proven that there is a meaningful difference between crane operators with a negative experience of the work environment and crane operators with a positive experience of the work environment, and the amount of illnesses experienced by crane operators as well as their general health. Recommendations are made regarding training, adjustability and flexibility of the work station, job rotation, job expansion and enrichment, and social contact.
Die doel van die studie is om die verband tussen 'n kraanoperateur in 'n platblokhanteringsarea se ervaring van sy/haar werksomgewing en beroepsgesondheid te ondersoek. Die literatuurstudie lei tot die gevolgtrekking dat die aard van kraanoperateurs se werksomgewing aanleiding kan gee tot gesondheidsprobleme. Volgens die literatuur is kraanoperateurs hoerisikogevalle ten opsigte van spierskeletstelselbeserings. Die empiriese studie bevestig dat daar risikofaktore voorkom in die kraanoperateur se werksomgewing wat sy/haar beroepsgesondheid kan be"invloed. Statisties is bewys dat daar 'n betekenisvolle verskil is tussen kraanoperateurs met 'n negatiewe ervaring van die werksomgewing en kraanoperateurs met 'n positiewe ervaring van die werksomgewing en die hoeveelheid siektetoestande wat kraanoperateurs ervaar, en die algemene gesondheid van kraanoperateurs. Aanbevelings om risikofaktore te beheer word gemaak ten opsigte van opleiding, verstelbaarheid en buigbaarheid van die werkstasie, posrotasie, posverbreding en - verryking, en sosiale kontak.
Industrial Psychology
M. Com (Industrial Psychology)

Diarrhoea, particularly infectious diarrhoea, in children below five years of age is recognised as one of the leading cause of morbidity and mortality throughout the world. This is especially true in residential areas of developing countries where there is substandard sanitation and overcrowding which are reservoirs for farther transmission. Shigellosis is endemic in developing countries and in Sub-Saharan Africa, including South Africa, a region where unique geographic, economic, political, sociocultural, and personal factors interact to create distinctive continuing challenges to prevention and control. Our study was undertaken to establish baseline information on incidences of Shigella, its serotype and resistant pattern of isolates from human faeces from residents of Johannesburg, South Africa. All stools received from January to April 2013 from the private health care system were cultured on standard media for isolation of Shigella and confirmed by standard biochemical reactions and serological method. Antibiotic sensitivity test was determined by the agar diffusion method. 11009 stool samples were assayed from patients aged between 22 days to 94 years with a 110 Shigella isolates yield, of which 47 (43%) were S. flexneri, 61 (55%) S. sonnei and 1 (1%) of S. dysentriae and S. boydii respectively. Majority of patients 76 (69%) were children between < 1 to 5 years old followed by those between 6 to 10 years 13(12%). Of the four species isolated from children of up to 10 years old, S. sonnie was confirmed in 52 cases (59%) and S. flexneri in 36 cases (41%). A total of 53 (48%) males and 57 (52%) females were infected. However, a hundred per cent susceptibility to ciprofloxacin and ceftriaxone but high levels of resistance to Co-trimoxazole (83%), tetracycline (72%), and ampicillin (26%) was noted. From the 110 isolates, 96 (87%) were resistant to one or more drugs while 14 (13%) were fully susceptible. These results show that S. sonnei followed by S. flexneri as predominating aetiology of shigellosis and Ceftriaxone and ciprofloxacin as effective drugs against all four Shigella species.
Health Studies
M. Sc. (Life Sciences)

Indoor air quality is described as the chemical, physical and biological characteristics of air in a residential or occupational indoor environment. In residential settings, there are many contributions to indoor pollution levels namely; human activities, biological sources and outdoor air. There has been increased focus on house dust due to its potential to contain biological and chemical pollutants in indoor environments. These have the potential to cause harm to human health. The purpose of this study was to conduct toxicological analysis of house dust collected from inside selected Durban residential buildings. The objectives of this study were to isolate, identify and quantify mould occurrence in house dust samples; to measure the occurrence of heavy metals (arsenic, lead and mercury) in house dust; and to analyse the cytotoxicity of house dust on human lung bronchus carcinoma epithelial line (A549) and human lung bronchus virus transformed epithelial cell line (BBM). One hundred and five house dust samples were obtained from households that participated in the South Durban Health Study. In each home, a sample of settled dust was collected, using standardized protocols, then sieved and individually packed into polystyrene bags. The samples were taken from three surface areas namely; living room couches, bed mattresses, and carpets. Well documented methods were used for the isolation, identification and quantification of mould. The samples for heavy metals analysis were sent to Umgeni Water (chemistry laboratory, Pietermaritzburg) where standardised methods were used. Human cell lines were treated with five different dilutions of each house dust extract. Cell viability was assessed using the MTT assay. Toxic effects of house dust extract were analyzed, following house dust extract treatment and cells were stained with double dye (annexin-V- and propidium iodide) and analysed with flow cytometry, and fluorescent microscope. Cytokines were analysed by Microbionix (Neuried, German) using a Luminex®100 plate reader for multiplex human cytokines analysis. There were (n=128) mould types isolated and (n=105) were identified, of which (n=10) were predominately isolated moulds. This was further confirmed by Allerton Provincial Laboratory in Pietermaritzburg. Among the isolated genera in all three surface areas, Rhizopus spp and Penicillium spp were widely distributed throughout surface areas in greater proportion. The overall highest mean which was reported in this study and expressed in colony forming unit per gram (CFU/g) for Penicillium spp ranged (3400 - 62316 CFU/g) obtained from living room couches, followed by Rhizopus spp (5200 - 15990 CFU/g). The mould results were compared with the South African Occupational Health and Safety Act (OHSA) 85 of 1993 as amended suggested guidelines of 1,000, 000 CFU/g. The findings of this study suggest the moulds in the homes studied were below the suggested guideline. However, this does not imply that the indoor conditions are unsafe or hazardous. Instead, the findings act as an indicator of moulds presence indoors. The type of airborne mould, its concentration and extent of exposure and the health status of the occupants of a building will determine the health effects on an individual. Heavy metals were detected in the dust in the following ascending order: arsenic (As) ranged from 1.3 ug/g -18.4 ug/g (mean, 4.26 ug/g), lead (Pb) ranged from 28.0 - 872 ug/g (mean 171.66 ug/g), and mercury (Hg) ranged from 0.6 -19.0 ug/g (mean, 2.22 ug/g). The mean concentration of lead in the dust was within the range of Canadian National Classification guidelines on residential contamination (500 ug/g). There was numerous numbers of samples in this study that exceeded these guidelines. The mean concentration of arsenic was within residential soil guidelines (20 ug/g). Mercury was within limits when compared with Global Hg project guidelines of soil/residential (6.6 ug/g), thought some of samples were notably above this mean. The ability of house dust extract to lower the cell viability which was slightly above 80% (prior treatment) to less than 50% (post treatment) in both cells was observed in this study. The findings in this study showed that dust extract are toxic to human cell lines, and cells undergone a degree of apoptosis and necrosis 62% (A549) and 99% (BBM). The cytokines serve an important role in the non-specific defence external against insults. It was observed that A549 cells up-regulated the release of IL-6 and IL-8 pro-inflammatory cytokines and under-regulated the release of other cytokines analysed (IL-4, IL-13, and TNF-a). BBM cells released IL-4, IL-8 and IL-13 within limit of detection. The presence of moulds in these sampled indoor household dusts, which is comparable with findings elsewhere indoors, show that moulds act as an indicator for building conditions such as dampness, which supports mould growth. Individuals, whether they are sensitized or not, may develop allergic reactions towards spores, thus the elevated numbers of spores quantified in this study are of concern. Some of the heavy metals reported in this study were higher or marginally higher than international norms and guidelines. The findings in this study strongly suggest that house dust extract is toxic to human lung cell lines. It must be noted, however, that this study may not reflect all that happens when a human lung is exposed to house dust. The findings of this study could contribute to the development of South African indoor air guidelines. In conclusion further study needed to be undertaken with respect to air pollution disease such as allergic; the reason being this study shown the reduced expression of cytokines that are involved in allergic inflammation.
Thesis (M.Med.)-University of KwaZulu-Natal, Durban, 2009.

Introduction. Stone crushing in Dar-es-Salaam Tanzania is largely an informal occupational activity, with approximately 7000 workers exposed to varying level of respirable dust. A highly marginalized, self employed, informal stonecrusher is prone to multiple work related risks, particularly dust related respiratory diseases. Aim. This study, the first to be done among informal stone crushers in Southern Africa, aimed at determining the prevalence of dust related respiratory outcomes and relationships between these health endpoints and exposure to respirable dust in this sample of stonecrushers. Methods. This was primarly a cross-sectional descriptive study with analytic components. This study analysed a subset of data collected in a health survey of stone crushers in Kigamboni informal stone quarry in Dar-es-Salaam, Tanzania in 2007. All 200 workers working in the quarry were interviewed. A subset of 86 and 59 workers underwent exposure assessment and health assessments (spirometry and chest radiography) respectively. Associations were investigated between exposure measures and respiratory outcomes. Results. The average age of the workers was 36.3 years with 51.5% males participating in the study. Smoking was common with 30.1% male, 8.25% female smokers, with 2% ex-smokers. Personal dust sampling showed varying dust levels ranging from 0.5-2.8mg/m3 with geometric mean of 1.2gm/m3. The exposure duration of workers in the quarry ranged from 1-62 years with mean of 7.8 years. No single worker was found to use personal protective equipment at work. Reported prevalence of doctor diagnosed respiratory diseases was low: pulmonary tuberculosis (2%), chronic bronchitis (2%), asthma (3%), pneumonia (3%). In contrast, there was high prevalence of respiratory symptoms: chronic cough (13.5%), phlegm production (14.5%), productive cough (10%), wheezing (14%), mild breathlessness (9.5% ) and coughing blood (7.5%). Mean forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) adjusted for age, height and sex was 2.6L/min and 3.7 L respectively, among males and 2.1L/min and 3.0L respectively among females. Adjusted exposure odds ratios for symptoms were statistically significant for mild and moderate breathlessness with odds ratios of 3.4 and 3.1 respectively. Linear regression showed statistically significant decline of 2.3mls in FEV1 with years of exposure while controlling for sex, age, height , doctor diagnosed TB and smoking showing that with prolonged exposure in the quarry, workers are at a risk of developing obstructive lung disease. This trend was not evident for FVC. The majority of films were normal (60.9%), with 19.6% read as 1/0 and 19.9% as 0/1. Discussion. This study identified adverse respiratory outcomes among informal stonecrushers, particularly a high prevalence of respiratory symptoms and clinically important lung function deficits. These are in keeping with other environment studies where workers were exposed to respirable dust. Recommendations. Urgent policy initiatives for developing cost effective hazard control, engineering interventions to protect these marginalized self-employed informal sector stonecrushers are needed.
Thesis (M.Med.)-University of KwaZulu-Natal, Durban, 2010.

Background: This dissertation comprises research conducted on two distinct projects. Project I focuses on the connection between household air pollution (HAP) from cooking with biomass fuels and blood pressure (BP); this research is situated in the context of a large randomized trial of a cookstove intervention in Ghana, West Africa. The setting of Project II, meanwhile, is the residential environment of New York City, where we explore temperature and humidity conditions in homes and relate these conditions to summertime heat wave risk and to the survival and transmission of respiratory viruses in the winter. Although these projects are quite distinct, each relates to the complex relationship between climate change and health. Reducing HAP to improve health (the focus of Project I) will simultaneously reduce climate change through a reduction in emissions of short-lived climate pollutants into the atmosphere. Meanwhile, furthering our understanding of heat and humidity levels inside urban residences (the focus of Project II) is crucial to our ability to protect health in light of projections for a changing climate. Domestic activities associated with heating, cooling, and cooking are thus very relevant both to human health and to climate change mitigation and adaptation. Objectives and Methods: Our overall objective for Project I was to investigate exposure- response relationships between HAP and BP in a cohort of pregnant women taking part in the Ghana Randomized Air Pollution and Health Study (GRAPHS). We first explored this association in a cross-sectional study (Chapter 1), in which we used 72-hour personal monitoring to ascertain levels of exposure among the GRAPHS women to carbon monoxide (CO), one of the pollutants emitted by traditional wood-fed cooking fires. These exposure data were collected at enrollment into the GRAPHS study, prior to the initiation of cooking with improved cookstoves. We investigated the association between these “baseline” CO exposure levels and the women’s blood pressure at enrollment into GRAPHS. A limitation of this study was that BP was only measured once. We followed this with a second study of 44 women drawn from the same cohort (Chapter 2), for whom we designed BP protocols using 24-hour ambulatory blood pressure monitoring (ABPM), the current gold standard for clinical diagnosis of hypertension. As we were not aware of any prior research in Africa that had employed ABPM, we also designed a parallel BP protocol using home blood pressure monitoring (HBPM) equipment for comparison with ABPM. The use of ABPM with concurrent personal CO monitoring enabled us to investigate hourly associations between CO exposure and changes in BP. We also evaluated BP in these women both before and after the cookstove intervention; this allowed us to investigate whether any changes in BP were associated with switching to an improved cookstove. Our objectives for Project II were to understand the distribution of temperature and humidity conditions in a range of New York City homes during the summer and winter seasons, to evaluate the impact of structural and behavioral factors (e.g. building size, use of air conditioning, and use of humidifiers) on these conditions, and to build models that could help predict indoor conditions from more readily available outdoor measurements. We conducted this research in two ways. We first analyzed a set of indoor temperature and humidity measurements that were collected in 285 New York City apartments during portions of summers 2003-2011 and used these data to simulate indoor conditions during two heat wave scenarios, one of which was more moderate and the other of which was more extreme (Chapter 3). Second, we designed and conducted a new study in which temperature and humidity were monitored in a set of 40 NYC apartments between 2013 and 2015 (Chapters 4-6). This second study enabled us extend our research into the winter season, and also to explore how factors such as air conditioning and humidifier use impacted indoor temperature and humidity. We also investigated relationships between the monitored conditions, self-reported perceptions of the indoor environment, and symptoms that were experienced among household members. Results: In the cross-sectional analysis of CO and BP in the GRAPHS cohort (Chapter 1), we found a significant positive association between CO exposure and diastolic blood pressure (DBP): on average, each 1 ppm increase in exposure to CO was associated with 0.43 mmHg higher DBP [0.01, 0.86]. A non-significant positive trend was also observed for systolic blood pressure (SBP). In our study of the acute relationship between CO exposure and BP (Chapter 2), we determined that peak CO exposure (defined as above the 90th percentile of the exposure distribution, or an average of 4.1ppm) in the two hours prior to BP measurement was associated with elevations in hourly systolic BP (4.3 mmHg [95% CI: 1.1, 7.4]) and diastolic BP (4.5 mmHg [95% CI: 1.9, 7.2]), as compared to BP following lower CO exposures. We also observed a non-significant trend toward lower BP following initiation of cooking with an improved cookstove. Lastly, we demonstrated that ABPM was a feasible and well-tolerated tool for BP assessment in a rural West African setting. For Project II in New York City, we first determined that there was a great deal of variability in indoor summer heat index (HI) between homes in association with similar outdoor conditions, and that this variability increased with increasing outdoor heat (Chapter 3). Our simulation of a moderate heat wave led us to conclude that the hottest 5% of the homes would reach peak indoor heat index (HI) values of 39°C. In a more extreme heat wave simulation, HI in the hottest 5% of homes reached a peak of 41oC and did not drop below 34oC for the entire nine- day simulated heat wave period. Our second indoor monitoring study yielded the following findings: in the summer season (Chapter 4), we found significant differences in indoor temperature and heat index according to the type of air conditioning (AC) in the home. Homes with central AC were the coolest, followed by homes with ductless AC, window AC, and no AC. Apartments on the top floor of a building were significantly hotter than other apartments regardless of the presence of AC. During the winter season (Chapter 5), median vapor pressure in our sample of apartments was 6.5mb. Comparing humidity levels in the apartments to a threshold of 10mb vapor pressure that has been proposed as protective against influenza virus transmission, levels of absolute humidity in the homes remained below this threshold for 86% of the winter: a total of over three months. Residential use of humidifiers was not associated with higher indoor humidity levels. Larger building size (above 100 units) was significantly associated with lower humidity, while the presence of a radiator heating system was non-significantly associated with higher humidity. Lastly, perceptions of indoor temperature and measured temperature were significantly associated in both the summer and the winter (Chapter 6), while sleep quality was inversely related to measured indoor temperature in the summer season only. Reports of heat- stress symptoms were associated with perceived, but not measured, temperature in the summer season. Conclusions: The work presented in this dissertation adds to a growing body of evidence on the importance of exposures in the domestic environment to health and well-being. The research reported here on household air pollution in Ghana documents an exposure-response relationship between air pollution from cookstoves and elevations in blood pressure, on both a chronic and an acute basis. As elevated BP is a known risk factor for cardiovascular disease (CVD), our research provides support for a plausible factor linking HAP exposure to CVD. Meanwhile, our research on temperature and humidity in New York City residences provides concrete data to supplement the very slim literature to date documenting these conditions in the home environment, where Americans spend over half their time. We conclude, first, that AC may not be fully protective against summertime heat risk, and second, that the levels of humidity we observed in residential environments are consistent with levels that have been shown to promote enhanced survival and transmission of respiratory viruses in experimental settings. We suggest that interventions that can reduce exposure to household air pollution and excess indoor heat can also mitigate climate change, and that with thoughtful planning we can improve health at the same time as we foster resiliency in the face of a changing climate.

The phytopathogen Phytophthora ramorum (Werres, DeCock & Man in't Veld), causal agent of Sudden Oak Death (SOD) of oaks (Quercus spp.) and tanoaks (Notholithocarpus densiflorus syn. Lithocarpus densiflorus), is established in coastal forests of the western United States. Since the discovery of SOD in the Douglas-fir / tanoak forests of southwest Oregon in 2001, a multiagency effort has ensued with the goal of fully eliminating P. ramorum from this originally small and isolated area. In this study we investigated the epidemiology of SOD in Oregon, particularly as it affects the success of the eradication program. Two approaches were taken to discern the mechanism of long distance dispersal: first, a landscape analysis of the spatial relationship between SOD sites and roads or streams, features associated with movement of infested soils, and, second, a local analysis to discern if understory infection is originating from soil or stream-borne inoculum. Using a restricted randomization test we concluded that SOD sites were no closer to roads than expected by chance, which is inconsistent with soil dispersal by people. While we found evidence that SOD sites were preferentially closer to waterways, inoculum had not moved away from streams into adjacent understory foliage. The local distribution of understory infection around SOD positive trees indicated that primary inoculum is infecting overstory canopies first, suggesting that P. ramorum is dispersing in air currents. Regression modeling indicated that weather conditions two years before detection could explain variation in the maximum distance inoculum moved each year of the epidemic between 2001 and 2010. This two year delay between infection and detection has allowed ample time for infested sites to contribute to further spread. Model results were consistent with observations made the summer of 2011, when trees likely infected by secondary inoculum at non-eradicated sites developed symptoms but were still undetectable by aerial surveys. Due to the prevalence of infection on tanoak, opportunities for sporulation and infection occur more often in Oregon than in California. These data can explain the failure to eliminate P. ramorum. Nevertheless, we did find evidence that the eradication program has significantly reduced the potential size of the SOD epidemic in Oregon.
Graduation date: 2012

"August 2003."
Includes bibliographical references (leaves 294-333)
2 v. (xxxi, 333 leaves) ; ill. (some col.) ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Thesis (Ph.D.)--University of Adelaide, School of Agriculture and Wine, Discipline of Plant and Pest Science, 2005

Landscape heterogeneity is thought to differ among farm management types (i.e. organic and conventional), and this difference is hypothesized to result in variations in pest control by natural enemies. However, it is unclear if these variations in pest control are driven by landscape structure or by farm management practices themselves. Remotely sensed datasets were used to describe the landscape structure surrounding a group of organic and conventional caneberry farms in Oregon and Washington that have different leafroller parasitism rates attributed to farm management type. A finer scale survey was done at one of the farms using the remotely sensed data as well as field surveys. Landscape metrics of diversity, richness and percent non-crop were used to describe the landscapes surrounding the farm fields at scales ranging from 0.05 km to 5.00 km for the large scale study, and 0.05 km to 0.20 km for the fine scale study. In the fine scale study, data on parasitoid species assemblages, diversity, and parasitism rate were collected and analyzed against the calculated landscape metrics spatially and seasonally. The purpose of this study was to quantify effects of farm management type on habitat structure, effect of habitat structure on leafroller parasitism rate, and to access correlations between landscape metrics calculated at the landscape and field scale. Overall, the farms were embedded in a landscape that was broadly similar, with very few differences in landscape structure occurring between organic and conventional farms. Organic farms had higher vegetation height class diversity at the largest scale compared to conventional farms, while conventional farms had significantly higher percent non-crop area compared to organic farms. There was no significant effect of any of the calculated landscape metrics on parasitism rates. In the field scale study, no correlations were found between habitat metrics and parasitism rates, or between field based metrics and those calculated at the landscape scale. The results of this study suggest that conventional and organic caneberry farms in the Willamette Valley are broadly similar in the habitat conditions they provide parasitoids. This suggests that management changes to pesticide use alone could increase levels of leafroller biological control on conventional farms to levels that are comparable to those seen on organic farms. Our comparisons of the landscape scale and field scale landscape metrics showed no connection, this suggests that direct comparisons cannot be made with these particular metrics at these very different scales. Rather than comparing these types of data, it may be more useful to combine them in order to increase the resolution and predictive power of remotely sensed data for describing landscapes at broad scales.
Graduation date: 2013

Phytophthora lateralis is the causal agent of cedar root rot, a fatal forest pathogen whose principal host is Chamaecyparis lawsoniana (Port-Orford-cedar), a predominantly riparian-restricted endemic tree species of ecological, economical, and cultural importance to coastal Oregon and California. Local scale distribution of P. lateralis is thought to be associated with timber harvest and road-building disturbances. However, knowledge of the landscape-scale factors that contribute to successful invasions of P. lateralis is also important for effective land management of Port-Orford-cedar. P. lateralis is able to infest in wet conditions via stream networks (zoospore) and dry conditions via road networks (resting spore). This study tested the hypothesis that vehicles spread P. lateralis by relating its distribution to traffic intensive, anthropogenic disturbances (i.e. a road network, timber harvest) over a 31-yr period in a 3,910-km² portion of the Rogue River-Siskiyou National Forest in the Siskiyou Mountains of Oregon. Indices of road disturbance (presence/absence, configuration, length, density, road-stream network connectivity) and timber harvest (presence/absence, area, density, frequency) were related to locations of infested cedar populations from a USFS survey dataset using a geographic information system (GIS). About 40% of 934 7th-field catchments were infested with the pathogen. Total road length of the study site was 5,070 km; maximum road density was 8.2 km/km2 and averaged 1.6 km/km² in roaded catchments (n = 766). Timber activities extracted 17,370 ha (2,338 cutting units) of forest across 509 catchments; 345 catchments were cut ≥ twice. Maximum harvest density was 0.92 km²/km² ([mean] = 0.04). Both road networks and timber harvest patchworks were significantly related to cedar root rot heterogeneity. Chi-squared contingency tables showed that infestation rates were 2.2 times higher in catchments with roads compared to roadless catchments and 1.4 times higher in catchments with road-stream intersections compared to those that were unconnected. Infestation was twice as likely in catchments with both harvest and road presence than road presence alone. Single-variable logistic regression showed that a one percent increase in harvest density increased infestation odds 25% and a one-unit (km/km²) increase in road density increased infestation odds 80%. Road and stream network configuration was also important to pathogen distribution: 1) uninfested catchments are most likely to be spatially removed from infested, roaded catchments, 2) only 11% of 287 roaded catchments downstream of infested, roaded catchments were uninfested, and 3) only 12% of 319 catchments downstream of infested catchments were uninfested. Road networks and timber harvest patchworks appear to reduce landscape heterogeneity by providing up-catchment and down-catchment access to host populations by linking pathogenic materials to the stream network. Timber harvest data suggest that while infestation risk to Port-Orford-cedar populations remains high, management policies may have curbed infestation risk in timber-harvested catchments; if this is a result of specific P. lateralis mitigation policies adopted in the late 1980's or broader, region-wide conservation policies (i.e. the Northwest Forest Plan) is yet unclear.
Graduation date: 2012

Introduction: Despite being one of the most preventable diseases, TB still remains a serious and largely neglected disease. Nurses as compared to the general population are at greater risk of acquiring nosocomial TB. This study was conducted to describe the perceptions of nurses on the underlying contributory factors that may lead to the spread of TB in the clinics treating TB patients. Methods: Quantitative, non – experimental, descriptive, exploratory and cross sectional design was used. A structured and pretested questionnaire was used. Findings: The key contributory factors identified were insufficient TB training for staff and lack of knowledge on the TB legislative framework and TB policy directives. Conclusion: The findings indicate the need for a comprehensive TB infection prevention and control policy, with associated standards for provision and practice.
Health Studies
M.A. (Public Health)