Tesi sul tema "Marsupial viruses in Australia"

Four main types of viruses capable of causing systemic and gastrointestinal infections, namely Coronavirus, Rotavirus, Parvovirus or Morbillivirus (Tennant et al, 1991) have been investigated in marsupials. A pilot study to develop and optimise the methodology was undertaken using Canine Coronavirus and the study was then extended to marsupials and other target viruses.In the marsupial portion of the study, a fragment of the correct size for the amplification of pol gene, 409 bp, was obtained from two different faecal samples from tammar wallaby (from Macquarie Fauna Park) and one western grey kangaroo (from Taronga Zoo). The results from tests are studied and compared. It is suggested that future further investigation should be directed at: 1/. Applying the protocols in this body of work to the testing of faecal samples from animals that have been diagnosed as positive with other diagnostic protocols. 2/. Examining more faecal samples from animals that present with active diarrhoea
Master of Science (Hons)

Four main types of viruses capable of causing systemic and gastrointestinal infections, namely Coronavirus, Rotavirus, Parvovirus or Morbillivirus (Tennant et al, 1991) have been investigated in marsupials. A pilot study to develop and optimise the methodology was undertaken using Canine Coronavirus and the study was then extended to marsupials and other target viruses.In the marsupial portion of the study, a fragment of the correct size for the amplification of pol gene, 409 bp, was obtained from two different faecal samples from tammar wallaby (from Macquarie Fauna Park) and one western grey kangaroo (from Taronga Zoo). The results from tests are studied and compared. It is suggested that future further investigation should be directed at: 1/. Applying the protocols in this body of work to the testing of faecal samples from animals that have been diagnosed as positive with other diagnostic protocols. 2/. Examining more faecal samples from animals that present with active diarrhoea

Antechinus is an Australian genus of small carnivorous marsupials. Since 2012, the number of described species in the genus has increased by 50% from ten to fifteen. The systematic relationships of these new species and others in the genus have not been well resolved and a broad phylogeographic study of the genus is lacking. Moreover, little ecological information is known about these new species. Therefore, the present thesis examined the evolutionary biology of Antechinus in two complimentary components. The first component aimed to resolve the systematics and phylogeography of the genus Antechinus. The second component, at a finer spatiotemporal scale, aimed to improve understanding of the autecology, habitat use and risk of extinction within the group, with a focus on the recently named buff-footed antechinus, A. mysticus and a partially sympatric congener, A. subtropicus.

Roads are primary agents of habitat fragmentation and transform landscapes on a global scale. Roads remove habitat and create barriers or filters to the movement of many wildlife species. Moreover, roads disrupt population processes by breaking up continuous populations into smaller, isolated subpopulations or metapopulations, which can suffer genetic drift and become more vulnerable to stochastic processes. Consequently, understanding and mitigating the impact of roads on wildlife has attracted increasing international interest in recent decades. Foremost in efforts to re-connect wildlife populations severed by roads has been the installation of crossing-structures. These are engineered structures designed to provide the opportunity for animals to safely cross either over the road (e.g. land-bridges, rope or wooden canopy-bridges) or under the road (e.g. underpasses, culverts, ecopipes). Crossing-structures enhance the permeability of roads to animal movement thereby improving the ‘functional connectivity’ of the surrounding landscape, or the degree to which the inter-fragment landscape (matrix) facilitates movement. Crossing-structures have thus become a common feature of new road projects in developed countries. Research into the efficacy of crossing-structures is very much in its infancy and has largely focused on assessing whether structures are being used by different wildlife species. As a consequence, we know very little about higher order questions pertaining to population processes, particularly whether the viability of local populations is enhanced by the deployment of crossing-structures. Furthermore, the deployment of crossing-structures has largely focused on terrestrial vertebrates and scant attention has been directed at mitigating road impacts on arboreal mammals, particularly gliding mammals (gliders). This thesis endeavours to address some of these information gaps by presenting the results of a number of investigations into wildlife use of road crossing-structures located in subtropical, eastern Australia. The topics of investigation include: i) glider use of wooden poles on a road land-bridge; ii) home-ranges of gliders residing near road crossing-structures; iii) modelling the effect of connecting habitat patches across road-gaps on glider metapopulation viability; and, vi) determining the effect of road widening on bandicoot use of highway underpasses. They represent the first studies of their kind to investigate such topics. The Australian squirrel glider Petaurus norfolcensis (Marsupialia: Diprotodontia) is a gliding marsupial distributed along the eastern seaboard of Australia. It is listed as threatened in the southern part of its geographic range due to habitat fragmentation. I investigated whether 7-m high wooden poles installed on a land-bridge could enable squirrel gliders to cross a road canopy-gap at two locations in Brisbane, the capital city of Queensland. This represented the first attempt in the world to facilitate road crossing by a gliding mammal in this way. At one location no road crossing was revealed from trapping over a 3-year period. Radio-tracking over 8 months revealed 3 occasions when animals whose home-ranges were aligned along the road had crossed the road. Hair-sampling devices revealed use of the poles at one location during 15 of 20 sampling sessions over a 3-year period, and at the second location during 6 of 6 sampling sessions over a 6-month period. Detection of hair on all poles during some sessions at both locations suggests complete crossings could occur. These observations suggest that wooden poles can be used to facilitate road-crossing by gliding mammals. Obtaining information on the use of novel road-crossing technologies such as gliding poles is a necessary first step to understanding their efficacy. However, the ultimate test of a crossing-structure’s effectiveness is in establishing to what extent has it alleviated the barrier effect of the road and prevented the extirpation of local populations. Accordingly, I utilised the population modelling program VORTEX to assess the viability of a metapopulation of squirrel gliders and Australia’s largest gliding marsupial, the greater glider (Petauroides volans), occurring in forest remnants in the fastest urbanising region of Australia. Population studies were conducted over two years within two of these forest remnants (one small, one large) connected across a major road by a land-bridge with gliding poles and rope canopy-bridges. Whereas I obtained direct evidence of squirrel glider use of the land-bridge poles, it is currently unknown whether greater gliders will use the crossing structures but available tree height and spacing do not allow a glide crossing and fences with metal flashing prevent access to the road by terrestrial and arboreal mammals. My modelling revealed that even a relatively low rate of dispersal facilitated by these structures would substantially reduce the probability of extirpation of the smaller subpopulation for both glider species. This rate of dispersal is plausible given the small distance involved (~50 m). The inclusion of wildfire as a catastrophe in my model suggests that these two remnants may encounter an undesirable level of extinction risk. This can be reduced to an acceptable level by including inter-patch movement via dispersal among other forest remnants. However, this requires connection to a very large remnant 8 km away, through a set of smaller remnants that straddle two motorways. These motorways create discontinuities in forest cover that are beyond the gliding ability of both these species and will require the deployment of crossing-structures to allow inter-patch movement. Whereas our knowledge of wildlife use of road crossing-structures has grown considerably in recent years, little is known about the effect that road widening may have on patterns of use by target fauna. To address this, I investigated the effect that duplicating a highway had on bandicoot (Marsupialia: Peramelemorphia) use of underpasses at Brunswick Heads in north east New South Wales (NSW). This study represented one of the first of its kind in Australia and spanned the period of pre and post-construction over an eight year period. Evidence from trapping data showed that individuals of the two bandicoot species present at the study site (i.e. Isoodon macrourus and Perameles nasuta) incorporated both sides of the road corridor into their home ranges and that the majority of movements were likely associated with foraging. The trapping data also demonstrated spatial overlap between and within sexes and congeners suggesting that underpasses were functionally available to resident animals and were each being used by multiple individuals. Despite this, gaining clear insights on the effect that road-widening had on underpass use by bandicoots was confounded by drought, loss of high quality habitat, a decline in bandicoot abundance, the presence of foxes and different design characteristics of new underpasses. Further surveys are required at Brunswick Heads to elucidate this issue. The results of my investigations on bandicoot and glider use of road crossing-structures provide strong support for the need to manage road impacts on wildlife at multiple scales. At the patch or site-level, a number of enhancements are required to improve the functionality of the investigated crossing-structures and to make the study sites more amenable to the target species. At the landscape-level, management needs to focus on improving functional connectivity in the surrounding landscape to strengthen the viability of local metapopulations. This will require the combination of habitat restoration works, wildfire control and the deployment of crossing structures where large roads and motorways breach forest cover. In the case of gliders, the deployment of crossing-structures can be achieved rapidly and cost-effectively by installing gliding poles along motorway edges and in median strips at locations where forest cover is breached. Future research at these study sites needs to continue for much longer periods (i.e. 5-10 years) and incorporate genetic techniques. This will assist in improving our understanding of the isolation effects of road barriers and whether or not gene flow is restored by the installation of crossing-structures. This should be routinely combined with viability assessments (e.g. PVA) to determine how populations are affected by roads and whether they might benefit from crossing structures. Research is also required to provide insights to dispersal behaviour, particularly for gliders, and the likely use of road-crossing structures. Loss of habitat and habitat connections is continuing in my study landscapes and this is likely to have dire consequences for wildlife if land managers are unable to retain appropriate habitat cover with corridors and install effective wildlife road crossing-structures where large roads bisect wildlife habitat.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
Full Text

Bluetongue disease is an infectious, noncontagious, arthropod-borne disease transmitted by certain species of midges belonging to the genus Culicoides. The causative agent, bluetongue virus (BTV), is a member of the Reoviridae family and orbivirus genus. Although mostly affecting sheep, other ruminants including wildlife can be infected.

The aim of this study was to develop improved methods to detect viable Coxiella burnetii in wastes from livestock production. The impetus for this work arose because there is a significant risk of infection for humans attributed to contact with waste products from the livestock production industry. This situation is further compounded by the lack of suitable tools to detect viable C. burnetii in these wastes. In addition, effective disinfection strategies for livestock wastes are also required to reduce the risk of infection with C. burnetii for individuals that come into contact with these waste products. A quantitative real-time PCR system (qPCR) with high sensitivity and specificity was developed to detect the C. burnetii in environmental samples associated with domestic ruminants and native Australian marsupials. Different detection chemistries and procedures were evaluated based on their sensitivity, specificity and reproducibility. Overall it was found that the TaqMan PCR targeting the IS1111a locus provided the most sensitive and reproducible test. The Geneworks PowerSoil(tm) DNA isolation kit provided the best compromise between reproducibility and recovery of DNA from livestock wastes. When combined, the IS1111a TaqMan qPCR and Geneworks PowerSoil DNA Extraction Kit provided a test which was capable of detecting as few as two C. burnetii genome equivalents in 0.2g of soil or faeces. Coxiella burnetii has been shown to display extreme resistance to environmental exposure. Therefore, assessment of the viability of the organism in environmental matrices is more useful for risk assessment programs than detection of DNA alone. A quantitative reverse transcriptase PCR was developed that was able to detect viable C. burnetii cells in soil. The sensitivity of the assay was enhanced by heat-treating the soil samples prior to extraction of RNA. The factor most often associated with transfer of C. burnetii to humans is exposure to livestock or their waste. Therefore, decontamination of waste from livestock production industries is a key factor in preventing outbreaks of Q fever. A system was developed to determine the efficacy of various disinfectant treatments against the environmental pathogen C. burnetii. Treatments evaluated included sodium hypochlorite, ozone, ultraviolet light, peracetic acid (PAA), and Virkon S®. Sodium hypochlorite at a concentration of 0.1 mM reduced the infectivity of C. burnetii by over 92% while treatment with the same sodium hypochlorite concentration in wastewater showed significantly reduced efficacy. Despite this reduced potency, sodium hypochlorite is still useful for control of C. burnetii in the liquid waste of animal production. Commercially available ELISA and CFT assays exist for ruminants but there are no immunological tests available for detecting C. burnetii in marsupials even though Australian marsupials are known to be susceptible to C. burnetii. An indirect ELISA for detecting anti-Coxiella antibodies in kangaroos was developed. Paired serum and faecal samples were taken from 379 ruminants from Western Australia and the serum was tested with a commercially available ELISA and the complement fixation test while the faeces was tested using the qPCR developed during this study. Paired serum and faecal samples were taken from 343 kangaroos from WA and were tested with the antibody-ELISA developed during this study and by qPCR. A very low prevalence of anti-Coxiella antibodies was observed in the ruminants sampled and results from immunological tests correlated poorly with qPCR data. The development of an ELISA for use with kangaroo serum was problematic because of the lack of reference sera from animals known to be infected with C. burnetii. Despite this results from the ELISA developed suggested that the apparent seroprevalence in the WA animals surveyed was approximately 34%. Results from testing kangaroo faeces with the qPCR correlated poorly with the results from the antibody-ELISA. These data suggest that kangaroos may be a significant reservoir of C. burnetii in Western Australia and due to cohabitation of kangaroos and domestic ruminants, may provide a link between the wildlife and domestic cycles of C. burnetii.

An increasing number of endangered species have reached the threshold prompting management decisions to commence captive breeding and reintroduction. Such intervention is costly and requires a substantial investment of resources that might otherwise be spent on alternate conservation options. It is important, therefore, that such measures make use of all available information to ensure the success of the reintroduction effort, not just in the short-term but also well into the future. The diverse range of elements to be considered include habitat factors, number and sex ratio of founders, number of populations to establish, source populations to use, timing of releases and the need to supplement the populations. All of these factors can benefit through input from molecular genetic data to improve the quality of information used in decision making. Levels of genetic variation are strongly correlated with population fitness and their potential for long-term persistence. For this thesis I examined levels of genetic diversity at neutral and functional regions of the genome for two endangered species of Australian marsupials: the western barred bandicoot, Perameles bougainville; and Queensland populations of the greater bilby, Macrotis lagotis. These two species are under threat from similar processes: habitat destruction and modification for agriculture; predation by foxes and feral cats; changes to traditional fire regimes and competition with introduced pest species. Since European settlement, P. bougainville has become extinct on the mainland and now exists on just two islands in Shark Bay, Western Australia. Macrotis lagotis has suffered a range contraction of over 80% and the Queensland population has become disjointed from other populations to the west. Reintroduction efforts are under way for both species but, until now, the projects have not made use of molecular genetic data to inform their management decisions. I have used marker systems from nuclear microsatellite DNA, mitochondrial control region DNA and the functionally important major histocompatability complex (MHC) to assess levels of genetic diversity in natural, captive and reintroduced populations of both species. DNA was sourced from ear-tissue for P. bougainville and from ear-tissue and faecal pellets for M. lagotis. The levels of microsatellite diversity for the two natural populations of P. bougainville (Bernier Island: HE = 0.27± 0.1, A = 1.8± 0.3; Dorre Island: HE = 0.31± 0.1, A = 2.2± 0.4) were low compared to other marsupials and significantly lower than that recorded for the natural Queensland population of M. lagotis (Astrebla Downs: HE = 0.76 ± 0.03, A = 4.31 ± 0.3). In all cases, the diversity of captive and reintroduced populations was reduced relative to their source populations except for the Dryandra captive population of P. bougainville (HE = 0.54± 0.1, A = 2.69± 0.2) which was founded following a mixed breeding strategy using individuals sourced from both natural island populations. Distribution of mtDNA haplotypes among geographical regions indicated that, for each species, populations could be combined in captive breeding programs without compromising distinct evolutionary lineages. Design of MHC assays proved difficult for M. lagotis, but for P. bougainville two separate MHC class II alleles were identified. These two alleles were fixed across all individuals in all populations suggesting that they may represent two paralogous loci in P. bougainville and that MHC diversity is unusually low for this species. I have recommended that the recovery programs for both species be expanded to incorporate regular monitoring of molecular data to ensure that genetic diversity is retained and maximised in all populations. Where possible, the natural populations should be maintained as “pure lines” to increase overall species genetic diversity but the captive and reintroduced populations should make use of supplementary individuals from a mixture of sources to maximise variation and thus the adaptive potential of these populations in the novel environments to which they are being introduced.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Faculty of Science, Environment, Engineering and Technology
Full Text

Thesis (M. Ed.)--University of South Australia, 1993.
"Report of a thesis submitted for a masters in Education, Human Resource Studies August 1993"--Cover. Includes bibliographical references (leaf 178-188).

The clinical signs and pathology of chronic arthritis-synovitis and chronic interstitial pneumonia in goats in Western Australia were described. Retroviruses were isolated by explant culture techniques from synovial membrane of joints with arthritis, lung tissue of goats with chronic interstitial pneumonia and lung tissue of goats with arthritis but no pneumonic lesions. Similar viruses were also recovered from peripheral blood leucocytes, alveolar macrophages and cells centrifuged from colostrum of goats with arthritis, or arthritis and chronic interstitial pneumonia, by co-cultivation of these cells with normal goat synovial membrane (GSM) cells. The physico-chemical characteristics of the isolated retroviruses were similar to those previously reported for caprine arthritis encephalitis virus (CAEV) which was initially isolated from joint lesions of goats in the USA. These similarities included cultural and morphological characteristics, the presence of RNA-dependent DNA polymerase in the virion, a buoyant density of 1.15 g/ml, similarities in protein composition and antigenic relationship to maedi-visna virus. One property distinguishing the local virus isolates from those described in the USA was the mechanism of virus-induced cell fusion. CAEV-induced cell fusion was previously reported to require de novo synthesis of viral protein in infected cells. Local isolates of CAEV induced cell fusion of GSM cells before progeny virus was detected and de novo synthesis of virus coded proteins was not required. The physico-chemical characteristics of CAEV isolates from lungs of goats with chronic interstitial pneumonia and joints of ii goats with chronic arthritis were indistinguishable. Inoculation of CAEV-free goats with viruses isolated from either type of lesion induced arthritis-synovitis lesions which were similar to those in goats with naturally-occurring disease. None of the isolates from either lung or joint tissue induced interstitial pneumonia in experimentally infected goats, although there was evidence which suggested that lungworms or other granuloma-inducing processes interacted with CAEV to produce chronic interstitial pneumonia. Enzyme linked immunosorbent assays (ELISA), agarose gel immunodiffusion (AGIO) and serum neutralisation tests were developed to detect CAEV-antibody in goats. Goats with antibody to CAEV were persistently infected with CAEV. Serological surveys of goats in Western Australia indicated a high prevalence of infection in dairy goats and a low prevalence in Angora goats. There was no evidence of CAEV infection in feral goats. All CAEV isolates shared common ELISA and AGIO antigens but antigenic heterogeneity was demonstrated using serum neutralisation tests. Antigenic variation of CAEV was shown to occur during persistent infection of goats although the significance of this variation in the pathogenesis of CAEV-induced lesions appeared to be minimal. Ingestion of colostrum and milk from infected does was shown to be a major method of transmission of CAEV, although the virus was also transmitted between older goats during prolonged close contact or mating. This information was used to devise a programme which was successfully used to eradicate CAEV infection from a herd with a high prevalence of CAEV infection.

The use of mathematical models in studying disease epidemics can be diverse, from the focused study of the role of a single determinant of the epidemic, or to the overall estimation of morbidity and mortality. In using simple deterministic models, a balance is struck between biological and social complexities, and the high data input demands of mathematical models. This thesis aims to apply the use of deterministic mathematical models to the studies of HIV and hepatitis C epidemiology in the Asia-Pacific region. In Australia, about 85% of reported HIV cases are among homosexual men. Casual homosexual partnerships made up 40% of incident HIV cases in 1995 increasing to 65% in 2004. In the state of New South Wales, it was estimated that over 7,500 people were living with HIV/AIDS in 2005, increasing to over 10,000 by 2016 with existing levels of intervention. Intervention measures were estimated to have prevented some 44,500 cases, the majority being among injecting drug users through the Needle and Syringe Programmes. Models for the HIV epidemics in developing countries were also developed incorporating multiple routes of HIV transmission. For Papua New Guinea, it was estimated 64,000 people were living with HIV/AIDS in 2005, rising to over 500,000 by 2025 with current levels of intervention. High levels of interventions, in particular increased condom use, will be required to achieve a stabilisation or reduction in HIV prevalence. In East Timor, the HIV epidemic is still in the early stages with 138 people estimated to be living with HIV/AIDS, rising to 5,000 by 2025 with minimal intervention. For HCV, models of the epidemic in Australia showed HCV incidence peaking in 1999, followed by a decline reaching 9,700 incident cases in 2005. Of 197,000 estimated chronic HCV cases in 2005, 58% had stage F 0/1 liver disease, 15% F 2/3 liver disease, and 2% HCV-related cirrhosis. Models estimated 210 and 105 people developed HCV-related liver failure and hepatocellular carcinoma, respectively. Comparisons of modelled HCV long-term sequelae projections with linkage data showed relatively good agreement, despite discrepancies in liver-related deaths. To decrease the number of chronic HCV, at least a tripling of treatment coverage would be required. These models provide estimates of the current levels of epidemics as well as projections of future scenarios under different intervention strategies, which have an important role in the planning of strategies, as well as assessment of previous epidemic conditions.

Respiratory disease is an important cause of wastage in the Australian horse racing industry and viruses are frequently suspected as aetiological agents of respiratory disease or poor performance by clinicians and trainers but confirmation is seldom attempted. This thesis deals with the potential role of equine herpes virus types 1, 2, 4 and 5 in upper respiratory disease and poor performance in horses in Western Australia. The methodology selected for the identification of equine herpes viruses in tissues of horses was polymerase chain reaction (PCR) and therefore individual PCR assays were developed for the detection of each herpes virus, and then a nested multiplex PCR was developed to detect all four viruses. There was good correlation between the multiplex PCR for the detection of EHV and the detection of virus by isolation in cell culture, although a combination of the 2 techniques provided greater sensitivity than either technique alone. The multiplex PCR described appeared equally sensitive as specific PCR assays using a single set of primers for each individual virus but reduced labour and reagent costs. As latency is a well recognised phenomenon in the equine herpes viruses and the horse is subjected to a number of stresses which might induce reactivation of latent infections, it was hypothesised that there would be a background level of replication of the equine herpes viruses in clinically normal horses. Nasal swabs and peripheral blood leukocytes (PBL) were obtained from 282 clinical normal horses and examined for EHV. The results clearly demonstrated the widespread occurrence of EHV in the clinically healthy horses. The rate of detection of different types of EHV varied, as did the prevalence in young and adult horses. The most common EHV detected was EHV5: in 83.2% of 131 of horses <2 years of age; in 40% of horses >2 years of age. A prospective clinical study was conducted whereby respiratory tract samples and PBL from adult horses with respiratory disease and/or poor performance were examined for equine herpes viruses; the aim was to determine a possible association between equine herpes virus infection and respiratory disease and/or poor performance. The relative incidence of factors identified in the history, signalment, physical and laboratory evaluation of horses in the study population was compared between horses from which EHV was identified in respiratory samples and horses negative for equine herpes virus. The results indicated that equine herpes viruses were important causes of respiratory disease in the study population, and that haematological and cytological data were a poor indicator of such equine herpes virus infection. The occurrence of equine herpes virus in nasal swabs and PBL of weaned or unweaned foals from Thoroughbred breeding establishments was determined and provided data on the occurrence of EHV in association with respiratory disease. EHV5 was detected in nasal swabs and/or PBL at a high prevalence rate in healthy foals and yearling horses but its occurrence was not associated with clinical signs of respiratory disease. In contrast, EHV2 was detected more commonly in nasal swabs and/or PBL from foals with respiratory disease than in similar samples from healthy horses. Experimental infection of 8 horses with EHV2 was attempted and induced clinical signs of respiratory disease, but less severe than observed in the epidemiological studies. The results suggested that EHV2 is associated with mild upper respiratory tract infection in young horses.

Monilinia species occur in stone fruit (Prunus species) production areas in many parts of the world, where they cause the serious disease brown rot. Incursion into Western Australia (W.A.) by Monilinia fructicola was declared in 1997, and along with Monilinia laxa has subsequent spread throughout the state has cost the stone fruit industry millions of dollars in lost production and the cost of fungicidal sprays. Until this study, no studies had been made in W.A. of Monilinia species identity, genetic diversity, distribution, virulence, fungicide tolerance or presence of mycoviruses. This project aimed to address these knowledge gaps. A collection of Monilinia isolates was made across the major stone fruit production regions in W.A., and the fungal species were identified. Both species were present, but they were not evenly distributed between and within production regions, indicating the main agent of spread is people. High levels of genetic diversity have been reported for WA population, and both pathogens are not recently introduced in this state. ISSR (Inter Simple Sequence Repeat) markers were used to identify intra-specific diversity in populations, and compare modern populations with the strains that first invaded W.A.. This study revealed that the original incursive strain of M. fructicola has probably become extinct, replaced by new genotypes. Conversely the incursive strain of M. laxa remains widely distributed within the state. New strains appear to have subsequently invaded W.A. and pose ongoing serious threats to the industry. Although commercial stone fruit growers routinely spray their crops with fungicides to control brown rot, small scale and ‘organic’ growers may not. A study was done to assay the relative tolerance to three fungicides of Monilinia isolates collected from sprayed and unsprayed trees. No resistant isolates have been found in WA. Sprayed isolates exhibited a significantly greater range of responses to fungicides than unsprayed isolates, indicating that there is strong positive selection for tolerance in the orchards that routinely apply fungicides. We found there were significant differences between M. fructicola and M. laxa isolates in average tolerance to propiconizole-based fungicides. Assays for virulence revealed the existence of highly virulent, moderately virulent and avirulent strains of both species, and these occurred in both sprayed and unsprayed orchards. On nutrient agar plates, M. laxa isolates presented as four distinct morphologies, while M. fructicola colonies were very similar in appearance across all isolates tested. A survey of 28 isolates of both species revealed three mycoviruses co-infecting three M. laxa isolates and one M. fructicola isolate. The complete or partial sequences of one isolate each of all three viruses was obtained. One M. fructicola isolate was co-infected with all three viruses: Sclerotinia sclerotiorum hypovirus 2 (SsHV2, genus Hypovirus), Fusarium poae virus 1 (FPV1, genus Betapartitivirus), and Botrytis virus F (BVF, genus Mycoflexivirus). To test the influence of these viruses on fungal pathogenicity, several methods were applied to cure isolate M196 of one or more mycoviruses. Of these treatments, hyphal tip culture either alone or in combination with antibiotic treatment generated isogenic lines free of one or more mycoviruses. Morphology and virulence assays were carried out to determine how mycoviruses influence growth of the fungal host. Surprisingly, growth of fungal mycelia was promoted by the presence of three viruses when they were cultured on nutrient agar medium in vitro, but did not influence fungal virulence after inoculation to fruits of sweet cherry.

Thesis (B. Sc.(Hons.))--University of Adelaide, Dept. of Geology and Geophysics, 1991?
Two col. maps in pocket. National grid reference: Coply SH54-9 1:250 000. Includes bibliographical references.

There is increasing concern about hepatitis C virus (HCV) and potential HIV transmission among ethnic Vietnamese injecting drug users (IDUs) in Australia. To date ethnic and cultural differences in vulnerability to blood-borne viruses (BBV) have received little attention and few studies have attempted to explore the role of cultural beliefs and values in influencing injection risk behaviour. This study aimed to systematically explore the cultural beliefs and behavioural practices that appear to place ethnic Vietnamese IDUs at increased risk of BBV infection, identify barriers to this group accessing health and preventive programs, and document antibody HIV and HCV prevalence and associated risk behaviours. The first component of the research consisted of an ethnographic study designed to explore underlying explanatory models of health and illness employed by Vietnamese IDUs and identify cultural influences on risk behaviours and vulnerability to BBVs. These data were subsequently used to inform the development of the instrument used in the second component ??? a cross-sectional survey and collection of capillary blood samples designed to assess risk behaviours and antibody HIV and antibody HCV prevalence. Analysis of data from both components indicates that cultural beliefs and practices influence risk-taking and health-seeking behaviours and suggests pathways through which this influence occurs. Relevant cultural characteristics include those pertaining to spiritual and religious beliefs, the role of the family and traditional Vietnamese family values, cultural scripts of self-control and stoicism, the importance of ???face??? and non-confrontational relationships, trust and obligation, and a reluctance to discuss problems with outsiders. Vulnerability to BBVs is influenced by these cultural characteristics, together with Vietnamese IDUs??? perceptions of risk, knowledge about HIV and HCV, and situational and environmental factors. Main factors contributing to the under-utilisation of health services include the use of self-managed care practices, ambivalence surrounding Western medicine, long waiting times, concerns in relation to confidentiality, stigmatisation of drug use, and limited knowledge of BBVs. The data indicate a need for interventions based on understanding of culturally specific meanings and contexts of health, illness and risk in order to better meet the needs of this vulnerable group.

This thesis investigates the process of habitat fragmentation and the spatial and temporal scales at which it occurs. Fragmentation has become an important topic in biogeography and conservation biology because of the impacts it has upon species??? distributions and biodiversity. Various definitions of fragmentation are available but in this research it is considered to be the disruption of continuity, either natural or human-induced in its origins and operative at multiple spatial scales. Using the distribution of the southern brown bandicoot Isoodon obesulus as a case study, three spatial scales of fragmentation were analysed. At the continental scale, the Australian distribution of the subspecies I. o. obesulus was examined in relation to climate, geology and vegetation cover at the time of European settlement of Australia and two centuries later. Using archived wildlife records and Geographic Information Systems (GIS) analyses, habitat suitability models were created to assess natural and human-induced fragmentation of the distribution of I. obesulus in 1788 and 1988. At the regional scale, a study was made of the distribution of I. obesulus in the south-east of the State of South Australia. Again, natural and human-induced patterns of habitat fragmentation were modelled using GIS with climate, soil and vegetation data for the time of European settlement and at present. At the local scale, the distribution of I. obesulus was the subject of a detailed field survey of 372 sites within 29 remnant patches of native vegetation in south-eastern South Australia in order to understand the variables that cause habitat fragmentation. Geographic information systems were used again but in a different way to carefully stratify the field survey by overlaying maps of topography, vegetation and past fires. The large dataset collected from the surveys was described using six generalized linear models which identified the significant variables that fragment the distribution of I. obesulus at a local scale. From the results of the field surveys, a subset of four remnants was chosen for further GIS spatial modelling of the probability of I. obesulus occurring within remnants in response to fire via a controlled burning programme put in place to reduce accumulating fuel loads. These investigations show that habitat fragmentation can be caused by different factors at different spatial scales. At the continental scale, it was found that climate played a dominant role in influencing the fragmented distribution of I. obesulus but vegetation change during the past two centuries has also had a profound impact on the availability of habitat. Within south-eastern South Australia, the species??? regional scale distribution is constrained by climate and also by soil and vegetation patterns. Dramatic change to its regional distribution occurred in the 20th century as a result of the clearance of native vegetation for planting pastures, crops and pines. Fragmentation at the regional scale has resulted in the remaining habitat being reduced to small, isolated, remnant patches of native vegetation. At the local scale it was found that variables which disrupt the continuity of I. obesulus habitat within remnants include vegetation cover in the 0-1 m stratum, abundance of Xanthorrhoea australis and soil texture. For a subset of sites located in one landsystem of the study area, named Young, the age of vegetation since it was last burnt was also found to be a significant variable, with vegetation 10-14 years old since burning providing the most suitable habitat. Spatial modelling of two scenarios for prescribed burning over 15 years revealed that the use of fire as a habitat enhancement tool will be complicated and require a detailed understanding of the factors that cause natural fragmentation in the distribution of I. obesulus at the local scale. A further conclusion of the study was that ecological relationships between species and their habitats require careful interpretation of multi-scaled datasets and conservation plans for endangered species ought to be made at multiple spatial scales. Future research directions are identified including the linking of multi-scaled habitat fragmentation models to genetic studies of the species throughout its range.

Significant differences in virus incidence were consistently demonstrated between cultivars. 'Victoria' gardens planted with elite (virus-tested) material became almost totally re-infected with PNRSV within eight years. Mechanical inoculation of PNRSV into a range of hop cultivars suggested ' Victoria' was more susceptible than traditional ones. In contrast, the spread rate of HpL V, HpMV, and PNRSV was consistently slower in 'Opal' gardens, and this was found to be the most field resistant cultivar to infection by all three viruses. PNRSV was detected by double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) in chronically infected ' Victoria' plants throughout the growing season. Testing of a range of tissues from 'Victoria' plants suggested a symmetrical distribution ofPNRSV within the plant. Similar testing of 'Nugget', 'Pride of Ringwood', and 'Opal' plants suggested an asymmetrical distribution of PNRSV within the plant. The longer period of elevated virus levels in all tissues in 'Victoria' may increase the probability of virus transmission and be responsible for the accelerated transmission of PNRSV in this cultivar. The asymmetric virus distribution in 'Nugget', 'Pride of Ringwood', and 'Opal' suggested that accurate virus testing relies upon sampling from several hines from each string. Spatial analysis of PNRSV epidemics by ordinary run and radial correlation analyses in 'Victoria' gardens in Myrtleford, Victoria and Bushy Park, Tasmania associated PNRSV transmission with mechanical mowing of basal growth. Transmission was reduced in field trials by preventing basal growth contact between infected and virus-free plants 5 along rows early in the season. This demonstrated that plant contact early in the season increases the probability of transmitting PNRSV to virus-free plants by decreasing the distance infective virions have to travel to infect new plants. Glasshouse trials also confirmed PNRSV to be transmitted by contact and simulated slashing between infected and virus-free plants. Root grafting was also successful at transmitting PNRSV between infected and virus-free plants. The presence of root grafts in Tasmanian hop gardens was suggested by injection of the translocatable herbicide marker, glyphosate. However, quantifi cation of the extent to which root grafts contribute to transmission of all three viruses requires further work. Spatial analysis of carl avirus epidemics showed different distributions between 'Victoria' gardens in Myrtleford and Bushy Park. Random distributions of both HpL V and HpMV at Myrtleford suggested transmission by alatae aphid vectors. Autocorrelated along row distributions of both viruses at Bushy Park suggested transmission by either mechanical transmission through basal growth mowing, and/or aphid vectors (alatae or apterous) directed along rows from basal growth bridges formed through basal growth mowing between rows. A significant positive association between HpLV and HpMV was consistently demonstrated in several cultivars. This may suggest transmission by common aphid vector species, transencapsidation, or the possibility that infection by one virus makes the plant more susceptible to infection by the other. 6 In most hop cultivars grown in Australia the slow rate of virus transmission and significant effect of some viruses on yield of cones and levels of brewing organic acids suggested the continued use of a virus certification scheme for planting stock is warranted. However, in 'Victoria', the usefulness of certification schemes is uncertain because of the rapid spread ofviruses in this cultivar and its tolerance to infection.

The objectives of this study were to investigate the virus incidence and molecular variation of Apple mosaic virus (ApMV), Hop mosaic virus (HpMV) and Hop latent virus (HpLV) and to examine the Hop latent viroid (HLVd) infection status of Australian hop varieties. HLVd was found to be ubiquitous in all hop gardens surveyed. This was the first survey of HLVd in Australia. This confirms findings in the Czech Republic where infection was also found to be ubiquitous, while viroid status in other countries also indicates high levels of infection. A virus survey, primarily to collect viruses for use in molecular analysis, was conducted. The percentage of infected plants detected in this study correlates with those previously undertaken by Pethybridge et al., 2000b. Cultivar ‘Victoria’ had the greatest level of ilarvirus infections (61%) significantly more than ‘Super Pride’ (6%). Cultivar Opal had the greatest incidence of carlavirus infections (38%) but this was not significantly different to other cultivars sampled. Hops from the farm at Bushy Park recorded the highest incidences of Ilarvirus infection (44%) although this was not significantly different to the other sampled farms. However, hops sampled from the Gunns Plains farm showed significantly more carlavirus infections (40%) than the other three sampled farms. Experiments testing transmission capacity of local aphid species (Macrosiphum euphorbiae and Myzus persicae) of the carlaviruses HpMV and HpLV was performed. It was found that both aphid species transmitted both carlaviruses, this being the first study to demonstrate transmission of HpLV by an aphid other than the hop aphid, Phorodon humuli. This study also showed that prior infection by either virus did not significantly affect subsequent the efficiency of transmission of the other which may have explained observations of greater than expected co-infection of both carlaviruses within the field. It was known that two serologically distinct ilarvirus strains infect hop. Prior literature indicated that these were strains of Prunus necrotic ringspot virus (PNRSV) designated –intermediate (PNRSV-I) type and PNRSV-A (apple serotype). This study undertook molecular analysis of hop-infecting ilarviruses to clarify strain diversity and taxonomic relationships. Analyses showed Australian hops are infected with two distinct strains of ApMV (and not PNRSV) these being distinct to ApMV strain commonly found in Apple. It was proposed that hop infecting strains of ilarvirus be termed ApMV-Hop (the former PNRSV-apple serotype) and ApMV-Intermediate (the former PNRSV intermediate serotype). PCR based assays were developed that could be used to distinguish the two strain types. Suggestions of strains of HpMV had been described due to lethal and non-lethal response following infection in ‘English Golding’ hops. Molecular analysis of HpMV from Australian hop gardens indicated that there were at least two distinct clades of HpMV present with approximately 80% homology. Further work conducted at the conclusion of this study identified a possible third clade of HpMV. All HpLV isolates that were sequenced in this study had a high degree of identity. This was supported by recent publication of several further sequences on GenBank that also show this high degree of identity

Bees play an important role as pollinators of angiosperms in most terrestrial ecosystems and they are exposed to numerous threats. In many regions in the world, bee abundance and species richness are in decline due to the combined effects of habitat loss, pesticide use, and parasites and disease. Worldwide, diseases caused by RNA viruses are among the greatest threats to the health of the European honey bee (Apis mellifera) predominantly when the parasitic Varroa mite (Varroa destructor) functions as a vector and incubator of these viruses. While research on RNA viruses in bees has been intensifying around the world, in Australia, information about RNA viruses is limited to managed hives of A. mellifera, but no information is available for unmanaged, wild colonies of A. mellifera, introduced bumble bees (Bombus terrestris) or solitary bees. While knowledge of the distribution of RNA viruses is important in the context of managing and understanding bee declines, it is also important to have baseline data of prevalence and distributions of RNA viruses prior to an incursion of the Varroa mite. The mite is known to influence the infectivity and virulence of different viruses, but so far, baseline data that allow proper monitoring of this process have been scant. Hence, a survey of the RNA viruses carried by Australian bees is timely and necessary. For many decades, A. mellifera has been perceived as the original and only host of a range of RNA viruses. However, recently “honey bee” RNA viruses have been detected in different species of non-Apis bees. This raises questions regarding the original hosts and the direction of transmission of these RNA viruses. Our study confirms the association of some RNA viruses with native bees and show that the probability of South Australian native bees carrying Black queen cell virus (BQCV) and Sacbrood virus (SBV) is higher in non-arid areas with abundant managed and feral A. mellifera. Furthermore, the results indicate that BQCV and SBV were introduced into Australia with A. mellifera. Since the introduction of B. terrestris onto the Australian island of Tasmania in 1992 from New Zealand, no research has been undertaken to determine whether these bees had brought new viruses to the island. Australia is free of a number of RNA viruses including the epidemic Deformed wing virus (DWV), which is present in New Zealand. Using RT-PCR, we found that Kashmir bee virus (KBV) and SBV are present and shared between Tasmanian B. terrestris and A. mellifera, while BQCV was detected only in A. mellifera. Because we did not find DWV in either A. mellifera or B. terrestris, we conclude that introduction of the latter species did not coincide with introduction of this virus. While this is the first report of KBV in Tasmania, we believe it may have been previously detected but misclassified. Recent studies have reported RNA interference (RNAi) as an immune response of A. mellifera to different RNA viruses. The RNAi pathway is activated by presence of doublestranded RNA and degrades the viral genome in 21-22 nucleotides-long small interfering RNAs (siRNAs). siRNAs matching different RNA viruses have been reported in A. mellifera, but generation of a complete viral genome using assembly of siRNAs has not been achieved. Our results show that A. mellifera larvae activate the RNA interference (RNAi) immune response in the presence of SBV. We generate three complete SBV genomes from three individual larvae from different hives in a single apiary, and demonstrated the presence of different SBV quasispecies within the country. In summary, this study provides new insights into the epidemiology and ecology of bee RNA viruses. This information is important for understanding the impact of RNA viruses in bee health and for elaboration of mitigation or control strategies.
Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Agriculture, Food and Wine, 2017.

Cat-borne parasitoses have substantial impacts on livestock, wildlife and human health worldwide. Toxoplasma gondii, Sarcocystis gigantea and S. medusiformis are all cat-borne parasites that share similar biology and ecology, and cause the diseases toxoplasmosis and macroscopic ovine sarcocystosis. I aimed to study the ecology of these cat-borne parasitoses to develop a better understanding of what ecological factors influenced their ability to cycle within an ecosystem. However, it was first necessary to find a study ecosystem where these parasitoses thrived. Using abattoir surveillance data I mapped the occurrence of macroscopic ovine sarcocystosis in the skeletal muscles of sheep across South Australia. Sarcocystosis was highly clustered on Kangaroo Island compared to the South Australian mainland. Second, I investigated if Toxoplasma infection in sheep was associated with macroscopic ovine sarcocystosis to see if I could provide indirect evidence for the clustering of Toxoplasma infection in sheep on Kangaroo Island. Toxoplasma infection was highly prevalent in sheep on the island (56.8%) and was associated with macroscopic ovine sarcocystosis in the oesophagus, but not in skeletal muscles, at the animal- and farm-level. By surveying macropods on Kangaroo Island and the adjacent mainland, I showed that Toxoplasma infection was also higher in western grey kangaroos on the island (20.4%) than on the mainland (0%). This suggested that these parasitoses are well established and thrive on Kangaroo Island and that the island is an appropriate ecosystem in which to study the ecology of these cat-borne parasitoses. Pushing my mapping analyses further, I identified environmental characteristics positively associated with higher densities of sarcocystosis affected locations. The occurrence of sarcocystosis increased at locations with low soil pH and high clay content. I then examined the seroprevalence of Toxoplasma in rodents (Mus musculus and Rattus fuscipes), brushtail possums (Trichosurus vulpecula) and koalas (Phascolarctos cinereus) to explore the impact of the ecology of these species on their risk of infection. Toxoplasma seroprevalence in all species was found to be negligible, suggesting that the intermediate host’s lifespan, feeding ecology and niche influence the parasite’s ability to cycle. To investigate how much cat (Felis catus) abundance may explain the occurrence of these cat-borne parasitoses, I conducted a camera trap survey in both regions and estimated their relative abundance using a simultaneous standardised approach. Cat abundance on the island was estimated to be over ten times higher than that on the adjacent mainland. I suggest that high cat abundance is the primary reason for the high occurrence of cat-borne parasitoses in sheep and macropods on the island, although the ecology of the intermediate host likely influences the ability of the parasites to cycle in these populations. I recommend that the control of cats should be the most effective and acceptable intervention to control these two cat-borne parasitoses in ecosystems where they occur frequently.
Thesis (Ph.D.) -- University of Adelaide, School of Animal & Veterinary Sciences, 2019

The koala (Phascolactos cinereus) is currently listed by the IUCN as vulnerable toextinction with a decreasing population trend. This listing can be attributed to both therecent climate trends impacting ecosystems, and human induced environmental changefrom extensive land clearing and habitat fragmentation. These have both been proven toinduce stress, which in turn influences the onset of disease. This study performed aretrospective analysis whereby admission records for 12,543 wild, rescued koalasadmitted into clinical care within New South Wales were studied in order to determinetrends in clinical admissions and diagnosis over a period of 29 years. Results indicatedthat between all three locations (Port Stephens, Port Macquarie and Lismore), the mostcommon prognosis for koalas admitted into care was disease, the most common diseasefor koalas admitted into care was signs of chlamydia, and the most common outcome forkoalas admitted into care was released. Within Port Stephens, mature aged and femalekoalas were found to have more disease than any other age or gender, while juvenile agedand male koalas were found to be released more than any other age or gender.Additionally, there were fewer koalas with disease and fewer koalas released in PortStephens as each year progressed. Within Port Macquarie, mature aged and male koalaswere found to have more disease than any other age or gender, while juvenile aged andfemale koalas were found to be released more than any other age or gender. Additionally,there were more koalas with disease and fewer koalas released in Port Macquarie as eachyear progressed. Within Lismore, adult aged and female koalas were found to have moredisease than any other age or gender, while joey aged and male koalas were found to bereleased more than any other age or gender. Additionally, there were more koalas withdisease and fewer koalas released in Lismore as each year progressed. Determiningtrends in clinical admissions and diagnosis over such a substantial period of time is animportant determinant for the continuing decline of koalas throughout Australia, and inparticular New South Wales. It is integral that any further decline of koala populations isprevented, however this can only be achieved through informed recommendationsthrough research projects such as these.

The rate of sexually transmissible infections and other blood-borne viruses is high in South Australia. Young people are prone to contracting these diseases who rely on school programs for their health-related behaviours. Health-related behaviours, specifically knowledge and attitudes, can successfully disseminate from teachers to students. Hence, the present study explored the knowledge and attitudes of pre-service teachers in South Australia towards these diseases besides evoking perspectives towards disease-related issues, the role of an effective education thereof, and teacher education in addressing sexual health. The samples (N = 320) comprised of pre-service teachers enrolled in teacher education courses at higher educational institutions in the State. Data collection from the samples took the form of a cross-sectional survey, both at the pilot and the main stages of study. The pilot study was essential to establishing the validity and reliability aspects of the knowledge and attitude scales of the developed questionnaire, which, however, was also measured at the main stage of analysis. A Rasch item analysis using the Quest Version 2.1 software established evidence of a construct validity and an acceptable reliability of both the scales at either stages of study. Subsequent data analysis pertaining to the knowledge and attitudes largely depended on the Rasch estimates being non-parametric, and therefore, the application of non-parametric statistics using the SPSS Version 18.0 software. The open-ended perspectives with 272 valid responses, however, underwent a qualitative thematic analysis. The quantitative analysis revealed a poor level of knowledge (mean score of 18.57 out of a possible 45) and a favourable attitude (mean score of 44.45 out of a possible 51) of South Australian pre-service teachers towards the diseases, with a low to moderate positive relationship between the knowledge and attitude attributes (rs = .196, p < 0.01) [s subscript]. School, peers, and mass media campaigns constituted the major sources of information related to the diseases. There were no significant differences of either the knowledge or the attitude scores across the demographic variables gender, highest educational level, subject stream, and undertaking the related curriculum. However, attitude scores varied across age, with knowledge revealing no significant difference as earlier. The qualitative analysis revealed that the majority of pre-service teachers perceived an information gap and an attitude and behaviour of individuals as primarily responsible for a high disease rate in the State and young people contracting these, respectively. The majority perceived that the related curriculum does not address STI-related issues and that teachers are primarily responsible for the lack of a comprehensive sex education in the State. The majority, however, was largely supportive towards the call for a compulsory sex education. Further, reflecting that they themselves lack adequate knowledge on these diseases, pre-service teachers suggested the introduction of sexual health as a core topic in teacher education. The findings have implications for educators, policy makers, key stakeholders in the field of sexual health education, and the school and the community to raise awareness of the many areas that adolescents and young adults experience problems in, and particularly related to sexual health.
Thesis (Ph.D.) -- University of Adelaide, School of Education, 2013

The South Australian Communicable Disease Control Branch at SA Health is responsible for public health and protection of South Australians through the surveillance and detection of communicable diseases. I was placed within the Branch between 2014 and 2015 as a Masters of Philosophy in Applied Epidemiology (MAE) scholar. In this thesis I present work undertaken during my placement to fulfil the requirements of the MAE. Three of my projects all involved the investigation of Salmonella Typhimurium phage type 9 (STM 9) notifications in South Australia. Notifications of STM 9 have been increasing in South Australia over the past ten years and in 2014 represent a third of all Salmonella notifications in the state. I conducted a data analysis of STM 9 notifications in South Australia between 2005 and 2014. A descriptive and analytical review of notifications was conducted to define trends and changes in the surveillance data and to provide insight into the increase in case numbers. The analysis compared sporadic and outbreak cases and detailed the descriptive characteristics of different multiple-locus variable-number tandem-repeat analysis patterns reported for this phage type. The analysis identified higher notification rates in people living in areas of higher socio-economic advantage and a particular increase in case numbers since 2012. It also identified a large proportion of outbreaks associated with eggs. I conducted a case control study to identify risk factors for sporadic STM 9 notifications in South Australia. This project involved interviewing sporadic STM 9 cases who were frequency matched with controls by age category. The questionnaire explored food, environmental and behavioural exposures. The interim analysis included in this thesis includes 332 participants (40 participants short of the required sample size) and identifies defrosting meat by submerging in water as a potential risk factor and consuming caged eggs as a potential protective behaviour. I investigated an outbreak of STM 9 in a group of school children staying at a campsite in New South Wales while visiting Canberra on a school excursion. The investigation was able to alert other jurisdictions to the potential problem, which resulted in the identification of another affected school group from New South Wales. The cohort study with the South Australian school group was unable to identify a specific source of the outbreak. The environmental investigation conducted at the campsite did not identify any problems and food and environmental samples obtained were all negative for Salmonella. For my remaining project I undertook an evaluation of the South Australian infectious syphilis surveillance system. The evaluation used the Centers for Disease Control and Prevention guidelines to assess ten surveillance system attributes. The impact of three proposed probable case definitions were also assessed. I was able to identify that the system, although highly sensitive, had variable data quality and inconsistencies due to the lack of a systematically applied case definition. Improvements in feedback to external stakeholders were recommended. The probable case definition requiring single high rapid plasma regain cut off greater than or equal to 16, and not requiring a case to have risk factors, had the highest sensitivity.

Includes bibliographical references (leaves 147-171).
xx, 171 leaves : ill. (some col.), photos ; 30 cm.
Studies factors affecting the rate of epidemic progress of cucumber mosaic virus in Lupinus angustifolius.
Thesis (Ph.D.)--Dept. of Crop Protection, University of Adelaide,1992

Bibliography: leaves 129-137
viii, 137 leaves, [27] leaves of plates : 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.)--Dept. of Entomology, Waite research Institute, University of Adelaide, 1986