PhD Research Students

CURRENT PROJECTS

Aspects of the pathogenesis of Mycobacterium paratuberculosis infection in sheep

Kate Bower (nee Goldsmith)
Research support: Meat & Livestock Australia
Supervisors: Professor R Whittington, Dr D Begg

Johne’s disease is characterised by a lengthy incubation period, measured in years. It is well known that cows with severe infections commonly shed the causative organism, Mycobacterium paratuberculosis, into their milk, and may also infect their unborn calf in utero. The organism can be isolated from extra-intestinal sites in such cases. There is a smaller body of evidence for this in sheep, but infection of tissues outside the gut is recognised in advanced cases in rams and ewes. The means by which the organism reaches sites outside the gut is uncertain, but may involve transfer via blood. The aim of this project is to identify extra-intestinal transfer of the organism during experimental and natural Johne’s disease infections in sheep.

Apoptosis in sheep with Mycobacterium paratuberculosis infection

Sally Browne
Research support: Meat & Livestock Australia
Supervisors: Dr K de Silva, Associate Professor D Emery

Johne’s disease is a chronic wasting condition of ruminants caused by Mycobacterium avium subsp. paratuberculosis (Mptb). Clinical disease is seen only in adult animals. More knowledge regarding the pathogenesis of this disease, including apoptotic responses during the course of infection, is needed to allow advances towards management and control of Johne’s disease. The aim of this project is to develop assays for detection of apoptosis in sheep then define apoptotic responses in sheep with OJD. In initial experiments, Merino sheep aged 7 months were orally dosed with the organism and samples were taken of many tissues. At this very early stage in the development of Johne’s disease, there were no significant differences in the percentage of caspase positive cells when lymph node cells were incubated in the presence of medium alone or Mptb antigen. However, at day 6 with Mptb antigen, cells from gut lymph nodes in animals exposed to the highest dosage tended to have a higher percentage of caspase positive cells than the medium controls. Cells from peripheral lymph nodes incubated with Mptb for 6 days had higher apoptotic activity than the medium only controls, regardless of exposure to Mptb. These results suggest that detecting apoptosis in response to Mptb antigen in vitro in lymph node cells may be useful in identifying animals exposed to Mptb. Further studies are being carried out at later time points in the disease.

Immunopathology and development of diagnostic test for early detection of Johne’s disease in cattle and sheep

Ratna B Gurung
Research support: Endeavour Postgraduate Award, 2009 (EPA 2009)
Supervisors: Professor R Whittington, Dr A Purdie, Dr D Begg

Johne’s disease also known as paratuberculosis mainly in cattle and sheep is a chronic condition affecting intestines. It has worldwide distribution with varying prevalence in different countries. Dairy industries are badly affected in many developed countries. Due to the economic implications from loss of production it has become a concern for all. Although many diagnostic tests are available, they have their own limitations. Tests with low cost, as well as better sensitivity and specificity for early detection of disease are needed to improve the currently available diagnostic approach. Early detection of the disease will benefit farm profitability and welfare of subclinically affected animals.
In pursuit of identifying potential candidate antigen for use in diagnostics as well as vaccine development, this study will focus on various antigens from the causative agent genome. Detailed study of immunological values will be done on the identified antigens that will be used for future diagnostic tests for early detection of disease. This study is also prospecting collaboration between international institutions for some parts of the research component. The established research facility at the Faculty of Veterinary Science at Camden within the Johne’s disease projects supported by MLA, will be the main research station for the entire study.

Immunogenic and pathogenic aspects of Mycobacterium avium. Subsp. paratuberculosis specific cell wall Lipopentapeptide

Shyamala Thirunavukkarasu
Research Support: University of Sydney World Scholars Award
Supervisors: Professor R Whittington, Dr K de Silva, Dr K Plain

Paratuberculosis caused by Mycobacterium avium subsp. Paratuberculosis (Map) is one of the most important causes of morbidity in ruminants leading to huge economic losses worldwide. Control of mycobacterial infections requires the development of a Th1 type T cell response. The innate immune responses are believed to be triggered by pattern recognition receptors, such as toll like receptors (TLR). Several studies have shown that mycobacterial components act as TLR agonists. Lipopentapeptide is component found only in the cell wall of Map and is absent in the cell wall of other mycobacterial species, hence it is unique to Map. This project will study the immunogenicity of lipopentapeptide and the interaction of lipopentapeptide with TLR and the resultant impact it has on the pathogenicity of the organism. Studying this would be useful in understanding the pathogenesis of Map as well as to determine if this Map specific lipopentapeptide could have any putative diagnostic and therapeutic value.

The sheep/ Haemonchus contortus relationship

Kate McMaster
Research support: Meat and Livestock Australia.
Supervisors: Associate Professor N Sangster, Dr K Bosward

Haemonchus contortus is one of the most economically important parasites in the Australian sheep industry. In recent years resistance to parasitic drugs has forced both sheep producers and researchers to look for alternative means of parasite control. A better understanding of the host parasite relationship is an essential step in discovering improved control measures. The balance of the host parasite relationship shifts depending on the status of the host, for example age or reproductive status, and how the parasite responds. Studying the development of the protective immune response of the sheep when infected with Haemonchus will enable a better understanding of the host-parasite relationship and should provide the means to measure the development and mechanisms of immunity and resilience to infection. This will indicate whether we can predict or modulate the response towards protection or test the host’s “resistance status” for selection purposes. It is hoped that this investigation will provide producers with another tool to manage parasitic infections without resorting to anthelmintic treatment.

Investigation of various aspects of ovine footrot control by specific vaccination

Vidya Bhardwaj
Research support: Australian Wool Innovation
Supervisors: Dr O Dhungyel, Professor R Whittington

A research team based at the University of Sydney has been established to achieve eradication of ovine footrot by specific vaccination. Ovine footrot is caused by many different serotypes of the bacteria Dichelobacter nododsus. Effective immunity is provided by vaccinating against 2 serotypes only at a time. To achieve eradication of disease, a flock is serotyped and a specific vaccination used to eradicate that serotype.

Currently, a small percentage of sheep in a flock fails to respond to the vaccination. Our studies will investigate if this failure to respond is due to the host immune status or due to the nature of the footrot vaccination. Footrot is manifested either as a benign form or a more virulent one in a herd. A study of the protein structure of virulent bacteria is expected to show significant differences from the benign strains. This can then serve as a diagnostic tool to predict the severity of an outbreak. Evaluations of various sample sizes will show the smallest number of animals that are required for sampling to give a statistically significant result.

Topical anaesthesia in livestock- reducing pain and stress and enhancing wound healing and production

Sabrina Lomax

Research support: Jean Walker Fellowship Fund (APA equivalent), Australian Research Council Linkage grant, Animal Ethics Pty Ltd, Bayer® Australia.
Supervisors: Professor P Windsor, Professor P Wynn,
Dr Meredith Sheil

Livestock husbandry procedures including mulesing, castration, tail-docking and dehorning cause considerable pain and suffering, yet are routinely conducted in Australia without the employment of anaesthesia or analgesia. While these procedures may be justifiable for animal health and management reasons, there is growing consumer concern, both nationally and internationally, regarding the infliction of pain on animals. This has the potential to significantly impact Australia’s exports as consumers move to select alternative products or those from more welfare conscious markets. This could not be more evident than in the current mulesing debate that has put the Australian wool market under intense scrutiny by international importers. The growing pressure to select wool from un-mulesed sheep has led to an industry push to phase out the procedure by 2010 should a viable solution not be found.
Our research group aims to develop industry and consumer acceptable methods of pain management in livestock husbandry, as well as introduce novel methods of pain assessment in animals. We have been conducting studies over the past 2 years on the application of a spray-on topical anaesthetic formulation, Tri-Solfen®, to the wounds inflicted by mulesing, castration and tail-docking. We have assessed wound sensitivity using Von Frey Hair stimulation, measuring local involuntary reflexes and central cognition. These responses were graded using a numerical rating scale (NRS). Observation of behavioural responses to pain was also conducted, along with a novel technique to assess wound healing which involved digital photography and computerized surface area measurement.

The Use of Topical Analgesia for Improving the Welfare of Livestock Following Invasive Husbandry Procedures

Crystal Espinoza
Supervisors: Professor P Windsor and Dr G Cronin

Animal husbandry procedures such as castration, tail-docking and dehorning are routinely performed on millions of animals worldwide each year. Such procedures are performed for varying reasons including animal health, for facilitating management and for the safety of farm workers. While the conduct of these surgical procedures are important in commercial animal production, the procedures cause pain and distress and are traditionally performed without anaesthesia or analgesia. The main limitation to currently available pain relief options is that they involve too much time, expense and labour and thus are not be economically viable for commercial production.
An alternative solution may be the use of topical local analgesia in the form of a liquid substance containing local anaesthetics, which is applied during or immediately after a surgical procedure. Topical analgesia is more practical and affordable than current options and has the potential to be fast-acting and highly effective. Topical analgesia has recently been found to alleviate the pain associated with castration and tail-docking in lambs and calves, and mulesing in lambs. It is hypothesised that its application can be successfully expanded to surgical procedures applied to other production species. Findings from this research have the potential to improve the welfare of production animals, which has become a critical issue in modern society.

Assessing pig movement and associated risk of Classical Swine Fever transmission in Eastern Indonesia

Edwina Leslie
Research Support: Australian Centre for International Agricultural Research (ACIAR), Pork CRC, Dinas Peternakan, Kupang
(West Timor)
Supervisor: Dr J-A Toribio
Associate Supervisors: Professor M Ward and Dr M Geong

ACIAR has developed a project to improve understanding of livestock movement and the risk of spread of transboundary animal diseases. The component in which PhD student Edwina Leslie will be involved focuses on Classical Swine Fever (CSF) in Eastern Indonesia, specifically Nusa Tenggara Timor (NTT). Hog Cholera, as it is locally know, was first confirmed in NTT in 1998. Since its introduction, this virus has produced high mortality rates for the pig populations across most of this province. Pigs have a significant cultural role within this area and thus there has been a severe economic impact for local communities as a result of this disease.
Formal movement of pigs will be investigated through interviews with pig sellers and pig buyers in markets. Informal movement of pigs will be investigated through village interviews with pig farmers. Risk assessment and social network analysis of their movement, in addition to identifying key pig management techniques, is expected to contribute to the development of government policy to minimise and control spread of CSF.

Epidemiological investigations into the 2007 equine influenza outbreak in Australia

Simon Firestone
Research Support: Australian Biosecurity Cooperative Research Centre for Emerging Infectious Disease, Rural Industries Research and Development Corp.
Supervisors: Dr N Dhand, Dr J-A Toribio, Professor M Ward

This project is designed to investigate the characteristics of the 2007 equine influenza (EI) outbreak in Australia in order to improve our understanding of the factors contributing to the spread of the outbreak and contribute to preparedness for future incursions of animal diseases in Australia. The research team, based at the University of Sydney, includes partners from government (NSWI&I, QDPIF & DAFF) and industry (RIRDC).
A case-control study is underway, involving collection and analysis of data from 200 horse premises from highly affected regions of New South Wales. The aim is to investigate risk factors for the spread of EI onto premises, in particular non-compliance with biosecurity measures as recommended by animal health authorities at the time of the outbreak. This will be followed by an in-depth analysis of the features of the epidemic using spatial epidemiological approaches to compare the intensity of transmission of EI between several geographic regions, under different management conditions and operation types. The project also involves network analysis of data of horse movements during and after the outbreak. It is envisaged that the project will help refine guidelines to assist disease control authorities make informed decisions in the event of a future incursion of EI in Australia. Detailed analysis of the spread of EI may also yield critical insights into the ecology and transmission of influenza viruses in general in naïve populations.

The 2007 outbreak of Equine Influenza in Australia- an investigation of policy implementation and horse owners’ biosecurity behaviours.

Kathrin Schemann
Research Support: Australian Postgraduate Award, Rural Industries Research & Development Corporation, NSW Department of Industry and Investment
Supervisors: Dr N Dhand, Dr J-A Toribio, Dr M Taylor, Professor M Ward

In 2007 Australia experienced its first outbreak of Equine Influenza (EI), causing substantial financial and emotional hardship to horse owners and industry participants. The use of biosecurity measures represents a major means of control for highly infectious diseases. This project aims to investigate horse owners’ biosecurity perceptions and the factors driving their biosecurity behaviour in light of the 2007 outbreak. The information gathered during this project will inform extension activities targeted at the horse industry to improve disease awareness and biosecurity practices.
In addition, the project will investigate the implementation of the EI AUSVETPLAN, the national policy document describing the Australian approach and proposed control measures to manage an outbreak of EI. We will investigate factors influencing policy implementation, such as epidemiological information available at the time of the outbreak, media coverage, logistics, economics, animal welfare and lobbying. Elucidation of these factors will inform disease control authorities on how to improve policy development and implementation for potential future outbreaks of exotic infectious diseases.

Iridoviruses of fish

Anneke Rimmer
Research support: University of Sydney Postgraduate Scholarship in Iridoviruses in the Murray Darling Basin
Supervisors: Professor R Whittington, Dr J Becker

Viruses within the family Iridoviridae have emerged as a major threat to the aquaculture industry and native finfish of Australia. Recently there has been a growing concern regarding the introduction of exotic ornamental fish viruses, in particular dwarf gourami iridovirus (DGIV) to Australia via the transmission pathway of imported ornamental fish.Iridoviral diseases are known to be important in aquaculture, with DGIV having caused significant losses of farmed Murray cod fingerlings in Victoria in 2003. The range and effect of DGIV and other iridoviruses on wild populations of native fish in Australian waterways is largely unknown. Accordingly this research project aims to increase the knowledge of iridoviruses which may be present in Australia’s Murray Darling river system through the development and evaluation of tools for studying iridoviruses of fish, determining the range and effect of iridoviruses in Australia and determining the properties of DGIV. The outcomes of this research will be beneficial to industry, inform policy and facilitate the necessary ongoing protection of the Australian aquatic environment through conservation management and assessing the quarantine risks associated with iridoviruses and imported ornamental fish.

Iridoviruses of ornamental fish and implications for Australian marine species

Jeffrey Go
Research Support: Australian Post Graduate Award and Vice Chancellor’s Research Scholarship
Supervisor: Professor R Whittington

Iridoviruses, particularly those of the genus Megalocytivirus, have been associated with mass mortalities in a range of cultured finfish species throughout Asia. Additionally, this group of viruses have been reported from a range of fish species in the ornamental fish trade. In 2003, a Megalocytivirus associated disease outbreak occurred in a Victorian Murray cod farm. This represented the first occurrence of this viral group in Australian aquaculture, although the outbreak was contained and the disease subsequently eradicated from the facility. The extremely close genetic relationship between the viral isolate involved in this outbreak, and Megalocytivirus isolates from ornamental fish suggests that the ornamental fish trade was the most likely origin of this virus. Recent research also suggests that marine fish may be susceptible to infection with Megalocytivirus isolates from the ornamental fish trade, which could have severe implications for Australian marine ecosystems and emerging Australian marine aquaculture industries.

A research project is currently underway to further characterise the nature of Megalocytivirus infections and to test the susceptibility of a number of Australian marine finfish using material originating from the ornamental fish trade. The project will also aim to develop improved diagnostic tests for this group of viruses including in situ hybridisation, and serological tests such as enzyme linked immunosorbent assay.

Healthy Dogs Healthy Communities - Approaches to knowledge sharing education to sustain dog health initiatives in remote Indigenous communities

Sophie Constable
Research Support: Australian Postgraduate Award, Australian Research Council Linkage Grant
Supervisors: Dr RJ Dixon, Dr RM Dixon

Dog poor is poor in many remote Indigenous communities compared to urban and rural averages. The Healthy Dogs Healthy Communities Program aims to explore current dog and community health as well as investigating the effect of dog health and dog health education programs.

This study aims to evaluate the use of education as a health strategy by identifying and analysing factors that lead to a successful culturally relevant, evidenced based, generative curriculum education program in 6 remote Indigenous communities. It is expected that the results of the project will enhance effectiveness and sustainability of future dog health and community health initiatives in remote Indigenous communities.

Understanding and mitigating domestic pig and wildlife interactions

Hayley Pearson
Research support and funding: Australian Pork Limited
Research support: Invasive Animals CRC
Supervisors: Dr J-A Toribio, Dr S Lapidge

Wildlife has been a source of emergent disease for livestock, causing billions of dollars of economic impact. There are a number of diseases in domestic pigs that were sourced from wild animal hosts. As domestic pigs may come into contact with a range of wildlife species in Australia this project firstly aims to determine what animal species are most frequently observed in and around piggeries and are of concern to commercial piggery owners in Australia. This will be determined by responses to a postal questionnaire that will be distributed to all commercial piggery producers in Australia via Australian Pork Limited. Further aims of the project include determining whether there are interactions between domestic pigs and wildlife species, whether these wildlife species are carriers of diseases infectious to the pigs, and determining whether the wildlife are the possible source of infection in the pigs. It is expected that this project will significantly contribute to the understanding of how wildlife contribute to the disease load on pig farms. The specific outcomes are expected to be recommendations to producers and the industry as a whole on mitigating risk.

Understanding the risks of Foot-and-mouth disease to Australia: modelling disease spread in feral and domestic animal populations

Katherine Negus
Research support: University of Arizona
Supervisor: Professor M Ward

Our ability to detect and appropriately respond to emerging and exotic diseases is critical for Australia’s biosecurity. However, there remain large gaps in our knowledge of the potential spread and areas of greatest risk for such disease occurrences, thus limiting our preparedness. Considerable effort, particularly recently, has been applied to modelling animal disease spread via livestock movements. However, the disease threat from wild animal (feral and native) and unfenced livestock populations that might form disease reservoirs has received comparatively little attention; such uncontrolled animal populations can represent a considerable proportion of the entire susceptible animal population for a variety of diseases. These populations can exacerbate outbreaks, form reservoirs of disease, and might allow novel diseases to become endemic.

Specific key outcomes – improve our understanding of the potential spread of FMD in Australia by using a spatial disease spread model within a geographic information system framework; and identify critical risk factors that predict the outcome of FMD incursions, in order to improve surveillance and control strategies. Research components – disease risks maps will be developed to illustrate criticality of locations to incursions of FMD by performing a semi-quantitative risk analysis; population surfaces for susceptible animal populations will be developed; a series of targeted simulations will be run to identify the possible spread from likely disease initiation points; those conditions (environmental and population) that can lead to larger outbreaks of disease will be characterized and the model used to evaluate different management strategies to mitigate disease spread.

Framework for evaluating economics of the decision making processes related to the development of animal health emergency plans and policy in Australia

Sarah-Jane Wilson
Research support: Australian Government Department of Agriculture, Fisheries and Forestry
Supervisor: Professor M Ward

Literature will be reviewed, including the history of emergency animal diseases, the new livestock revolution, globalisation, and the drivers of animal health policy. Policy making in Australia related to emergency animal diseases (government and industry perspectives) will be explored, via a survey of current attitudes and approaches to decision making and policy development, focused on members of the CCEAD and peak industry body representatives. Follow up interviews with participants will then be undertaken. A gap analysis will be used to identify areas of commonality or divergence. Current methods used for decision making in policy development will also be considered. Examples in cost-benefit analysis, linear programming, partial equilibrium analysis, input-output models and social accounting matrices. Sociological assessments (political, moral and ethical) will also be considered. Event analysis will be used to understand what paradigms we have about what methods we currently use, reasons for a focus on technical frames of analysis, and the issue of cost recovery and emergency cost mitigation (versus compensation). Relevant AUSVETPLANs will be examined. The resulting framework(s) development will be validated using case studies on disease emergencies that represent a range of issues - such as actual versus theoretical incursions, industry type, trade, environmental concerns, zoonotic disease threats and consumer benefit. Case studies will be undertaken on foot-and-mouth disease, Varroa, equine influenza and Hendra virus.

The Spatio-Temporal Epidemiology of Rabies in Bhutan

Tenzin
Research support:
University of Sydney International Scholarship, Australia
Supervisors: Professor M Ward, Dr N Dhand

Rabies is endemic in southern Bhutan. Domestic dogs, especially strays, have been the main source of infection of domestic animals and humans. Rabies causes economic losses to farmers and the government in the form of loss of livestock and the cost associated with the prevention and control measures. Therefore, it is important to understand in detail the epidemiology of rabies in Bhutan. The following epidemiological aspects of rabies will be studied as part of the PhD research program:

• Geographical Information System and spatial analytical techniques will be used to describe and generate hypotheses for the spatio-temporal distribution of rabies occurrences in animals in Bhutan.
• Molecular and phylogenetic analysis: rabies virus genotypes will be characterised by laboratory examination of suspected brain samples, gene sequencing and then phylogenetic analysis. The genetic characterization of rabies virus has not been previously studied in Bhutan.
• Knowledge, attitudes and practice (KAP) survey: a cross-sectional study using a structured questionnaire survey will be carried out in one of the rabies endemic areas of Bhutan to determine the level of people’s knowledge, attitudes and practices of rabies and rabies control activities including rabies vaccination, various aspects of dog ecology and the relationship between dogs and humans in the area.
• The epidemiology of dog bite incidence in humans in Bhutan: there is a large number of stray dogs and dog bite (whether normal or suspected rabid) is common, especially in urban areas of Bhutan. A retrospective (hospital based post exposure treatment database) and prospective (cross sectional questionnaire survey) study will be completed to understand the epidemiology of dog bites in humans.
• Risk assessment: currently rabies is endemic only in the southern part of Bhutan. We will estimate the chance of spreading the virus into the interior part of the country through risk-pathway analysis.

The information generated from this study will help in designing a rabies prevention and control program for Bhutan.

Australian National Surveillance System for Animal Health (ANSSAH)

Emma Fuller
Research support: Australian Biosecurity Cooperative Research Centre for Emerging Infectious Disease
Supervisors: Dr N Dhand, Dr M Hernandez Jover, Dr A Cameron,
Mr I Langstaff

The aim of Australian National Surveillance System for Animal Health (ANSSAH) project is to enhance Australia’s capacity to provide timely information on animal health status. This will be achieved by drawing on innovative methodologies to develop a national system for the collection, storage, analysis and reporting of health information. The project will draw on the current National Animal Health Information System (NAHIS) and incorporate existing and potential data sources for surveillance that have varying degrees of utilisation. Stakeholders will be consulted about their specific requirements of surveillance information are what data is needed to meet those requirements. The ultimate outcome of the project is to implement a system that takes an active role in disease detection and surveillance data analysis and better positions Australia to address future animal health surveillance challenges in relation to livestock productivity, market access, public health, food safety, wildlife health and biodiversity.

Cambodian field veterinary services and bovine health, with an emphasis on improved FMD control

John Stratton
Research support: Australian Biosecurity Cooperative Research Centre for Emerging Infectious Disease, Australian Centre for International Agricultural Research
Supervisor: Professor Peter Windsor

The descriptive component comprises visiting Cambodian village animal health workers who are semi-skilled para-veterinarians responsible for delivering village veterinary services. Also involves analysing information on village animal health-worker training, their contact with farmers and the government, and their knowledge and experiences of the two most important diseases of Cambodian cattle and buffalo, haemorrhagic septicaemia and FMD, both of which are endemic by utilising village animal health workers to field trial FMD vaccination in the face of outbreaks.