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    Public health aspects of Yersinia pseudotuberculosis in deer and venison : a thesis presented in partial fulfilment (75%) of the requirements for the degree of Master of Philosophy in Veterinary Public Health at Massey University
    (Massey University, 1992) Bosi, Edwin
    A study was conducted to determine the possible carriage of Yersinia pseudotuberculosis and related species from faeces of farmed Red deer presented for slaughter and the contamination of deer carcase meat and venison products with these organisms. Experiments were conducted to study the growth patterns of Y.pseudotuberculosis in vacuum-packed venison stored at chilling and freezing temperatures. The serological status of slaughtered deer in regards to Y.pseudotuberculosis serogroups 1, 2 and 3 was assessed by Microplate Agglutination Tests. Forty sera were examined comprising 19 from positive and 20 from negative intestinal carriers. Included in this study was one serum from an animal that yielded carcase meat from which Y.pseudotuberculosis was isolated. Caecal contents were collected from 360 animals, and cold-enriched for 3 weeks before being subjected to bacteriological examination for Yersinia spp. A total of 345 and 321 carcases surface samples for bacteriological examination for Yersiniae were collected at the Deer Slaughter Premises (DSP) and meat Packing House respectively. A total of 70 venison sausages were purchased from local supermarkets. Direct plating and plating after 21 days cold-enrichment were carried out to examine for Yersiniae. Venison samples were obtained from the DSP and seeded with a known approximate number of Y.pseudotuberculosis organisms. The samples were vacuum-packed and stored at temperatures of +10°C, +4°C, -1°C, -10°C, -13 ±2 °C,and -20°C; recovery and enumeration of the test organism was made at predetermined times. The results of the Microplate Agglutination Tests showed that deer presented for slaughter at this DSP had low (1:10) or undetectable antibody titres to Y.pseudotuberculosis. The prevalence of Yersinia spp, in faeces was 5.3% (19/360) of Ypseudotuberculosis, 2.6% (9/360) of Y.enterocolitica. 3.6% (13/360) of Y.kristensenii, 20.5% (74/360) of Y.frederiksenii. 0.6% (2/360) of Y.intermedia and 0.6% (2/360) of Y.rohdei. Five of nine strains of Y.enterocolitica isolated were found to be potentially pathogenic by means of the virulence marker tests. Two of them were identified as biotype 3 serovar 0:5,27. There was only one isolation (0.3%) of Y.pseudotuberculosis from 321 carcases sampled at the Packing House. The prevalence of Yersinia spp, in venison sausages was 11.4% (8/70) Y.enterocolitica. 1.4% (1/70) Y.kristensenii and 5.7% (4/70) Y intermedia. Y.pseudotuberculosis grew very well in vacuum-packed venison stored at chilling temperature although a long lag phase was observed at -1°C. When frozen, the organisms remained viable for a long period of time and recovered and multiplied rapidly when transferred to chill temperature. The study showed that there was no serological evidence of yersiniosis in deer presented for slaughter during the study period despite the fact that 5.3% of the animals were carrying Y.pseudotuberculosis in their faeces. While there was a low prevalence of Y.pseudotuberculosis on carcase meat their presence could be a source of cross contamination of other carcases especially during deboning. The finding of Yersiniae in venison sausages showed that there was contamination during their preparation. The multiplication of the bacteria in vacuum-packed venison and their long survival in frozen venison are of public health concern while its presence may affect export markets.
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    A study of Leptospira interrogans infection in deer and goats in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Microbiology at Massey University, Palmerston North, New Zealand
    (Massey University, 1988) Flint, Stephen Harry
    In order to determine the prevalence of leptospirosis in deer and goats both serological tests and the culturing of bacteria from urine samples were used. The serological tests enabled an assesment to be made as to the nature and extent of antibody levels. To ensure confidence in the serological results, it was necessary to validate the standard microscopic agglutionation test (MAT). Repeat tests demonstrated reproducible results that were within one two-fold serial dilution. Enzyme linked immunosorbent assays (ELISA) were investigated as alternatives for both the detection of antibodies and Leptospira antigens. These assays demonstrated greater sensitivity than the MAT for the detection of antibodies, but were less sensitive than standard methods for the detection of antigen. Using the MAT, antibodies to australis, ballum, bratislava, copenhageni, hardjo, pomona, and tarassovi were detected in serological surveys of deer and goats. In deer, the most frequently recorded antibody titres were to ballum, bratislava and copenhageni. As 87% of the antibody titres <80, there appears to be a low level of active infection. In some areas there was a high prevalence of antibody titres to hardjo. In goats, 70% were found to have antibody titres ≥10 to one or more serovars with antibodies to ballum and bratislava the most frequently recorded. As 90% of the antibody titres were <80, there appears to be a low level of active infection in goats. Antibodies to bratislava, a serovar that has not been isolated in New Zealand, were widespread in both deer and goats. The possibility that these resulted from mixed infections was considered but not resolved. Unsucessful attempts were made to purify mixed cultures using specific antisera. The possibility of serological cross reactions of antibodies to other serovars with bratislava was supported by the increased serological response of deer and goats to vaccination with hardjo and pomona antigens. Western blot studies identified several common antigens between bratislava and pomona. A study of a deer farm showed a high prevalence of antibody titres to hardjo corresponding to a similar prevalence of antibody titres to balcanica believed to be due to the antigenic similarity of these two serovars. Balcanica was isolated from urine samples from these deer and is believed to be the first isolation of this serovar from deer. Studies of six goat, farms showed low antibody levels and no Leptospira were isolated from urine samples.
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    Epidemiological studies to inform control strategies for paratuberculosis in farmed deer : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand
    (Massey University, 2010) Stringer, Lesley
    Paratuberculosis, caused by Mycobacterium avium subsp. paratuberculosis (MAP), occurs in a range of ruminant species, and has been diagnosed in wild and domesticated deer worldwide. The disease process in other ruminants is chronic and fatal, with the highest clinical disease incidence generally seen in older animals. However, in farmed deer, disease incidence is highest in young animals, occurring as an acute syndrome in deer as young as eight months of age. The deer industry in New Zealand is concerned about the on-farm impact of paratuberculosis, and the consequences for the venison market should MAP be classified as a zoonosis. Research is thus directed at investigating tools for paratuberculosis control, to reduce the threat to the industry. The aim of the research presented in this thesis was to provide epidemiological evidence that can be used to inform strategy, at industry and farm-level, for control of paratuberculosis in deer. A survey of the deer slaughter population established a baseline prevalence of MAP infection, against which the effects of control initiatives can be measured. Infection was widespread in individuals (45%) and herds (59%), suggesting control rather than eradication as the goal of any industry programme. On-farm disease control was investigated in a randomised controlled trial of vaccine efficacy in young naturally-infected deer. Vaccination reduced the incidence of clinical disease and subclinical pathology; no significant effect on mean production parameters was seen. There was no effect of vaccination on faecal MAP excretion, indicating vaccination may not reduce infection prevalence. Vaccinated deer had an increased risk of testing positively to diagnostic screening tests for bovine tuberculosis. Non-specificity was resolved by ancillary testing, but such tests come at an increased financial and test sensitivity cost. Paratuberculosis control at the industry level may involve schemes to classify herd infection status. For this purpose, the sensitivity and specificity of individual faecal culture and an IgG1 ELISA (Paralisa) to detect young deer infected with MAP was estimated using Bayesian latent class analysis. Paralisa and faecal culture had sensitivity of 19%and 77%, and specificity of 94% and 99%, respectively. Improved diagnostics are therefore needed if herd infection status is to be classified in a sensitive, specific, cost-effective and timely system. The studies contribute to knowledge on different aspects of paratuberculosis control in the New Zealand farmed deer population, providing an evidence base for informed decisionmaking at farm and industry level.