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Subject: search.filters.subject.Leptospira interrogans

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    Feline leptospiral infection : with particular emphasis on Leptospira interrogans servor ballum : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Veterinary Pathology and Public Health at Massey University
    (Massey University, 1979) Shophet, Rashel
    Following a review of the literature this thesis attempts to study the susceptibility of the cat to different leptospiral serovars. Particular studies were conducted to investigate the pathogenicity, development of the carrier state and the serological response of the cat infected by the oral and intraperitoneal route with Leptospira interrogans serotype balluw. To investigate the hazard of the cat as a carrier and to simulate the field situation of prey-predator chain as a likely source of infection cats were fed infected mice. A serological survey was also conducted to determine the most commonly occurring leptospiral infection in the cat.
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    Leptospirosis in humans and pastoral livestock in New Zealand : a thesis presented in partial fulfilment of the requirements for the doctoral degree of Doctor of Philosophy at Massey University
    (Massey University, 2013) Dreyfus, Anou
    This PhD investigated leptospirosis in humans and pastoral livestock in New Zealand (NZ). A longitudinal ‘abattoir study’, in which blood from workers (n=592) from sheep (n=4), deer (n=2) and beef (n=2) slaughtering abattoirs was tested by the microscopic agglutination test (MAT), revealed that 10-31%, 17-19% and 5% of workers respectively, had antibodies against Leptospira interrogans sv Pomona (Pomona) and/or L. borgpetersenii sv Hardjobovis (Hardjobovis). While the annual infection risk for meat workers of sheep plants was 11.1%, it was 0% in workers processing deer and 1.2% in those processing beef cattle. Sixty workers had a history of probable leptospirosis while working in abattoirs between 1962 and 2010 and three sheep abattoir workers within the one year study period. In sheep abattoirs, new infection with Hardjobovis or Pomona measured by serology was associated with a two-fold higher risk of ‘flu-like’ illness, and an average of four days absence from work. The average annual risk of experiencing flu-like symptoms due to infection with Leptospira measured by serology was 2.7%. The under-ascertainment of officially notified cases with leptospirosis in the last five years was estimated at between 16 and 56 times. Work position was the strongest risk factor for sero-positivity with Pomona and/or Hardjobovis in sheep and deer abattoir workers. The prevalence and new infection risk was highest in workers at the beginning of the slaughter board and the use of personal protective equipment (PPE) appeared not to reduce the risk of sero-positivity or new infection. The risk factor analysis revealed that the infection risk prevailed in the abattoirs and was not evident for non-work related risk factors, such as hunting, home slaughtering and farming. In a multi-species cross-sectional ‘farm study’ (n=238), 97% of sheep and beef and 76% of deer farms had at least one in 20 animals MAT sero-positive against Hardjobovis and/or Pomona. Overall, 50% of adult sheep, 58% of adult beef and 34% of yearling/adult deer were positive against either serovar. Hardjobovis was more prevalent in all three livestock species than Pomona. The regional prevalence distribution in sheep was different for Hardjobovis and Pomona. Grazing beef with deer reduced the likelihood of positivity against Pomona in beef. Co-grazing with another species did not increase the odds of the within-herd prevalence for deer and sheep of Pomona or Hardjobovis and for beef the within-herd prevalence of Hardjobovis controlling for other farm-level risk factors. The incidence of probable leptospirosis in cattle herds in 2009 was 2.6%, in sheep flocks 0% and in deer herds 1%. Tailing rates of sheep farms were positively correlated with prevalence of Hardjobovis: a 1% increase in prevalence was equivalent to a 0.11 increase in tailing percentages, which is unlikely to be causative since this association lacks biological plausibility. All other reproduction and culling rates of any species were not significantly associated with prevalence.
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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.