After immunization of four calves with a live modified Mycobacterium paratuberculosis vaccine the course of the humoral and cell mediated immune reactions was studied during a 2-year clinical investigation. Furthermore, the possibility of shedding of the vaccine strain and the influence of the vaccination on the tuberculin skin test was determined. In addition to standard procedures recently developed diagnostic methods (antibody enzyme-linked immunosorbent assay, interferon-gamma test, polymerase chain reaction) were used. A cell-mediated immune reaction, reflected in an increased, specifically induced, interferon-gamma production developed much earlier (1-2 weeks post-immunization) than humoral immunity (8-16 weeks post-gamma immunization). While the increase in antibody titres was transient, declining to extremely low levels 48-60 weeks post-immunization, cell-mediated immunity remained detectable until the end of the investigation. Spread of the vaccine strain into the body and shedding were never detected during the whole course of the study except for one colon site in one calf. As late as 2 years after vaccine application positive or doubtful skin reactions against M. bovis purified protein derivative were measured, reflecting possible interference of the immunization with the diagnosis of bovine tuberculosis. At the end of the investigation, a positive cell-mediated immune reaction was detected the control animal although clinical, pathological and bacteriological examinations gave no indication for a mycobacterial infection.

In the German state of Rhineland-Palatinate, herds were identified that were likely to have a Neospora caninum sero-prevalence > or = 10% by using a bulk milk ELISA. Individual herd data were obtained by a questionnaire. Univariate logistic regression showed that bulk milk positive farms had a significantly higher chance to report an increased abortion rate than negative farms (P(Wald)<0.1). The chance to have a bulk milk positive herd increased with the minimum number of years a farm had reported an increased abortion rate (P(Wald)<0.1). Questionnaire data, population and dog density as well as climatic data specific for the farm localization were used to identify potential risk factors for a herd to have acquired N. caninum infections. Within an optimized multiple logistic regression model 'Number of farm dogs', 'Herd size', and factors related to the municipality the farm was localized, i.e. 'Mean temperature in July', and 'Dog density' were significant risk factors (P(Wald)<0.1). The present study underlines the role farm dogs have in the epidemiology of neosporosis. In addition, it suggests that the risk a herd has to acquire N. caninum infections is also associated with factors related to the farm location, i.e. factors that are largely out of the control of farmers.

No abstract

In the present study, 132 selected faecal samples from clinically affected and subclinically infected cattle from dairy herds known to be affected by Johne's disease were investigated for the presence of Mycobacterium paratuberculosis using Ziehl-Neelsen staining, faecal culture and a commercially available DNAProbe ® test. The sensitivity was 36.4% for Ziehl-Neelsen staining, 85.6% for faecal culture and 47.7% for the DNA-Probe ® test. Proving the presence of acid-fast bacteria in 49.3% of the samples from clinically affected cattle and 19.3% of those from subclinically infected cattle, Ziehl-Neelsen staining had the lowest detection rate of the three tests under investigation. Faecal culture showed the highest detection rate of M. paratuberculosis in samples from both clinically affected (84.0%) and subclinically infected (87.7%) animals. The DNA-Probe ® test showed a positive result in 68.0% of the samples from clinically affected cattle and 21.1% of those from subclinically infected cattle. Ziehl-Neelsen staining proved unreliable in diagnosing Johne's disease. Faecal culture was the most sensitive method for detecting M. paratuberculosis both in clinically affected and subclinically infected cattle. The sensitivity of a commercially available DNAProbe ® test has to be enhanced to enable a quick and reliable diagnosis of Johne's disease.

No abstract