Herd-level risk factors of bovine tuberculosis in England and Wales after the 2001 foot-and-mouth disease epidemic

We present the results of a 2005 case–control study of bovine tuberculosis (bTB) breakdowns in English and Welsh herds. The herd management, farming practices, and environmental factors of 401matched pairs of case and control herds were investigated to provide a picture of herd-level risk factors in areas of varying bTB incidence. A global conditional logistic regression model, with region-specific variants, was used to compare case herds that had experienced a confirmed bTB breakdown to contemporaneous control herds matched on region, herd type, herd size, and parish testing interval. Contacts with cattle from contiguous herds and sourcing cattle from herds with a recent history of bTB were associated with an increased risk in both the global and regional analyses. Operating a farm over several premises, providing cattle feed inside the housing, and the presence of badgers were also identified as significantly associated with an increased bTB risk. Steps taken to minimize cattle contacts with neighboring herds and altering trading practices could have the potential to reduce the size of the bTB epidemic. In principle, limiting the interactions between cattle and wildlife may also be useful; however this study did not highlight any specific measures to implement

Standardization of a technique for analysing the frequency of parasite-specific cytotoxic T lymphocyte precursors in cattle immunized with Theileria parva

A limiting dilution microculture system was optimized to quantify the frequency of Theileria parva-specific cytotoxic T lymphocyte precursors (CTLp) in peripheral blood mononuclear cells (PBMC) from immune cattle. Optimal results were obtained with responder cell input levels ranging from 2 x 10(4)/well to 6.25 x 10(2)/well, along with 1-5 x 10(3)/well stimulator cells in standard supplemented RPMI 1640 medium containing 2.5-5% T cell growth factors. Thirty-six microtitre wells were established at each responder input level. Cultures were incubated for 7 days at 38-degrees-C, at the end of which time individual wells were screened for cytotoxic activity in a 4-h indium-111 oxine-release assay. Analysis of the cytotoxicity data, by a computer-programmed maximum likelihood estimation method indicated that they conformed to the Poisson model of single-hit kinetics. Estimates of frequencies ranged from 1:3600 to 1:5275 CTLp in PBMC of eight cattle between 1 and 24 months after immunization with T. parva. By contrast, no CTLp were detected in six naive animals analysed to a responder cell input of 10(5)/well. Split-well analysis of individual microwells showed that the CTL clones generated under limiting dilution conditions displayed exquisite specificity for parasitized cells, were genetically restricted and in some animals were parasite strain-specific

Lymphoid changes in African trypanosomiasis

Meeting: Conference on Recent Advances in the Knowledge of Pathogenicity of Trypanosomes, 20-23 Nov. 1978, Nairobi, KEIn IDL-329

Parasitemia and host susceptibility to African trypanosomiasis

Meeting: Conference on Recent Advances in the Knowledge of Pathogenicity of Trypanosomes, 20-23 Nov. 1978, Nairobi, KEIn IDL-329

Changes in the immune system during experimental African trypanosomiasis

Meeting: Conference on Recent Advances in the Knowledge of Pathogenicity of Trypanosomes, 20-23 Nov. 1978, Nairobi, KEIn IDL-329