SUMMARY: Techniques have been established for the generation of bovine cytotoxic T cell lines and clones specific for lymphocytes infected with the protozoan parasite Theileria parva. Theileria-specific cytotoxic T cell lines are generated by repeated stimulation in vitro with atttologous T. parva-infected ceils, of peripheral blood mononuclear cells from cattle immunized with T. parva. Theileria-specific cytotoxic T cell clones can be derived from these restimulated cultures by limiting dilution of the cells in the presence of irradiated stimulator and filler cells and T cell growth factor. The clones have the BoT4-BoT8 ~ phenotype and are restricted by class I MHC products. Parasite strain specificity of the clones differed depending on the parasite stock used for immunization, and in some instances differed between individual animals immunized with the same parasite stock. Preliminary evidence suggests that the latter is due to an influence of the MHC phenotype of the animal. Results of the parasite strain specificity of the cytotoxic T cell response are consistent with findings of cross-immunization experiments with the two stocks of the parasite studied.

BackgroundThere is paucity of information regarding the epidemiology of Escherichia coli O157: H7 in developing countries. In this study, we investigated the occurrence of E. coli O157: H7 associated with beef cattle at processing plants and at retail shops in Ethiopia.MethodsVarious samples were collected from beef cattle at slaughter/processing plants, carcass at retail shops and humans at health centers. E. coli O157: H7 was isolated, identified and characterized for antimicrobial resistance, using standard microbiological methods.ResultsAt the processing plants E. coli O157: H7 was detected in 1.89% of fecal, 0.81% of intestinal mucosal swab, 0.54% of skin swab and 0.54% of carcass internal swab samples. At retail shops it was detected in 0.8% of carcass and 0.8% of cutting board swab samples, while all samples from utensils, hands from workers, and fecal and stool samples were negative. All isolates were resistant to Amoxicillin, moderately resistant to Cefoxitine and Nitrofurantoins but susceptible to other antimicrobials tested.Conclusions E. coli O157: H7 occurs at low prevalence in beef cattle, and the current sanitary dressing procedures in the processing plants and storage conditions in the retail shops are effective against E. coli O157: H7.

Background: Ethiopia bears the largest burden of foodborne diseases in Africa, and diarrheal diseases are the second leading causes of premature deaths. Enterohemorrhagic Escherichia coli O157 causes an asymptomatic infection to severe diarrhea and/or hemolytic-uremic syndrome in humans. Methods: A total of 440 beef carcass and in-contact surface swabs from 55 butcher shops and 85 minced beef samples from 40 restaurants in central Ethiopia were collected and examined for the presence of E. coli O157. Standard microbiological methods were used to isolate and identify E. coli O157 and to characterize the antimicrobial resistance of the isolates.Results: E. coli O157 was detected in 4.5% carcass swabs (n = 5) and 3.6% cutting board swabs (n = 4) samples from butcher shops. E. coli O157 was not detected in any of the minced beef samples obtained from restaurants. All isolates (n = 9) were 100% susceptible to five drugs, but five isolates were resistant to amoxicillin, two isolates to streptomycin and three isolates to chloramphenicol. One isolate was resistant to two drugs and another to three drugs.Conclusions: The present study shows a low prevalence of E. coli O157 in beef sold at butcher shops. Nevertheless, given the low infective dose of this pathogen and the deep-rooted tradition of consuming raw or undercooked beef, the current prevalence should not be considered lightly from a public health perspective.