Mycobacterium tuberculosis infection in grazing cattle in central Ethiopia

A preliminary study to characterise mycobacteria infecting tuberculous cattle from two different management systems in central Ethiopia was carried out. Approximately 27% of isolates from grazing cattle were Mycobacterium tuberculosis, while cattle in a more intensive-production system were exclusively infected with M. bovis. The practice of local farmers discharging chewed tobacco directly into the mouths of pastured cattle was identified as a potential route of human-to-cattle transmission of M. tuberculosis.     

Prevalence of bovine tuberculosis in pastoral cattle herds in the Oromia region,southern Ethiopia

A cross-sectional study of bovine tuberculosis (BTB) was conducted in pastoral cattle herds in southern Ethiopia, from February to August 2008 using the comparative intradermal tuberculin test. The prevalence of BTB and the risk factors for having positive reactor herds were assessed in four pastoral associations in two districts of southern Ethiopia, namely Goro-Dola with 242 cattle in 16 herds and Liben with 231 cattle in 15 herds. A herd was considered positive if there was at least one reactor animal in a herd. The test results were interpreted based on the Office Internationale des Epizooties recommended 4-mm and a recently suggested 2-mm cut-off. The apparent individual animal prevalence of tuberculin reactors was 5.5% (95% confidence interval (CI), 4.0–8.0%) and 7.0% (95% CI, 5.0–10.0%), whereas the true prevalence estimate was 4.4% (95% CI, 0.8–8.0%) and 6.1% (95% CI, 2.6–9.5%), when using the 4-mm and the 2-mm cut-offs, respectively. The overall herd apparent prevalence of tuberculin reactor animals was 41.9% (95% CI, 24.9–60.9%) and 48.4% (95% CI, 30.2–66.9%) with the 4-mm and 2-mm cut-offs, respectively. A positive tuberculin test was associated with the age of animals and the main drinking water sources during dry seasons. In order to investigate the public health risks and the epidemiological importance of BTB in the area, we recommend to include other livestock species (camels and goats) as well as humans in future studies.     

Prevalence study on bovine tuberculosis and molecular characterization of its causative agents in cattle slaughtered at Addis Ababa municipal abattoir, Central Ethiopia

A cross-sectional study was conducted on 500 cattle slaughtered at Addis Ababa abattoir to determine the prevalence of bovine tuberculosis (BTB) and characterize its causative agents. Postmortem examination, mycobacteriological culturing, region of difference-4 (RD4)-based PCR and spoligotyping were applied. The prevalence of BTB was 5 % on the basis of postmortem inspection alone but 1.2 % based on molecular confirmation. Factors including age, sex, and breed showed statistically significant association with BTB (p?<?0.05). Gross lesions were observed most frequently (68 %) in the lungs and lung-associated lymph nodes compared to other organs and lymph nodes. Of the 25 grossly suspicious TB lesions processed and cultured, only six (24 %) were culture-positive, yielding Mycobacterium bovis confirmed by RD4 deletion typing. Further characterization of the six M. bovis isolates at the strain level by using spoligotyping revealed that one did not belong to any previously known type, while the others belonged to types SB1176 (two), SB1477 (two), and SB0133 (one). The new strain was submitted to the international M. Bovis.org database for international code designation. The study confirms the considerable prevalence of bovine tuberculosis in cattle slaughtered at Addis Ababa abattoir and highlights the need for control of bovine tuberculosis in the country.     

Low prevalence of bovine tuberculosis in Somali pastoral livestock, southeast Ethiopia

A cross-sectional study of bovine tuberculosis (BTB) detected by the comparative intradermal tuberculin test (CIDT) was conducted in livestock of the Somali region in southeast Ethiopia??in four pastoral associations from January to August 2009. In 94 herds, each of 15 cattle, camels, and goats was tested per herd leading to a total of 1,418 CIDT tested animals, with 421 cattle, 479 camels, and 518 goats. A herd was considered positive if it had at least one reactor. Prevalence per animal species was calculated using a xtgee model for each species. The individual animal prevalence was 2.0% [95% confidence interval (CI), 0.5?C8.4], 0.4% (95% CI, 0.1?C3%), and 0.2% (95% CI, 0.03?C1.3) in cattle, camels, and goats, respectively. Prevalence of avian mycobacterium purified protein derivative (PPD) reactors in cattle, camels, and goats was 0.7% (95% CI, 0.2?C2.0%), 10.0% (95% CI, 7.0?C14.0%), and 1.9 (95% CI, 0.9?C4.0%), respectively, whereby camels had an odds ratio of 16.5 (95% CI, 5.0?C55.0) when compared to cattle. There was no significant difference between livestock species in BTB positivity. In the present study, the prevalence of bovine tuberculosis was low in Somali pastoral livestock in general and in camels and goats in particular. The high proportion of camel reactors to avian PPD needs further investigation of its impact on camel production.