Abstract:
BACKGROUND : Bovine tuberculosis (bTB) is a chronic debilitating disease and is a cause of morbidity and mortality in
livestock, wildlife and humans. This study estimated the prevalence and risk factors associated with bovine
tuberculosis transmission in indigenous cattle at the human-animal interface in the Serengeti ecosystem of
Tanzania.
RESULTS : A total of 1,103 indigenous cattle from 32 herds were investigated for the presence of bTB using the
Single Intradermal Comparative Tuberculin Test. Epidemiological data on herd structure, management and grazing
system were also collected.
The apparent individual animal prevalence of tuberculin reactors was 2.4% (95% confidence interval (CI), 1.7 – 3.5%),
whereas the true prevalence was 0.6% CI, 0.6 – 0.7% as indicated by a reaction to avian tuberculin purified protein
derivatives (PPD) which is more than 4 mm greater than the reaction to avian tuberculin PPD. The results showed
that 10.6% (117/1,103) showed non-specific reactions (atypical mycobacterium). The herd prevalence of 50% (16/32)
was found. Tuberculin skin test results were found to be significantly associated with age, location, size of the
household and animal tested. Of 108 respondents, 70 (64.8%) individuals had not heard about bovine tuberculosis
at all. Thirty five percent (38/108) of respondents at least were aware of bTB. About 60% (23/38) of respondents
who were aware of bTB had some knowledge on how bTB is spread. Eighty one percent (87/108) of respondents
were not aware of the presence of bTB in wildlife. There is regular contact between cattle and wild animals due to
sharing of grazing land and water sources, with 99% (107/108) of households grazing cattle in communal pastures.
CONCLUSION : The study has demonstrated a high reported interaction of livestock with wildlife and poor knowledge
of most cattle owners concerning bTB and its transmission pathways among people, livestock and wildlife.
Although the overall proportion of animals with bTB is relatively low, herd prevalence is 50% and prevalence within
herds varied considerably. Thus there is a possibility of cross transmission of bTB at wildlife-livestock interface areas
that necessitates use of genetic strain typing methods to characterize them accurately.
