The prevalence of bovine tuberculosis (Mycobacterium bovis) infections in feral populations of cats (Felis catus), ferrets (Mustela furo) and stoats (Mustela erminea) in Otago and Southland, New Zealand

Twenty-one properties in the Otago region of the South Island of New Zealand were surveyed for the presence of gross lesions due to Mycobacterium bovis infection in feral cats (Felis catus), ferrets (Mustela furo) and stoats (Mustela erminea) during 1993 and 1994. In total, 1293 cats, ferrets, stoats and weasels (Mustela nivalis) were examined for the presence of tuberculous lesions. The properties surveyed were selected according to the history and incidence of bovine tuberculosis infection in their cattle herds. Sixteen infected cattle properties were trapped in areas of Otago that were endemic for bovine tuberculosis and five properties were trapped in non-endemic areas that were considered to be free from tuberculosis infection in the cattle. No tuberculous cats, ferrets, stoats or weasels were found in non-endemic areas, and prevalence rates in the endemic areas were 0.9% for cats (n=215, 0.12<mu<3.6 at 95% CI), 17.9% for ferrets (n=548, 14.9<mu<21.5), and 1.6% for stoats (n=62, 0.04<mu<8.95). Bovine tuberculosis was not found in any of the four weasels examined. A statistically significant association (p=0.019) was shown between the prevalence of tuberculosis in ferrets from infected properties compared to uninfected properties. High prevalences of bovine tuberculosis in ferrets, the geographically widespread nature of bovine tuberculosis infections in ferrets, and the association of tuberculous ferrets with infected cattle herds suggest that ferrets may transmit infection to domestic stock.