A long-term survey on Mycobacterium tuberculosis complex in wild mammals from a bovine tuberculosis low prevalence area

The relevance of wild hosts in the maintenance and transmission of animal tuberculosis may increase as the prevalence in livestock decreases. However, studies on wild mammals in low bovine tuberculosis prevalence scenarios are scarce. The Basque Country is an understudied region from the Atlantic Iberian Peninsula with low bovine tuberculosis prevalence. In this 10-year survey, we searched for Mycobacterium tuberculosis complex (MTC) infection in wildlife and studied the spatial and temporal distribution of the spoligotypes circulating among these wild species and cohabiting livestock. For these purposes, lymph nodes from 1472 wild mammals were cultured and isolates spoligotyped. Information on domestic tuberculosis cases was obtained from the Spanish Database of Animal Mycobacteriosis. Infection was confirmed in ten wild boar (1.12%; 95% CI 0.61–2.05) and four red deer (2.40%; 95% CI 0.94–6.00). MTC was not isolated from badgers or other wild species. The general spoligotype diversity in the region was high. Five distinct spoligotypes belonging to M. bovis (SB0121, SB0134, SB0881, SB2354, SB1086) and one to M. caprae (SB0415) were detected in wildlife. Wild ungulates harboured most of the M. bovis spoligotypes that were commonly found in cattle, being SB0121 and SB0134 geographically associated between wild boar and cattle. M. caprae SB0415 was also found in both wild species as well as in cattle and goats. Despite the absence of MTC-infected badgers and the overall low prevalence observed in wildlife, potential epidemiological links between cattle and wild boar have been revealed. No competent hosts should be ignored when developing global control strategies aimed at eradicating tuberculosis.