Towards harmonised procedures in wildlife epidemiological investigations: A serosurvey of infection with Mycobacterium bovis and closely related agents in wild boar (Sus scrofa) in Switzerland

Bovine tuberculosis (bTB) is a (re-)emerging disease in European countries, including Switzerland. This study assesses the seroprevalence of infection with Mycobacterium bovis and closely related agents in wild boar (Sus scrofa) in Switzerland, because wild boar are potential maintenance hosts of these pathogens. The study employs harmonised laboratory methods to facilitate comparison with the situation in other countries. Eighteen out of 743 blood samples tested seropositive (2.4%, CI: 1.5-3.9%) by ELISA, and the results for 61 animals previously assessed using culture and PCR indicated that this serological test was not 100% specific for M. bovis, cross-reacting with M. microti. Nevertheless, serology appears to be an appropriate test methodology in the harmonisation of wild boar testing throughout Europe. In accordance with previous findings, the low seroprevalence found in wild boar suggests wildlife is an unlikely source of the M. bovis infections recently detected in cattle in Switzerland. This finding contrasts with the epidemiological situation pertaining in southern Spain.