Abstract
Introduction Mycobacterium bovis infects a wide range of wild and domestic mammals. This study examines the epidemiology of M. bovis in pigs and correlates it with cattle and badgers. Materials and Methods: TB-suspect lesions identified in pigs at British abattoirs between 2007 and 2011 were sampled and mycobacterial isolates identified by culture and spoligo-/VNTR-typing. The geographical distribution of M. bovis and M. avium cases was determined; M. bovis isolates were also mapped against the equivalent genotypes in cattle and badgers. Data regarding the age/number of affected pigs, herd size, anatomical location of lesions and opportunity for contact with wildlife or cattle were also collected. Results Nationwide, TB lesions are as likely to be caused by M. avium (11.7% of TB-suspect lesions) as M. bovis (12.8%). However, in the South-West (SW) and West Midlands (WM) regions, M. bovis predominates (86%). Although similar genotypes occur in cattle and pigs, opportunities for direct contact between these species are rarely observed. Mapping data indicates that one strain in pigs may correlate better with the corresponding cases in badgers. M. bovis is more commonly seen on farms where pigs are kept outdoors or wildlife may have access to pens (77.4%). Conclusion M. bovis is the major cause of TB-suspect lesions in pigs in the SW and WM regions. Breakdowns are most common on farms with lower biosecurity; furthermore one M. bovis genotype correlates better with badger data, than cattle. Pigs may therefore represent a useful sentinel for this strain in the wildlife.