Tuberculosis in found dead badgers at the edge of the expanding bovine tuberculosis epidemic

Bovine tuberculosis (bTB) is a major disease of cattle in the UK, placing a significant economic burden on the taxpayer. The causative agent, Mycobacterium bovis, has a wide host range, including the European badger (Meles meles). While badgers have been implicated in the transmission and maintenance of infection in cattle in areas of endemic disease, their role at the edge of the endemic area is poorly understood. Here we present data on the prevalence of infection in badgers collected along the southern edge of England's bTB epidemic. Stakeholders across five counties (Oxfordshire, Berkshire, Buckinghamshire, Hampshire, and East Sussex) submitted found-dead badgers for post-mortem examination and testing by bacterial culture. The overall prevalence, as confirmed by whole genome sequencing, was 6.5% (28/428), ranging between 1.1% (1/88) in Hampshire and 13.0% (14/108) in Oxfordshire. The commonest M. bovis clade in badgers was B6-62, which was predominant in 4/5 counties. B6-62 was also the commonest clade found in cattle and was detected in all counties except East Sussex where, although absent from the cattle population, it was detected in local badgers. This study highlights the co-incidence of infection in badgers and cattle in parts of the southern edge area consistent with localised clustering of infection in both species.