A study of tuberculosis in road traffic-killed badgers on the edge of the British bovine TB epidemic area

Abstract

The role of badgers in the geographic expansion of the bovine tuberculosis (bTB) epidemic in England is unknown: indeed there have been few published studies of bTB in badgers outside of the Southwest of England where the infection is now endemic in cattle. Cheshire is now on the edge of the expanding area of England in which bTB is considered endemic in cattle. Previous studies, over a decade ago when bovine infection was rare in Cheshire, found no or only few infected badgers in the south eastern area of the county. In this study, carried out in 2014, road-killed badgers were collected through a network of local stakeholders (farmers, veterinarians, wildlife groups, government agencies), and Mycobacterium bovis was isolated from 21% (20/94) badger carcasses. Furthermore, there was strong evidence for co-localisation of M. bovis SB0129 (genotype 25) infection in both badgers and cattle herds at a county scale. While these findings suggest that both badgers and cattle are part of the same geographically expanding epidemic, the direction of any cross-species transmission and the drivers of this expansion cannot be determined. The study also demonstrated the utility of using road-killed badgers collected by stakeholders as a means of wildlife TB surveillance.

Temporal and spatial Mycobacterium bovis prevalence patterns as evidenced in the All Wales Badgers Found Dead (AWBFD) survey of infection 2014–2016

“…However, females without bite wounds were only half as likely to be infected with M. bovis compared to males without bite wounds. This contrasts with the findings www.nature.com/scientificreports/ from the Cheshire study which reported that no badger carcasses had obvious bite wounds whilst conceding that it was possible that the carcass damage caused by vehicular collision or post-mortem scavengers might have masked their presence 10 . Previous studies have suggested that transmission via biting is possible during aggressive encounters between male badgers 21 and that badgers with advanced disease are more likely to be bitten due to a loss in social status and competitive ability increasing susceptibility to aggressive behaviour from other badgers in their resident and neighbouring social groups 22 .…”

“…A more recent study of bTB in badgers in England also supports the sampling of found-dead badgers as a means of establishing TB status in wildlife, observing a co-location of M. bovis genotypes in both badgers and cattle herds in Cheshire 10 . Here we describe the results of the AWBFD survey undertaken between September 2014 and December 2016.…”

Molecular Detection of Arthropod-Borne Pathogens in Eurasian Badgers (Meles meles) from the United Kingdom

“…In the meantime, these were stored at 4 °C. Sex and age (juveniles or adults) of each carcass was recorded and based on body mass and dental wear as previously described [12]. Both blood and heart samples were collected from eight of the badgers, while for 10 animals only the heart was available ( Table 1).…”

“…Badgers may have an epidemiological role in infections of veterinary and public health importance, including the rabies virus, and most notably, bovine tuberculosis (Mycobacterium bovis), [11,12] as well as a range of other viruses, bacteria and endo-and ectoparasites [13]. Transmission, and therefore the veterinary and medical significance, may be enhanced in the case of relatively high population densities [9].…”

Badgers and bTB infection

“…We are grateful to Georgina Mills ( VR , 15 December 2018, p 709), for her report on the paper by Barron and colleagues,1 pointing out the significant percentage (21 per cent) of badgers infected with bovine TB (bTB) in the edge area of Cheshire, and for the balanced reporting that infection transfer could be wildlife to cattle or cattle to wildlife.…”