Tuberculosis in badgers where the bovine tuberculosis epidemic is expanding in cattle in England

Swift, Benjamin Michael Connor; Sandoval Barron, Elsa; Christley, Rob; Corbetta, Davide; Grau-Roma, Llorenç; Jewell, Chris; O'cathail, Colman; Mitchell, Andy; Phoenix, Jess; Prosser, Alison; Rees, Catherine; Sorley, Marion; Verin, Ranieri; Bennett, Malcolm

Abstract

Bovine tuberculosis (bTB) is an important animal health and economic problem for the cattle industry and a potential zoonotic threat. Wild badgers (Meles meles) play a role on its epidemiology in some areas of high prevalence in cattle, particularly in the UK and Republic of Ireland and increasingly in parts of mainland Europe. However, little is known about the involvement of badgers in areas on the spatial edge of the cattle epidemic, where increasing prevalence in cattle is seen. Here we report the findings of a study of found-dead (mainly road-killed) badgers in six counties on the edge of the English epidemic of bTB in cattle. The overall prevalence of Mycobacterium tuberculosis complex (MTC) infection detected in the study area was 51/610 (8.3%, 95% CI 6.4-11%) with the county-level prevalence ranging from 15 to 4-5%. The MTC spoligotypes of recovered from badgers and cattle varied: in the northern part of the study area spoligotype SB0129 predominated in both cattle and badgers, but elsewhere there was a much wider range of spoligotypes found in badgers than in cattle, in which infection was mostly with the regional cattle spoligotype. The low prevalence of MTC in badgers in much of the study area, and, relative to in cattle, the lower density of sampling, make firm conclusions difficult to draw. However, with the exception of Cheshire (north-west of the study area), little evidence was found to link the expansion of the bTB epidemic in cattle in England to widespread badger infection. Bovine tuberculosis (bTB), primarily caused by Mycobacterium bovis, is an important animal health and economic problem for the British cattle industry, and an important zoonotic infection globally, particularly where bovine milk, the main source of human infection, is not treated 1. M. bovis, is a member of the M. tuberculosis complex (MTC) group of bacteria and predominantly infects cattle, but has a wide host range that includes badgers (Meles meles), other wildlife, camelids, goats, humans and some companion animals. Badgers are reported to act as one of the 'reservoirs' of M. bovis bacilli, at least in some areas 2-5. M. tuberculosis, the overwhelmingly most frequent cause of human TB and M. microti, which mainly circulates in field voles (Microtus agrestis) 6 , are also found in Great Britain. The incidence of TB in cattle in England and Wales has been rising since the mid-1980s, and the area in which it is considered endemic has gradually expanded to cover most of the south west of England and south Wales, the West Midlands and parts of mid-Wales 2. Although usually described as a single spreading epidemic, the regional distributions of different spoligotypes of M. bovis might suggest a series of regional epidemics 7. The government's strategy for achieving 'officially TB-free (OTF)' status for England is based on geographic areas of OPEN 1 The Royal Veterinary College, North Mymms, Hertfordshire AL9 7TA, UK.

Citation

Swift, B. M. C., Sandoval Barron, E., Christley, R., Corbetta, D., Grau-Roma, L., Jewell, C., …Bennett, M. (2021). Tuberculosis in badgers where the bovine tuberculosis epidemic is expanding in cattle in England. Scientific Reports, https://doi.org/10.1038/s41598-021-00473-6

• Journal Article Type: Article
• Acceptance Date: Sep 9, 2021
• Online Publication Date: Oct 25, 2021
• Publication Date: Oct 25, 2021
• Deposit Date: Nov 1, 2021
• Publicly Available Date: Nov 1, 2021
• Publisher: Nature Research
• Peer Reviewed: Peer Reviewed
• DOI: https://doi.org/10.1038/s41598-021-00473-6
• Public URL: https://rvc-repository.worktribe.com/output/1552055