The spatio-temporal distribution of Mycobacterium boris (bovine tuberculosis) infection in a high-density badger population

Abstract

1. The European badger (Meles meles) is implicated as a reservoir of Mycobacterium bovis (bovine TB) infection for cattle in Britain and Ireland. In the present study the spatio-temporal distribution of M. bovis infection was investigated. Analyses were carried out on data from a long-term epidemiological and ecological study of the dynamics of bovine TB in a wild population of badgers at Woodchester Park in south-west England. 2. During the 15 years of the capture-mark-recapture study (1982-96), 3316 trapping and post-mortem records were obtained from 1270 individual badgers. Annual prevalence of infection based on positive serological and bacterial tests varies between 10.3% and 17.7% of the population. 3. Infection was aggregated in social groups in the west of the study area, confirming the findings of previous studies. However, temporal trends in disease were not synchronized amongst neighbouring groups, suggesting low rates of disease transfer between them. 4. There was significant serial correlation in the disease status within groups over time, suggesting that infection persists for many years in some social groups. The presence of infectious adult female badgers in groups was associated with new infections, and provides further evidence for their importance in the maintenance of infection within groups. However, no statistically significant correlations were detected between the demographic characteristics of social groups and group infection status. 5. The distribution of disease reflects stable persistent loci of infection in the badger population, with limited evidence of transfer between social groups. The accurate identification of stable foci of infection would allow a range of management strategies for the control of bovine TB to be efficiently targeted in such populations. However, the extent to which this pattern of infection is representative of low-density and disturbed badger populations is unknown.