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

Abstract

Summary1. 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 10Á3% and 17Á7% of the population. 3. Infection was aggregated in social groups in the west of the study area, con®rm-ing the ®ndings 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 signi®cant 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 signi®cant correlations were detected between the demographic characteristics of social groups and group infection status. 5. The distribution of disease re¯ects stable persistent foci of infection in the badger population, with limited evidence of transfer between social groups. The accurate identi®cation of stable foci of infection would allow a range of management strategies for the control of bovine TB to be eciently targeted in such populations. However, the extent to which this pattern of infection is representative of low-density and disturbed badger populations is unknown.

Bovine Tuberculosis in Cattle and Badgers in Localized Culling Areas

“…Although M. bovis infections are clustered in badgers, the edges of these clusters are not sharply defined (Delahay et al, 2000;Woodroffe et al, 2005c); so, even if every infected animal, or every member of an infected social group, could be identified and removed, it is likely that some animals immigrating into the cleared area would be infected, especially as infected badgers appear to disperse further than do uninfected animals (Pope et al, 2007). Imperfect detection of infection in badgers and imperfect badger removal elevate the chances of increased contact rates leading to increased transmission, constraining the ability of localized culling to reduce TB risks to cattle.…”

Is Mycobacterium bovis in the environment important for the persistence of bovine tuberculosis?

“…The biological integrity of these results is strengthened by identification of a direct relationship between latrine positivity and social group rate of excretion of M. bovis in faeces. The failure to detect excreting badgers in six of the social groups that showed evidence of environmental M. bovis may be due to the low sensitivity of culture, variation in the probability of capturing a badger while it is excreting (Delahay et al 2000), neighbouring excretors visiting these territories (Rogers et al 1997) and/or M. bovis persistence following prior contamination.…”

Cost-Benefit Analysis Model of Badger (Meles Meles) Culling to Reduce Cattle Herd Tuberculosis Breakdowns in Britain, With Particular Reference to Badger Perturbation

“…Where possible, all badger parameters were derived from a single study population (Woodchester Park, southwest England; see Rogers et al, 1997Rogers et al, , 1998Delahay et al, 2000;Wilkinson et al, 2000). Badgers were characterized by the following variables: social group, sex, age, and TB status.…”

“…However, the incidence of TB in cattle has continued to rise. Among the potential reasons why badger culling might not work (Delahay et al, 2003) is the proposition that the social perturbation of badger social groups after culling could increase the rate of TB spread (Swinton et al, 1997;Tuyttens et al, 2000). Analysis of the results of the Randomized Badger Culling Trial (RBCT) added further evidence of disease exacerbation in areas surrounding badger removal (Donnelly et al, 2003(Donnelly et al, , 2007.…”