Spatial association of Mycobacterium bovis infection in cattle and badgers Meles meles

Abstract

Summary 1.Control of zoonotic disease is difficult to achieve when populations of multiple hosts, particularly wildlife, become persistently infected. Bovine tuberculosis (TB) is one such disease: its causative agent, Mycobacterium bovis , infects cattle, humans and multiple wildlife species including European badgers Meles meles . 2. In Britain, from 1974 to 1998 various strategies for the control of cattle TB involved culling badgers in the immediate vicinity of TB-affected herds. However, patterns of association between cattle and badgers had not been investigated at a local scale. 3. Using data from the Randomized Badger Culling Trial, an ongoing large-scale study of TB dynamics and control, we investigated local geographical associations between M. bovis infection in badgers and cattle. 4. Mycobacterium bovis infections were locally clustered within both badger and cattle populations. 5. We show, for the first time, that M. bovis infections in badgers and cattle are spatially associated at a scale of 1-2 km. Badgers and cattle infected with the same strain type of M. bovis are particularly closely correlated. These observational data support the hypothesis that transmission occurs between the two host species; however, they cannot be used to evaluate the relative importance of badger-to-cattle and cattle-tobadger transmission. 6. Synthesis and applications . The close associations between M. bovis infections in cattle and badgers suggest that localized badger culling could reasonably be expected to reduce the risks of cattle TB infection; however, experimental culls have found no such beneficial effects over the time-scale on which they were tested. This demonstrates the difficulty of predicting the outcome of management interventions, and reinforces the need for well-designed empirical assessments of future control strategies.

Culling and cattle controls influence tuberculosis risk for badgers

“…Analyses of data on cubs are in the supporting information. We constructed a base model including three covariates considered likely to influence the probability of detecting infection (whether the carcass was stored Ͼ7 days, necropsy laboratory, and culture laboratory): one to represent geographical variation (trial area) and two previously found to influence prevalence (gender and tooth wear) (10).…”

“…However, even though patterns of M. bovis infection in cattle and badgers are associated in space (10), distinguishing badger-to-cattle transmission of infection, which has been demonstrated experimentally (3,4,11), from cattle-to-badger transmission is problematic in observational studies, especially where badgers are being sampled destructively. While the RBCT was in progress, measures to control a nationwide epidemic of foot-and-mouth disease (FMD) led to a 9-month suspension of routine cattle TB testing (12).…”

Spatial clustering of TB-infected cattle herds prior to and following proactive badger removal

“…generalized linear geostatistical models (GLGMs) [5, chapter 4] to analyse the data. To date, spatial association of infection in cattle has been mainly studied using nearest neighbour methods [6][7][8][9][10]. However, unlike GLGMs, these methods do not allow for spatial variation in population density, do not take covariates into account, or do not establish the range of clustering.…”

Who infects whom? Social networks and tuberculosis transmission in wild meerkats

“…The social structure of animal populations significantly influences the transmission dynamics and persistence of infectious diseases (Altizer et al 2003;Perkins et al 2008;Woodroffe et al 2009). Knowledge of host interaction patterns is critical if we are to understand infectious disease transmission within a population (Cross et al 2005).…”