Environmental determinants of the Mycobacterium bovis concomitant infection in cattle and badgers in France

Landscape epidemiology analyses how environmental characteristics influence pathogen transmission between hosts of one or several species, by inducing constraints on space use by hosts, and/or on pathogen survival in the environment. Here, we analysed how environmental variables could be associated with the Mycobacterium bovis concomitant infection in both cattle and badgers, in an area of southwestern France. We defined circular spatial units (500 and 1000 m radiuses) centred on 113 setts of trapped badgers and including cattle pastures. The characteristics of spatial units where only one species had been found infected were compared with the ones where both cattle and badgers had been found infected. A multivariate logistic model was used to analyse the association between concomitant infection in both species and three groups of variables describing landscape, animal population and terrain features of spatial units. The terrain ruggedness index of pastures and the percentage of sand in their soil were positively associated with the odds of concomitant infection in cattle and badgers in the spatial units. The number of neighbouring badger groups was negatively associated with the odds of concomitant infection (spatial units of 1000 m radius), whereas the number of crop parcels was positively associated with the odds of concomitant infection (spatial units of 500 m radius). These results suggest that terrain features, badger population structure and food avail-abilitymay influence the spread of M. bovis infection between badgers and cattle, leading to concomitant infection of both species.