EDITORIAL Wildlife

Mycobacterium bovis has an extremely wide host range, encompassing both domestic and wild mammals. There appears to be great variation between host species and even between individuals in susceptibility to infection. There is also variation in the speed of progression of the disease and, consequently, the risk of onward transmission. These inherent characteristics of the host response to M bovis infection make some mammal species more likely to maintain infection even in the complete absence of transmission from other hosts and, consequently, these species are termed ‘maintenance hosts’. In other mammal species – known as spillover hosts – infection will die out without constant reintroduction. This classification is not fixed, however, and mammalian species in different circumstances may be either maintenance or spillover hosts. In Great Britain, a survey of M bovis infection in wild mammals in south-west England showed that, while infection is found in a wide range of species, the prevalence in most species is low (Delahay and others 2007) suggesting that most are spillover hosts. Exceptions to this low prevalence are the European badger (Meles meles) (Bourne 2007) and deer, particularly fallow deer (Dama dama) (Delahay and others 2007). The European badger is considered a maintenance host for M bovis in much of western England, Wales, Northern Ireland and the Republic of Ireland and contributes to the persistence of tuberculosis (TB) in domestic mammals, particularly cattle, in those countries. The stalling of an M bovis eradication campaign in domestic animals can foretell the discovery of a wildlife maintenance host. Elsewhere in the world, wild mammalian maintenance hosts have been identified and are considered to contribute to disease in domestic animals. In mainland Europe, wild boar (Sus scrofa) and red deer (Cervus elaphus) in areas of France (Zanella and others 2008)