Introduction.

The isolation of Mycobacterium avium paratuberculosis from rabbits (Oryctologus cuniculus) on farms in Scotland exposed a major gap in our understanding of the epidemiology of paratuberculosis by indicating that non-ruminant wild life pose a threat to domestic livestock which has important implications for the control of paratuberculosis. Here we determine the potential for other wild life to harbour M. a. paratuberculosis and to play a role in the epidemiology of paratuberculosis in farmed livestock.

Methods.

Carcasses of mammals and birds were collected on four farms where clinical cases of paratuberculosis were regularly encountered in farmed livestock and rabbits were known to be infected. Carcasses were subjected to gross examination, before tissues (primarily intestine and associated lymph nodes) were collected for microbiology and histopathology. Isolates of M. a. paratuberculosis were confirmed by demonstrating IS9000 by PCR.

Results.

Mycobacterium avium paratuberculosis was isolated from foxes (23/27), stoats (17/37), weasels (2/4), rats (3/35), wood mouse (3/88), hare (1/6), crow (36/60), rook (3/53) and jackdaw (1/38) and in the cases of foxes (12/26), stoats (1/13), weasels (2/4) and crows (1/60) was accompanied by lesions consistent with paratuberculosis. Significant numbers of bank voles, house mouse, feral and wood pigeons and house sparrow were sampled with negative results on culture.

Discussion.

Animals and birds, which either predate on rabbits or scavenge rabbit carcasses infected with M. a. paratuberculosis, are very likely to become infected with the organism. It is unlikely that the carnivores pose a threat to farmed livestock since their faeces are unlikely to be ingested by them. Bird faeces on the other hand could contaminate pasture and stored feedstuffs and be ingested by livestock on the home farm or adjacent premises. Based on the findings to date we consider rabbits to have the greatest potential for being involved in the epidemiology of paratuberculosis in farmed livestock.

SAC receives funding from Scottish Executive Environment and Rural Affairs Department.