Contact rates between wild and domestic canids: no evidence of parvovirus or canine distemper virus in crab-eating foxes

Evaluating the risk of disease spill-over from domestic dogs to wildlife de pends on knowledge of inter-specific contact rates and/or exposure to aetio logical agents in dog environments. Here, contact rates of crab-eating foxe s (Cerdocyon thous) with sympatric domestic dog populations were measured o ver 25 months in Amazon Brazil. Foxes and dogs were serologically and clini cally monitored for exposure to canine parvovirus (CPV-2) and canine distem per virus (CDV), pathogens known to have caused wildlife population decline s elsewhere. Twenty-two of 24 (92%) tagged foxes visited one or more houses in a median 2 (range 1-3) villages per night where dog densities ranged fr om 7.2 to 15.4 per km(2) (mean 9.5 per km(2)). Foxes spent an average 6.4% (0-40.3%) of their 10 h nocturnal activity period in villages, the equivale nt of 38 m (range 0-242) per night. The rate of potential exposure to disea se agents was thus high, though varied by 3 orders of magnitude for individ ual foxes. Overall, 46% of the fox population was responsible for 80% of al l contacts. None of the 37 monitored foxes however showed serological or cl inical evidence of infection with CPV-2 or CDV. Seroprevalences for CPV-2 a nd CDV antibodies in the local domestic dog population were 13% (3/23) and 9% (2/23), respectively. and 89% of 97 monitored pups born during the study presented clinical signs consistent with active CPV-2 infection (haemorrha gic diarrhoea, vomiting, rapid morbidity and emaciation). Although there wa s no evidence for infection with either virus in foxes, the high level of c ontact of foxes with peridomestic habitats suggests that the probability of potential spill-over infections from dogs to foxes is high. (C) 2001 Elsev ier Science B.V. All rights reserved.