Eco-epidemiological Investigation of a Disease Outbreak among Pampas Foxes (Lycalopex gymnocercus) from a Protected Area in Southern Brazil.

Pathogens of domestic dogs have been reported in various carnivorans worldwide. Canine distemper virus (CDV) has been responsible for lethal outbreaks and population declines. Data are scarce regarding CDV outbreaks and their impact on South American canids. An eco-epidemiological investigation of a disease outbreak in a free-living population of Pampas foxes (Lycalopex gymnocercus) in a protected area (reserve) in southern Brazil began after locals informed our team of three foxes in the reserve showing signs of incoordination and seizures. Two carcasses of recently dead foxes were recovered and tested for CDV and rabies. Additionally, samples from 22 Pampas foxes live trapped in the study area were analyzed. Samples of the two dead foxes were positive for CDV antigen, and one of them for the presence of CDV RNA. None of the animals were positive for rabies virus. Analysis of a sequence from the CDV hemagglutinin gene allowed the classification of the CDV strain within the South America 1/Europe 1 (SA1/E1) clade, with high identity with other strains previously identified in domestic dogs. Approximately 90% of live-trapped Pampas foxes were seropositive for the presence of anti-CDV antibodies, and two of them showed myoclonus, indicating an outbreak of CDV in a population of free-ranging Pampas foxes in southern Brazil, possibly due to a spillover from domestic dogs.