Severe outbreak of disease in the southern chamois (Rupicapra pyrenaica) associated with border disease virus infection

An outbreak of a previously unreported disease affecting southern chamois (Rupicapra pyrenaica) in the central Pyrenees (NE Spain) was recorded in 2001 and 2002. There was a marked temporal distribution, most animals being found between February and June. After the outbreak, the population was found to have decreased by about 42%, most probably due to the disease. We examined 20 affected chamois. Clinical manifestations included depression, weakness and movement difficulties in all cases. Three chamois presented abnormal behaviour, with absence of flight reaction, and 16 showed different degrees of alopecia with skin hyperpigmentation. At necropsy cachexia was observed in all animals, four chamois had abscesses in different parts of the body, four had pneumonia, one had an extensive subcutaneous infection on the head and neck and one had severe orchitis. Microscopic lesions were found in the brain, mainly edema, gliosis, espongiosis, cariorrexis and neuronal multifocal necrosis. A perivascular mononuclear inflammatory infiltrate was present in three of them. Skin lesions included marked follicular atrophy, mild to moderate epidermal hyperplasia with orthokeratotic hyperkeratosis and follicular hyperkeratosis, and hypermelanosis. In 13 chamois there were haemosiderin deposits in the spleen, and in three individuals kidney “cloissone” was observed. Intraeritrocitic parasites were detected either by direct observation or PCR in 8 of 17 chamois. A pestivirus was isolated and detected by RT-PCR from 12 of 13 affected chamois and antigenic characterized as border disease virus by monoclonal antibodies. This is the first time a border disease virus has been associated with an outbreak of a high-mortality disease in a wild species.