Seroprevalence of maedi-visna infection in sheep in the north-east of Spain

Abstract A study was undertaken on the seroprevalence of maedi-visna infection, and its related pathology, in the North-East of Spain. The study included the provinces of Zaragoza (Saragossa), Huesca, Teruel, La Rioja and the south of Navarra (Navarre), and dealt mainly with Rasa, the main local breed of sheep. Two hundred and thirty-three randomly selected flocks, proportionally distributed in accordance with the total sheep population of each province, were studied. Each flock was visited and 20 randomly selected serum samples were taken. Pathological examinations were carried out on 43 live animals with obvious respiratory signs and/or cachexia. Two hundred and twenty-six (97%) flocks showed at least one seropositive animal, and 40.7% of the animals sampled were seropositive. There was little variation between provinces. Among the 43 animals subjected to pathological examination, 31 (72.1%) were seropositive, and typical lesions in the lungs and/or the mammary glands were detected in 24 of these animals. Lesions of sheep pulmonary adenomatosis (SPA) were observed in four sheep, all of them seropositive to maedi-visna virus.