High prevalence of visna in sheep in north-west Spain.

The article reports on the high prevalence of maedi-visna disease, the nervous form of the viral disease in sheep in Spain. A study conducted confirmed the virus infection in sheep using techniques like immunohistochemistry, enzyme-linked immunosorbent assay and polymerase chain reaction. The possible reasons for the high number of cases of visna are neutrotopic strains of the virus, breed susceptibility and farming practices.