Maedi-Visna virus infection in a Merino lamb with nervous signs

A Maedi-Visna virus (MVV) infection was diagnosed in a 10-month-old lamb from a Turkish flock. The animal suddenly showed nervous signs and died within 2 days. At necropsy, different pulmonary and nervous lesions were observed. A Coenurus cerebralis cyst was also present in the right-brain hemisphere. Severe nonpurulent meningoencephalitis and lymphoproliferative pneumonia were detected by histopathology. MVV proviral DNA was demonstrated by polymerase chain reaction (PCR) in formalin-fixed and paraffin-embedded samples collected from the brain and the lungs. This unusual report in a young animal confirms that not only adult sheep but also lambs can develop MVV disease. The hypothesis that concurrent nervous and pulmonary diseases increase the severity of the lesions due to MVV and reduce the incubation time should be better evaluated.