The cerebrospinal fluid in visna, a slow viral disease of sheep.

The temporal development of the CSF abnormalities was examined in visna, a chronic neurological disease caused by a persistent viral infection of sheep. Two types of changes were observed. During the first 30 to 40 days there was an intense mononuclear pleocytosis associated with high protein and proportionately elevated IgG. Later, there was a persistent slight pleocytosis associated with mildly elevated protein which had an increased proportion of IgG and antivisna antibody. These later cellular and protein changes are similar to those found in a number of chronic neurological diseases of man.