A retrovirus of sheep and goats. A member of the lentivirus subfamily related to HIV.
First identified in Iceland when it was introduced by sheep imported from Germany and causes two diseases the most common, maedi, is a pulmonary infection (maedi is Icelandic for shortness of breath) and when it infects the nervous system, visna, a paralysis similar to multiple sclerosis (visna is Icelandic for wasting).
(18 Nov 1997)