CURRENT CONCEPTS IN THE EPIZOOTIOLOGY, DIAGNOSIS, AND ECONOMIC IMPORTANCE OF OVINE PROGRESSIVE PNEUMONIA IN NORTH-AMERICA - A REVIEW

Lentiviruses, a genus of retroviruses, include the agents that cause o vine progressive pneumonia or maedi. Infection is characterized by lon g incubation periods and insidious, slowly progressive clinical course s resulting in chronic degenerative diseases. The ovine lentiviruses a re widespread among sheep in North America, yet their significance to livestock production is currently not well defined. Lentiviruses persi st and replicate in the presence of host specific immune responses and cause immune-mediated lesions in several organ systems. Due to this u nusual relationship with their host, the diagnosis, control and treatm ent of these infections is difficult and expensive. Scientific studies on the biology of ovine lentiviruses (OvLV) and their complex relatio nship with the host are yielding new approaches to the detection of in fected animals and methods for study of the epizootiology and control of OvLV-related diseases, We summarize some of the known biological pr operties of the virus, spectrum of clinical features of the diseases, current concepts of disease pathogenesis, economic importance, and str ategies used to diagnose and control OvLV infections. (C) 1998 Elsevie r Science B.V.