|Knowles Jr, Donald|
Submitted to: Vedalia
Publication Type: Book / Chapter
Publication Acceptance Date: 5/1/1997
Publication Date: N/A
Interpretive Summary: The Office International Epizootics Manual of Standards is for worldwide distribution and describes the current methods of diagnosing and vaccinating against infectious disease of international importance. The above chapter reviews the diagnosis of the sheep lentivirus (ovine progressive pneumonia virus) and the goat lentivirus (caprine arthritis-encephalitis virus). Vaccines aren't available for either disease. Infection with both viruses is most economically achieved through serology. The most cost effective and accurate serologic test currently available is the agar gel immunodiffusion test. The user must assure that the appropriate antigen preparation is used when performing the AGID.
Technical Abstract: Maedi-visna (MV), or ovine progressive pneumonia (OPP), of sheep and caprine arthritis-encephalitis (CAE) of goats are persistent virus infections caused by closely related lentiviruses. The primary route of transmission of MV/OPP virus to lambs or CAE virus to kids is via colostrum or milk during nursing. Ovine lentiviruses have been identified in most of the sheep rearing countries of the world, with the notable exceptions of Australia and New Zealand. The distribution of CAE virus is highest in industrialized countries and seems to have coincided with the international movement of European breeds of dairy goats. Clinical and subclinical MV and CAE are associated with progressive, mononuclear cell inflammatory lesions in the lungs, joints, udder and central nervous system. In both species indurative mastitis is common and its economic significance may be underestimated. Labored breathing associated with emaciation caused by progressive pneumonitis are the predominant features in clinically affected sheep, whereas polyarthritis is the main disease in goats. However, most lentivurus-infected sheep and goats are largely asymptomatic, but remain persistent carriers of virus and are capable of transmitting infection via colostrum or milk and respiratory secretions. The most practical and reliable approach to confirming a diagnosis of MV or CAE is a combination of serology and clinical evaluation. Although serology represents the most cost-effective method of diagnosing persistently infected clinically normal animals, it should be understood that testing errors occur.