Prevention strategies against small ruminant lentiviruses: an update.

Small ruminant lentiviruses (SRLVs), including maedi-visna virus (MVV) of sheep and caprine arthritis-encephalitis virus (CAEV), are widespread, cause fatal diseases and are responsible for major production losses in sheep and goats. Seventy years after the legendary maedi-visna sheep epidemic in Iceland, which led to the first isolation of a SRLV and subsequent eradication of the infection, no vaccine or treatment against infection has been fully successful. Research during the last two decades has produced sensitive diagnostic tools, leading to a variety of approaches to control infection. The underlying difficulty is to select the strategies applicable to different epidemiological conditions. This review updates the knowledge on diagnosis, risk of infection, immunisation approaches and criteria for selecting the different strategies to control the spread of SRLVs.