The U.S. Department of Agriculture (USDA) Center for Epidemiology and
Animal Health, a part of USDA’s Animal and Plant Health Inspection
Service’s (APHIS) Veterinary Services program (VS), recently released its
outlook for the occurrence of West Nile virus (WNV) in equids during 2003.

The outlook discusses factors that influence the viral threat to equids and
resistance of the equids to the disease. Furthermore, it discusses two main
factors which influence the occurrence of WNV in a given population of
equids: the existence of mosquitos carrying the virus, and the presence of
susceptible equids in geographic proximity to mosquitos