Prevention centers on controlling mosquitoes and avoiding mosquito bites. Western equine encephalitis is a disease that is spread to horses and humans by infected mosquitoes. It is one of a group of mosquito-borne virus diseases that can affect the central nervous system and cause severe complications and even death. Other similar diseases are eastern equine encephalitis, St. Louis encephalitis, and LaCrosse encephalitis. Western equine encephalitis is caused by the western equine encephalitis virus, an arbovirus.
Arbovirus is short for ar thropod- bo rne virus .
Arboviruses are a large group of viruses that are spread by certain invertebrate animals, mainly blood-sucking insects. In the United States, arboviruses are usually spread by infected mosquitoes. Birds are often the source of infection for mosquitoes, which can sometimes spread the infection to horses, other animals, and, in rare cases, people. Western equine encephalitis is found in North, Central, and South America, but most cases have been reported from the plains regions of the western and central United States. The virus that causes western equine encephalitis has a complex life cycle involving birds and a specific type of mosquito, Culex tarsalis , that is common in farming areas and around irrigated fields.