Western Equine Encephalitis

Western equine encephalitis is a viral disease that is spread by infected mosquitoes to horses and humans. One of several mosquito-borne viral illnesses, it is found mainly in the plains regions of the western and central United States. Major complications, including brain damage, are reported in about 13 percent of infected people overall and in about a third of infants diagnosed with the disease. Since 1964, 639 human cases of western equine encephalitis have been confirmed in the United States.

 

What Is Western Equine Encephalitis?

Western equine encephalitis is a disease that is spread to horses and humans by infected mosquitoes.
 
Western equine encephalitis 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 found mainly in the plains regions of the western and central United States.
 
While there is no specific treatment for western equine encephalitis, prevention involves controlling mosquitoes and avoiding mosquito bites.
 

What Causes Western Equine Encephalitis?

Western equine encephalitis is caused by the western equine encephalitis virus, an arbovirus. Arbovirus is short for arthropod-borne 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.
 
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Written by/reviewed by: Arthur Schoenstadt, MD
Last reviewed by: Arthur Schoenstadt, MD