Eastern equin entis e Western equin entis we and Venezuelan equin entis ve are caused by Alpha viruses birds and rodents are the primary reservoirs but unvaccinated horses are susceptible and these diseases are infectious to humans Eastern equin entis is most common and found in the United States especially in areas of high biting mosquito populations infection causes non-specific clinical signs affecting the central nervous system these signs include fever severe depression sleeping sickness Behavior changes impaired Vision circling or head pressing muscle twitches inability to swallow paralysis and convulsions death with survival rates for horses infected with e or ve is low however we survival can be as high as 70 to 80% where a vaccine is available