Eastern equine encephalitis has been confirmed as the cause of death of three horses and believed to have caused the deaths of three other horses that have died in eastern Virginia during the past two weeks. According to the Associated Press, Dr. Bruce Akey of the Virginia Department of Agriculture said a viral encephalitis was confirmed by microscopic lesions found in the brains of three of the animals. Akey said further tests are being done on the three other horses, with tissue samples from all six sent to the U.S. Department of Agriculture's national laboratory in Ames, Iowa.Three of the horse deaths occurred in Suffolk and three in Chesapeake, both of which are in the Hampton Roads region of the state.Veterinarian Brandon Wichman had treated one of the animals in Suffolk before learning that other horses in the area had shown similar symptoms of lethargy, loss of muscle control in the eyes and on the face, and abnormal leg motion and control, the AP reported. Noting there are one or two cases of the disease in eastern Virginia each year, Wichman said, "It's a pretty scary thing. I've never heard of this many cases in such a short time frame."The disease is spread by mosquitoes that feed on birds and small rodents and then carry it to horses and humans, according to the press service. Akey said horse, humans, and large birds are susceptible to the disease, while dogs, cats, and farm animals such as cows, pigs, sheep, and goats are not. Horses can be vaccinated to prevent the virus, but there is no vaccine against the disease for humans.