Mosquitoes that feed on EEE-infected birds can transmit the virus to humans, horses, and other birds. | Photo: iStock

Case number 11, a yearling filly from Burlington County with unknown vaccination status, was euthanized. Case number 12 is a 3-year-old Camden County gelding reported as having been vaccinated. His status was not reported.

EEE 101

Eastern equine encephalomyelitis is caused by the Eastern equine encephalitis virus, for which wild birds are a natural reservoir. Mosquitoes that feed on EEE-infected birds can transmit the virus to humans, horses, and other birds. Horses do not develop high enough levels of these viruses in their blood to be contagious to other animals or humans. Because of the high mortality rate in horses and humans, EEE is regarded as one of the most serious mosquito-borne diseases in the United States