EEE is a rare but serious disease caused by a virus. The virus infects birds that live in freshwater swamps and is spread from bird to bird by infected mosquitoes. If a mosquito infected with the virus bites a horse or human, the animal or person can become sick. The risk of getting EEE is highest from late July through September.
The first symptoms of EEE are high fever (103° - 106°F), stiff neck, headache, and lack of energy. These symptoms show up three to ten days after someone is bitten by an infected mosquito. Inflammation and swelling of the brain, called encephalitis, is the most dangerous symptom. The disease gets worse quickly and some patients may go into a coma within a week.
There is no cure for EEE, and three of every ten people who get the disease die from it. All doctors can do is lower the fever and ease the pressure on the brain. Some people who survive this disease will be permanently disabled. Few people recover completely.
The virus that causes EEE is spread only by mosquitoes.
EEE is very rare. Since it was first described in 1938 through 2005, 84 cases have been reported in Massachusetts. Fifty-one of the cases occurred during outbreaks in 1938-39 and 1955-56. Over half of the cases have been from Plymouth or Norfolk counties in southeastern Massachusetts. Rare cases have occurred outside of eastern Massachusetts.
Massachusetts developed a Surveillance and Response Plan the coordinates efforts of local officials and state agencies to reduce the risk of EEE. The plan involves checking for the virus in mosquitoes, reducing the number of mosquitoes in the environment, and educating people on the ways to avoid mosquito bites. Every year from May until the first hard frost, the Massachusetts Department of Public Health (MDPH) and local mosquito control projects collect mosquitoes from various locations around the state and send them to the State Laboratory for testing. If the virus that causes EEE is found in mosquitoes, MDPH will tell local boards of health and mosquito control projects and ask them to increase their education and mosquito control activities. MDPH provides educational materials for physicians, veterinarians, local public health officials, and the public along with updates on EEE activity in mosquitoes, horses and humans online.