Eastern equine encephalitis virus (EEE), commonly called sleeping sickness (not to be confused with Trypanosomiasis) or Triple E, is a zoonotic alphavirus and arbovirus present in North, Central and South America and the Caribbean. EEE was first recognized in Massachusetts, USA in 1831 when 75 horses died of encephalitic illness.
There is no specific therapy for EEE. Once signs of disease are present, passive antibody transfusion has no beneficial effect. The treatment is symptomatic and is restricted to maintaining vital functions.
The agent of EEE is a member of the family Togaviridae, genus Alphavirus. A varient of EEE virus exists in Central America and parts of South America. It can be differentiated serologically and seems to be less harmful. 9
While EEE cases are rare, the fatality rate in humans is about 35%, the highest among arboviruses transmitted in the U.S. Approximately 35% of patients who recover suffer some degree of brain damage and may require permanent institutional care. EEE virus also can cause severe disease and death in horses.
The cause of Eastern Equine Encephalitis (EEE) was first identified in the 1930s. From 1964 to 1995, 151 cases were reported in the U.S., with an average of about five cases per year. A few cases of EEE have been diagnosed in Indiana, all in the northern tier of counties in association with swamps.
According to the Centers for Disease Control and Prevention, eastern equine encephalitis is a rare illness in humans. Most persons infected with it have no apparent illness. Severe cases begin with the sudden onset of headache, high fever, chills and vomiting.
The EEE virus is maintained in nature through a cycle involving the freshwater swamp mosquito Culiseta melanura, commonly known as the blacktailed mosquito. Two to three days after becoming infected with EEE virus, a mosquito becomes capable of transmitting the virus. Infected mosquitoes that feed on both birds and mammals can transmit the disease to horses and humans.
There is no cure for eastern equine encephalitis. However, supportive care is recommended to lower fever and ease pressure on the brain.
The first signs of Eastern equine encephalitis may include high fever (103°-106°F), stiff neck, headache, lack of energy, and inflammation of the brain. The disease gets worse quickly and some patients may go into a coma within a week.
[The mosquito Culiseta melanura] does not feed on humans or horses, but in rare cases the virus can escape from its marsh habitat in other mosquitoes that feed on both birds and mammals (including horses and humans) and then transmit the virus to mammals, including people. Horses and humans are "dead end" hosts, meaning that they do not develop enough virus in their blood to transmit the virus (therefore sick horses or humans can't transmit the disease to mosquitoes, only birds can).
Eastern equine encephalitis (EEE) is a virus disease transmitted to horses and humans by mosquitoes. Birds are the source of infection for mosquitoes. The virus is found along the east coast from New England to Florida, the Gulf Coast, and some midwestern areas. The principal vector in avian populations is the mosquito Culiseta melanura.