Eastern Equine Encephalitis Virus

The disease Eastern Equine Encephalitis (EEE) has caused more than three deaths in the United States of America. The Department of Health has issued advisories to the people.

What is Eastern Equine Encephalitis?

Eastern Equine Encephalitis caused by EEE virus is a rare cause of brain infections (encephalitis).

The EEE virus infection can result in one of two types of illness, systemic or encephalitic depending on the age of the person and other host factors. No cure has been found to the disease yet. Approximately a third of all people with EEE die from the disease.

Of those who recover, many are left with disabling and progressive mental and physical sequelae, which can range from minimal brain dysfunction to severe intellectual impairment, personality disorders, seizures, paralysis, and cranial nerve dysfunction.

Transmission of the Virus

EEE Virus is capable of infecting a wide range of animals, including mammals, birds, reptiles, and amphibians. The virus is sustained  in the environment through a bird—mosquito cycle.

Two mosquito species i.e. Culiseta melanura and Cs. morsitans are primarily involved in this portion of the cycle. These mosquitoes feed on the blood of birds. The frequency of the virus found in nature increases throughout the summer as more birds and more mosquitoes become infected.

Transmission to humans and other mammals occurs via other mosquito species, which feed on the blood of both birds and mammals. These mosquitoes are referred to as “bridge vectors” as they carry the virus from the avian hosts to other types of hosts, particularly mammals.