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Travel health information for people travelling abroad from the UK

Eastern Equine Encephalitis


Eastern Equine Encephalitis (EEE) is a viral infection, transmitted to humans by the bite of an infected mosquito. It is most commonly found swampy areas of the eastern, Gulf and north central United States (US).

The Illness

The virus can cause disease in humans, horses and birds.Most infections in humans cause no symptoms and severe brain infection is rare; (on average 6 cases each year in the US) 4-10 days after infection, a high fever develops followed followed by headache coma and convulsions. The severe infection is fatal in 35% of cases.


There is no specific treatment for EEE. Patients will often require hospitalisation and intensive care support to assist with breathing and circulatory problems.

Recommendations for Travellers

Travellers at highest risk are visitors to swampy areas of the Eastern Gulf states of the US who endemic are engaging in outdoor work or recreational activity.

Travellers to areas of risk should practice mosquito bite avoidance.

No human vaccine against EEE virus is available.

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