Eastern Equine Encephalitis virus (EEEV), a member of the togavirus family, has garnered recent media attention as several sentinel chickens have tested positive for this virus in Orange County, Florida over the last few weeks.  While chickens cannot directly transmit the virus, infected mosquitos can transmit the virus to humans.

Sentinel chickens are fowl that are regularly tested for the disease. Chickens do not display signs and symptoms of EEE.  The presence of EEE in sentinel chickens has raised concern for an increased risk for human transmission.  The number of cases are relatively infrequent, with an average 7 cases/year being reported in the United States since 2009.  The state with the largest number of total cases since 2009 has been Florida, with a total case count of 13.  Cases most often occur in swampy areas and the very young and elderly are at greatest risk of infection.

The incubation period for the virus is 5-10 days after which symptoms develop suddenly and may include altered mental status, fever, chills, and vomiting. Symptoms may progress to seizures and coma.  The mortality of EEE is 30–75% and the incidence of severe neurologic sequelae in survivors is high.

No antiviral therapy currently exists for humans. No vaccine is available.  Treatment is considered supportive. Prevention of mosquito bites is the only method to avoid infection from EEE. Effective mosquito prevention entails using insect repellent using an EPA approved active ingredient, wearing long-sleeved clothing, and treating clothing and gear with appropriate insect repellent. 

Read more:

CDC: Eastern Equine Encephalitis Home

Harrison's Principles of Internal Medicine, 20e: Chapter 204: Arthropod-Borne and Rodent-Borne Virus Infections