June 24, 2022: The Centers for Disease Control and Prevention has listed Fairfield, Hartford, New London, Middlesex, Tolland, and Windham Counties in Low/Green the as part of its COVID-19 Community Levels Map. Only Litchfield, Middlesex and New Haven County are listed in the Medium/Yellow category. Residents who live in the Medium /Yellow counties who are at a high risk for severe illness, should talk to their health care provider about whether to wear a mask and take other precautions. These residents should stay up to date with their COVID-19 vaccines and get tested if they have symptoms. Visit the CDC COVID-19 Community Levels Map for updates.

Eastern Equine Encephalitis

Culiseta melanura


Eastern Equine encephalitis virus (EEEV) is spread to people through the bite of infected mosquitoes. EEEV is rare in the United States with an average of 7 cases reported each year. The virus is found in mosquitoes in Connecticut. There is no vaccine to prevent or medicine to treat EEEV infection. Approximately one third of people who become sick from EEEV will die from the illness. Early recognition and prompt supportive treatment can lower the risk of complications and death. The best way to prevent getting sick from EEEV is to prevent mosquito bites.


About Eastern Equine Encephalitis

Where in the United States, Has EEEV Been Found?

ArboNET National Data


Connecticut's EEE Response Plan for 2020


Information for Clinicians

Clinical Evaluation

National Surveillance Case Definition


Connecticut Provider Reporting Information

Reportable Disease Confidential Case Report form, PD-23

Connecticut Laboratory Reporting Information

Reportable Laboratory Findings form, OL-15C


EEEV testing at the State Public Health Laboratory


State Public Health Laboratory Contacts – for additional information


Connecticut EEEV Surveillance

In 2000, encephalitis was added to the state-wide reportable disease list, which included Eastern Equine encephalitis (EEE). During 2003-2018, there was one case of EEE reported to the Connecticut Department of Public Health. Mosquitoes that can spread EEE are found in Connecticut.

Connecticut Annual Infectious Diseases Statistics

Connecticut Agricultural Experiment Station

The Connecticut Agricultural Experiment Station conducts mosquito trapping and tests for viruses including EEEV during June to October each year.


Mosquito Trapping and Arbovirus Testing Program

Current Mosquito Testing Results

Past-Years Summaries of Mosquito Testing Results

Identification Guide to the Mosquitoes of Connecticut  

Vector-borne Disease Symposium- Symposium of Mosquito-Borne Disease in Connecticut, held on April 11, 2019.

Additional Resources


Connecticut Mosquito Management Program

Workplace Safety - Mosquito-Borne Diseases   NIOSH




Page last updated 8/11/2020.