All mosquitoes collected in state will also be tested for West Nile virus, EEE virus

The State of Connecticut Mosquito Management Program (MMP) announced that the seasonal mosquito trapping and testing program coordinated by the Connecticut Agricultural Experiment Station (CAES) will begin today, May 31st. The program monitors the types, numbers and locations of mosquitoes and tests them for the presence of viruses that can cause illness including West Nile virus (WNV) and Eastern Equine Encephalitis virus (EEE). In addition, mosquitoes will be tested for Zika virus. First test results will be available during the week of June 6. 

"With regard to Zika virus, our overriding goal will be to prevent the establishment of the virus in the State, in the unlikely event that we detect Zika in local mosquito populations," said Dr. Theodore Andreadis, Director, The Connecticut Agricultural Experiment Station.

"It is important to remember that currently the threat of Zika virus infections among Connecticut residents is the result of travel to Zika-affected areas and sexual transmission from infected men to their partners," said Dr. Raul Pino, Commissioner, Department of Public Health. "While we do not at this time anticipate much local mosquito transmission of Zika this season, we will be vigilantly monitoring our local mosquito populations and working with our municipal partners to engage communities and citizens in taking common sense steps to help reduce mosquito populations."

WNV Surveillance

Last season, CAES trapped and tested nearly 180,000 mosquitoes and identified WNV-positive mosquitoes collected at trap sites in 24 towns in 6 counties (Fairfield, Hartford, Middlesex, New Haven, New London, and Windham). The majority of WNV activity was detected in mosquitoes collected from towns in southwestern Connecticut.

During 2015, 10 persons were reported with WNV-associated illnesses; they were residents of: Bridgeport (6), Fairfield (1), Milford (1), New Haven (1), and Shelton (1). Clinical syndromes were classified according to the national surveillance case definition and included encephalitis (5), meningitis (3) and WN fever (2). Median age of the patients was 64.5 years (range = 35-90 years) with onset of symptoms from August 9 to October 9. While there were no fatalities, patients with meningitis or encephalitis may suffer lasting symptoms resulting from neurological damage.

EEE Surveillance

EEE is a rare illness in humans, and only a few cases are reported in the United States each year, mostly in the Atlantic and Gulf Coast states. However, it often causes serious neurologic illnesses and fatalities. During 2015, no EEE infected mosquitoes were identified and no human or domestic animal infections were reported in Connecticut.

Zika Surveillance

Zika virus was recently introduced into the Western Hemisphere and is spreading in tropical regions of Latin America and the Caribbean Islands. Zika commonly causes fever, rash, conjunctivitis or other mild symptoms and rarely a neurological illness (Guillain-Barré syndrome) among infected people. It can also cause serious birth defects when a woman is infected during pregnancy.

The yellow fever mosquito (Aedes aegypti) is the primary mosquito species involved in the Latin American epidemic and does not occur in Connecticut. Another mosquito species, the Asian tiger mosquito (Aedes albopictus), may also transmit Zika virus. The Asian tiger mosquito has a more temperate distribution in the U.S. and has been identified in lower Fairfield and New Haven counties. The CAES will be monitoring the distribution and abundance of Aedes albopictus within the state and all mosquitoes collected will be screened for the presence of Zika virus in addition to WNV and EEE.

Connecticut Mosquito Management Program

The response to mosquito transmitted diseases in Connecticut is a collaborative inter-agency effort involving the Department of Energy and Environmental Protection (DEEP), the Connecticut Agricultural Experiment Station (CAES), the Department of Public Health (DPH), the Department of Agriculture and the Department of Pathobiology at the University of Connecticut (UCONN). These agencies are responsible for monitoring mosquito populations and the potential public health threat of mosquito-borne diseases. The CAES maintains a network of 91 mosquito-trapping stations in 72 municipalities throughout the state. Mosquito trapping and testing begins in June and continues into October.

For more information on WNV and EEE, what can be done to prevent getting bitten by mosquitoes, and the latest mosquito test results and human infections, visit the Connecticut Mosquito Management Program web site at For more information on Zika virus, please visit