Mosquitoes with Eastern equine encephalitis found in Conn.

October 3, 2018

NEW HAVEN — For the first time this year in the state, mosquitoes have been found with Eastern equine encephalitis, a disease that, although rarely seen, has a 33 percent fatality rate in those who are hospitalized for symptoms.

The Connecticut Agricultural Experiment Station announced Wednesday that mosquitoes trapped in Hampton on September 19 and North Stonington on September 26 have tested positive for eastern equine encephalitis, or EEE. Both towns are east of the Connecticut River.

“Although mosquito populations are declining with the onset of cool weather, the late season detection of EEE virus and the continued detection of West Nile virus requires continued vigilance,” said Dr. Philip Armstrong, medical entomologist at CAES. “We will continue to monitor the situation and trap mosquitoes until the first killing frost.”

The experiment station announced in recent weeks that West Nile virus-infected mosquitoes were found in 53 towns and cities in the state. As yet there are no reported human or equine cases of EEE virus this season but there were 17 human cases of WNV infection reported in the state this year.

“Mosquitoes are still active, and EEE virus and West Nile virus continue to circulate in Connecticut,” said Dr. Theodore Andreadis, CAES director. “I encourage residents to take simple steps to prevent mosquito bites, such as using insect repellent and covering bare skin, especially during dusk and dawn when biting mosquitoes are most active.”

Eastern equine encephalitis is a rare but serious viral disease in people and horses. In addition to killing one thirst of those who develop serious symptoms, one-half of survivors suffer from permanent neurological damage. The disease causes inflammation of the brain.

The disease does not pass from horses to humans, according to the Centers for Disease Control.

“The EEE virus is maintained in a bird-mosquito transmission cycle involving primarily Culseta melanura mosquitoes,” Armstrong said. “This mosquito species feeds primarily on birds and is found in and around freshwater swamp habitats. It occasionally feeds on mammals and other mosquito species that feed opportunistically on both avian and mammalian hosts may transmit the virus from birds to humans.”

In Connecticut, outbreaks of EEE have occurred sporadically in horses since 1938 and the first locally-acquired human case and fatality was reported in the fall of 2013.

The EEE-infected mosquitoes were found by the state of Connecticut Mosquito Management Program, a collaborative effort involving the Department of Energy & Environmental Protection, the Connecticut Agricultural Experiment Station, the Department of Public Health, the Department of Agriculture, and the University of Connecticut Department of Pathobiology and Veterinary Science.


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