Increasing numbers of mosquitoes carrying the West Nile virus have now spread to 14 cities and towns across Connecticut, state researchers reported Wednesday, although there has yet to be a case of reported human infection so far this year.
In addition, mosquitoes infected with Eastern equine encephalitis have been found in Voluntown and Madison, scientists with the Connecticut Agricultural Experiment Station said. No reported instances of humans with EEE have been reported this summer.
“Both viruses are expected to build up in the mosquito population in coming weeks and months ahead,” Philip Armstrong, medical entomologist at the experiment station, said.
The 14 Connecticut communities where mosquitoes carrying West Nile virus have been found include: Chester, East Haven, Greenwich, Groton, Hartford, Manchester, New Haven, North Haven, North Stonington, South Windsor, Stamford, Voluntown, West Haven and Wethersfield.
The first instance of mosquitoes carrying West Nile virus in Connecticut this year was reported on Aug. 1 and involved mosquitoes caught in East Haven.
“We are seeing increases in the number of mosquitoes carrying West Nile virus with expansion into new locations,” Armstrong said.
West Nile virus is the most common mosquito-borne disease in the U.S., with 2,647 reported human cases of infection and 167 deaths attributed to the virus, according to the federal Centers for Disease Control.
CDC reported there were 18 cases of mosquito-transmitted West Nile virus in Connecticut last year and one death as a result of such infection. Since 2000, there have been 157 human cases of West Nile virus reported in Connecticut and four deaths attributed to this disease.
Most people infected with West Nile virus don’t even feel sick, CDC experts say. About one of every five people who get the virus develop a fever and other symptoms, and about one in every 150 cases develop a serious illness that can result in death.
Eastern equine encephalitis is a much rarer and very dangerous mosquito-borne viral disease that can afflict both horses and humans.
Only about six cases of humans infected with EEE are reported each year in the U.S. Connecticut has seen sporadic instances of this disease in horses and domestic pheasants 1938. The first state case was reported in 2013 and resulted in the death of the infected person.
“The continued warm, humid weather enhances mosquito biting activity and heightens the risk of acquiring West Nile virus and Eastern equine encephalitis virus infection,” said the director of the Connecticut Agricultural Experiment Station, Theodore Andreadis.
Andreadis urged people going outdoors to use mosquito repellent and to cover their skin as much as possible during high-risk times of the day. The risk of getting bitten by mosquitoes is greatest at dawn and dusk when these blood-sucking insects are most active.
Experts say there are 52 different species of mosquitoes in Connecticut and less than half actually bite humans and livestock. Only 18 species of mosquitoes have been identified as carriers of West Nile virus and just five are considered prime carriers. It’s been estimated that, in areas where West Nile virus has been identified in mosquitoes, about one in 500 of the insects carry the disease.
Connecticut experiment station researchers operate a network of 92 mosquito-trapping stations in 72 cities and towns across the state. The trapping system starts up in June and runs into October.
Gregory B. Hladky can be contacted at ghladky@gmail.com
