West Nile Virus In Connecticut: What Is To Be Done?

CONNECTICUT — The mosquitoes that bring the dreaded West Nile Virus to Connecticut each summer are back, and they're early.

Field teams from the Connecticut Agricultural Experiment Station trapped the season's first virus-positive bug in Milford on June 21.

Philip Armstrong, a virologist and medical entomologist in the Department of Environmental Sciences at the Center for Vector Biology & Zoonotic Diseases in CAES, said his colleagues usually don't come across WNV-bearing insects until early- to mid-July.

Armstrong said we have no more control over the mosquito infestations and subsequent WNV outbreaks than we do the weather.

West Nile virus has been detected in Connecticut every year since it was introduced into North America in 1999, when it "exceeded all our expectations," Armstrong said. "It re-emerges every summer, it's extremely dependable, and the levels of virus activity will fluctuate a lot from year to year, and that's really just depending on the summer weather."

If it's a hotter than average summer, the state is in for a heavy toll of WNV cases, Armstrong said. Last season, West Nile Virus was detected in 143 mosquito pools from 21 towns in Fairfield, Hartford and New Haven counties, with eight human cases. In 2019, CAES tracked WNV in 82 mosquito samples from 23 towns, and one human case was reported. The year before, 158 cases of West Nile virus were reported in Connecticut, of which four were fatal.

There are no vaccines to prevent or medications to treat WNV in people, according to the Centers for Disease Control and Prevention. Most people infected with the disease do not feel sick, but about one in five people who catch it develop a fever and other symptoms. About one out of 150 infected people develop a serious, sometimes fatal, illness.

"And the next few weeks and months of this kind of hot weather that we're experiencing right now is the perfect weather for West Nile virus and the mosquito that transmits it. It really likes hot, hot, hot weather," Armstrong said. "We're kind of holding our breath to see what happens."

Some municipalities can't wait, and have gone hardcore in their battle with the bugs. Those towns have begun treating storm drains, where the mosquitoes tend to breed, with larvicide to kill the young. Armstrong said the best technological solution would be to use a wide-area aerial larvicde, but that is impractical as the mosquitoes are infesting urban and suburban areas.

"There are not a lot of great options for mosquito control," the entomologist told Patch. "We fully expect it will continue to spread and amplify in the coming weeks and months ahead."

The mosquitoes' traditional stomping ground has been the communities along the Interstate 95 corridor, lower Fairfield County and lower New Haven County, from New Haven and Hartford down to Greenwich. Knowing what they know now, more teams from CAES are headed back to Milford to do additional trapping, according to Armstrong, but the bug hunt can be a bit of a crap shoot.

"It's kind of unpredictable exactly when and where it will resurface," he said.

What scientists do know is how to reduce the risk of WNV infection. CAES officials are advising residents to take the following steps to reduce the risk of being bitten by mosquitoes:

• Minimize time spent outdoors between dusk and dawn when mosquitoes are most active.
• Be sure door and window screens are tight-fitting and in good repair.
• Wear shoes, socks, long pants, and a long-sleeved shirt when outdoors for long periods of time, or when mosquitoes are more active. Clothing should be light colored and made of tightly woven materials that keep mosquitoes away from the skin.
• Use mosquito netting when sleeping outdoors or in an unscreened structure and to protect infants when outdoors.
• Consider the use of an EPA-approved mosquito repellent and apply according to directions when it is necessary to be outdoors.