West Nile virus season is here; mosquito experts offer tips for protection

By Denise Coffey - Staff Writer
Regional - posted Mon., Aug. 5, 2013

The Northeast District Department of Health issued a press release on July 30 regarding the discovery of mosquitoes that have tested positive for West Nile virus. A pool of mosquitoes sampled on July 24 from Cedar Swamp in Plainfield tested positive for the virus. The announcement that the virus season had started was expected, according to NDDH Health Director Susan Starkey.

“We started our West Nile virus messaging a few weeks ago,” Starkey said. “News of positive mosquito findings in Plainfield serves as a reminder for residents to take steps to protect themselves from mosquito bites now through September.”

Dr. Theodore Andreadis, chief medical entomologist with the state's Agricultural Experiment Station, said the discovery wasn't totally unanticipated. Most of the West Nile virus activity is concentrated along the Interstate 95 corridor in Fairfield and New Haven counties. “It typically runs from Greenwich to New Haven, with a fair amount of activity around the greater Hartford area,” Andreadis said. State tests have confirmed WNV in the area before, but it hasn't been common in the Plainfield area, he said.

Andreadis, who directs the state's mosquito trapping program, encouraged the public to take some precautions to prevent their exposure to the pests. “The fact that we picked it up in Plainfield is interesting,” he said. “What it means is that we do have some virus circulating in the area.”

The state traps mosquitoes at 91 locations every week. If a virus is detected, trapping frequencies increase to two to three times a week, so scientists can monitor the situation. The type of mosquito found to carry the virus was a species known as Culex restuans, a species known as a “bird biter,” said Andreadis. Populations of that species usually peak in July, and they occur in more rural environments. “It has a much higher tendency to feed on birds. It's not a species that feeds on humans to any great degree, so that reduces the risk,” he said.

Last year, the virus was found in 44 different communities throughout state, and 21 human cases were reported. The last time the West Nile virus was detected in Plainfield was 2004.

“It's important to understand West Nile virus is a viral disease that circulates in wild birds,” Andreadis said. “Mosquitoes pick it up by feeding on these birds. On occasion, some infected mosquitoes will feed on a human or horse to transmit it. If we have quite a bit of virus circulating in area, it gets picked up by a lot of other mosquitoes that have strong tendency to feed on humans. We're nowhere near any of that in the Plainfield area.” Calling the risk low to moderate, he suggested there was no reason to alter activities, apart from taking certain precautions.

Those precautions include spending a minimal amount of time outside between the hours of dusk and dawn, when mosquitoes are most active. Guidelines from NDDH suggest residents wear long-sleeved shirts, long pants, socks and shoes if outside for extended periods of time. Screens, doors and windows should be checked to make sure they secure tightly. Hikers and campers are urged to use insect repellent and mosquito netting if mosquito activity is intense. And Andreadis suggested people simply remove themselves from an area if there are too many mosquitoes. “There's no reason to call for any kind of pesticide spraying, but if the mosquito-biting frequency is intense, remove yourself from the area. If camping or hiking, use a repellant. That will greatly reduce the chances of being bitten by mosquitoes carrying West Nile,” he said.

State tests on July 10 and 17 found the eastern equine encephalitis virus in Voluntown. The back-to-back discoveries were a concern, according to Andreadis. But since those test dates, mosquito numbers have declined. “We haven't seen any further activity, but we are monitoring it closely,” he said.

For more information on West Nile virus and what you can do to prevent being bitten by mosquitoes, visit the Connecticut Mosquito Management Program website at www.ct.gov/mosquito.

Mosquito pools that test positive for West Nile virus and eastern equine encephalitis, as well as human cases of these illnesses, will also be posted on the Connecticut Mosquito Management Program website.

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