Mosquitoes In Greenwich Test Positive For West Nile Virus: State

GREENWICH, CT — A couple of mosquitoes in Greenwich have tested positive for West Nile Virus (WNV).

The Connecticut Agricultural Experiment Station (CAES), which is responsible for trapping, identifying, and testing mosquitoes for encephalitis viruses statewide, noted in their latest results posted this week that two mosquitoes out of the 819 collected and tested near the Cohen Eastern Greenwich Civic Center site were positive for WNV.

The Greenwich Department of Health noted in a news release two types of mosquitoes were trapped: Culex pipiens and Culex restuans. Culex pipiens are generally bird and mammal biting which breed in standing water often found in artificial containers like discarded tires, birdbaths and catch basins.

Culex restuans feed primarily on birds but are reported to bite humans when abundant. They breed in artificial containers, like catch basins, woodland and temporary pools, and are tolerant of polluted waters, the town said.

These are the first mosquitoes positive for WNV in Greenwich this year. WNV-positive mosquito pools have also been found in Branford Bridgeport, Darien, East Haddam, East Haven, Fairfield, New Canaan, Norwalk, South Windsor, Stamford, Wallingford and Wethersfield.

There have been zero human cases of WNV in Connecticut so far this year. In 2022, two CT residents developed WNV-associated illnesses. The cases were not fatal.

The Greenwich Health Department said it is continuing its preemptive larviciding program, which includes the treatment of public and private roadway catch basins, public school ground catch basins and other property owned and operated by the town, as needed. The larviciding program began in June and is reapplied every four to six weeks.

"Controlling the mosquito population in the larval stage through the application of larvicide has been found to be a prudent action; however, this measure only helps to reduce the mosquito population, not eliminate it," said Greenwich Director of Health Caroline Calderone Baisley. "The recent warm weather and periodic rain events have increased the ability for mosquitoes to breed. Residents are encouraged to protect themselves whenever they are outdoors."

The Centers for Disease Control and Prevention says on its website that WNV is the leading cause of mosquito-borne disease in the United States.

There are no vaccines to prevent or medications to treat WNV in people, but most people infected with the disease do not feel sick, the CDC says.

About one in five people who are infected develop a fever and other symptoms, and about one out of 150 infected people develop a serious, sometimes fatal illness, according to the CDC.

The following precautions should be taken when outdoors:

• Avoid outdoor activities at dawn and dusk when mosquitoes are most active.
• Wear long-sleeved shirts and long pants.
• Use mosquito repellent according to the manufacturer’s directions on the label (10 percent or less DEET for children and no more than 30 percent DEET for adults). Always wash treated skin when returning indoors.
• Avoid application of repellents with DEET on infants and small children.
• Cover the arms and legs of children playing outdoors.
• Cover playpens or carriages with mosquito netting.
• Don’t camp overnight near stagnant or standing water.

Eliminate standing water by:

• Getting rid of any water-holding containers (old tires, etc.).
• Raking out puddles and drain ditches, culverts, gutters, pool and boat covers.
• Covering trash containers.
• Chlorinating your backyard pool and empty wading pools when not in use.
• Changing the water in birdbaths daily.
• Keeping grass cut short and shrubbery well trimmed around the house so adult mosquitoes cannot hide there.
• Ponds and stagnant water bodies that do not support fish, frogs or other amphibians that eat mosquito larvae may be treated with a biological control agent such as Bacillus thuringiensis israelensis (BTI). It is suggested that the Department of Health or Conservation be contacted when treatment is considered.

For more information, visit the health department page on the town website.

Click here for more on mosquitoes in Connecticut and the WNV test results