Hot Weather a Breeding Ground for Mosquitoes and West Nile Virus

Culex Pipiens has buzzed down in Fairfield County. His arrival marks the beginning of the dreaded West Nile Virus season.

The mosquito is the primary carrier of the West Nile virus, which can be fatal in rare cases.

Culex was captured near the bear cage at Beardsley Zoo in Bridgeport on June 21 by staffers on mosquito watch for the Connecticut Agricultural Experiment Station in New Haven.

It was the first – and so far only – member of the species to be trapped in the state this summer and found to be a carrier of West Nile virus, according to Theodore G. Andreadis, medical entomologist and head of the state’s mosquito testing program.

But don’t think you’ll decrease your odds of an encounter with a blood-thirsty mosquito carrying the virus by avoiding the bear cage or the Beardsley Zoo.

That point was made by Kristin Dubay-Horton, Bridgeport director of health, who explained that Culex may have made earlier stops in Fairfield or Easton or other surrounding towns. Its sojourn in Bridgeport was a completely random occurrence.

But with the arrival of steamy weather, lots more of these most unwelcome summer visitors are sure to be found in southern Fairfield County.

Coastal Connecticut, south of the Merritt from Greenwich to New Haven, is the “hot zone” for Culex Pipiens, which breed in storm drains and catch basins rich in organic content, according to Andreadis.

“The hot weather conditions this week are very conducive, indeed ideal, for breeding,” he said. “We fully anticipate seeing an increase in these mosquitoes.”

“It’s time to start paying attention to the mosquitoes,” Andreadis said. “The risk is low, but it will increase in August and September.”

Greenwich residents are urged to continue to participate in the town’s mosquito control efforts by eliminating areas of standing water around their homes, Michael Long, Greenwich director of environmental services. The program will involve conducting a preemptive larviciding program that will include the treatment of public and private roadway catch basins, public school ground catch basins and other property owned and operated by Greenwich if necessary.

Andreadis’ staff trapped and analyzed 20,087 mosquitoes in 13 towns in southeastern Connecticut through July 11 without finding a WNV carrier. 2,956 of those mosquitoes were collected from Hoyt's Swamp and Michigan Road in New Canaan. 

West Nile Virus was first detected in dead birds in coastal towns in Connecticut in 1999 as well as surrounding states.

The virus is transmitted among wild birds primarily by mosquitoes, which may spread the disease to humans and other animals such as horses.

Although most individuals who are infected experience no symptoms or only mild illness which subsides without treatment, it can cause serious disease affecting the central nervous system, especially among the elderly.

Since 1999, 57 Connecticut residents have become ill from infection by the virus and three have died. None of the deaths has occurred in Fairfield County.

Mosquito carriers of the virus require water and a blood meal for reproduction. Therefore, strategies to reduce risk focus on eliminating standing water and taking precautions when outdoors.

David Knauf, Darien’s director of health, recommended the state website as a source for preventive tips.

These include disposing of water-holding containers, cleaning clogged roof gutters, turning over objects such as wading pools and wheelbarrows when not in use and cleaning, chlorinating and covering swimming pools when not in use.

To reduce the risk of being bitten by a mosquito while outdoors, tightly woven long-sleeved shirts, pants, shoes and socks are recommended, as well as mosquito repellent. The mosquitoes are most active at this time of year between 5:30 and 7:30 p.m. and these are good times to be inside. Door and window screens should be in good repair to avoid mosquito bites while indoors. (For a complete list of suggestions and tips, please see below.)

Mosquitoes are also carriers of Eastern Equine Encephalitis and the Jamestown Canyon virus. So far, EEE has not been detected in Connecticut, but nine mosquitoes carrying the Jamestown Canyon virus have been trapped locally so far this year.

Broken down by towns, there were two each found in Easton, Fairfield and Wilton and one each in Darien, New Canaan and Ridgefield. None were caught in Redding, Weston, Westport, Stamford, Greenwich, Trumbull or Shelton.

Mosquitoes carrying the James Canyon virus, which causes relatively mild symptoms and is not potentially fatal, are commonly found in salt marshes.

“Personal measures are extremely important to protect ourselves against biting mosquitoes during the day and at night,” said Long.

The following precautions should be taken:
Avoid outdoor activities at dawn and dusk when mosquitoes are most active.

If you plan to be outdoors for a long period of time, wear long sleeved shirts, long pants and use mosquito repellent according to the manufacturer’s directions on the label (10% or less DEET for children and no more than 30% DEET for adults). Avoid application of repellents with
DEET on infants and small children.

Cover up arms and legs of children playing outdoors and cover playpens or carriages with
mosquito netting.

Don’t camp overnight near stagnant or standing water where mosquitoes are most active.

If you dispose of a dead animal – handle with gloves or bag the animal without touching it.

In addition, Greenwich residents are urged to continue to participate in the Town’s mosquito control efforts by eliminating areas of standing water around their homes which includes:

YARD AND HOME CHECKLIST:
Fill in or drain any low places (puddles, ruts) in yard.

Cover trash containers to keep out rainwater.

Empty plastic wading pools at least once a week and store indoors when not in use.

Fill in tree rot holes and hollow stumps that hold water with sand or concrete.

Keep grass cut short and shrubbery well trimmed around the house so adult mosquitoes cannot hide there.

Get rid of old tires, tin cans, buckets, drums, bottles or any water holding containers.

Keep rain gutters, drains, ditches and culverts clean of weeds and trash so water will drain properly

Repair leaky pipes and outside faucets.

Make sure your backyard pool is properly chlorinated every day.

Change the water in birdbaths and plant pots or drip trays at least once each week.

Eliminate collected water in boat or pool covers.

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) and Bacillus sphaericus (BS).

It is suggested that the Department of Health or Greenwich
Conservation Commission be contacted when treatment is considered.

For more information about the Town’s larviciding program, personal protection and property management recommendations, the State of Connecticut mosquito management program, the following contact sites are available.

The Town of Greenwich Mosquito Management Brochure is available throughout the community and on the Town’s Website.

• Greenwich Department of Health
• Division of Environmental Services: (203) 622-7838.
• Greenwich Conservation Commission: (203) 622-6461.

Connecticut Department of Environmental Protection

• Communications Division:(860) 424-4100
• DEP Mosquito Management Program Website: www.ct.gov/mosquito
• Toll Free Mosquito Information Line: 1-866-968-5463.

Connecticut Department of Public Health: www.ct.gov/dph

• Toxic Hazards Assessment Program: (860) 509-7742
• Epidemiology Program: (860) 509-7994

Connecticut Agricultural Experiment Station: (860) 974-8604

• Website: www.ct.gov/caes

Department of Agriculture: (860) 713-2505

• Website: www.ct.gov/doag

- Local editor Barbara Heins contributed to this report.