The State of Connecticut Mosquito Management Program announced that mosquitoes trapped in Mianus River Park have tested positive for West Nile Virus (WNV). These are the first positive mosquitoes identified by the Connecticut Agriculture Experiment Station (CAES) in Greenwich this year. In addition to Greenwich, WNV positive mosquito pools have been found in Darien, Milford, New Haven, South Windsor, Stamford and Waterford. The mosquitoes trapped (Culex pipiens, Culex restuans) are generally bird and mammal biting which breed in standing water often found in artificial containers like discarded tires, birdbaths and catch basins.
During 2020, eight Connecticut residents developed WNV-associated illness including two Greenwich residents, the cases were not fatal.
So far this year EEE has not been isolated in mosquitoes in Connecticut. The State Mosquito Management Program continues to trap and test mosquitoes at three testing sites in Greenwich as part of their program and will continue through October 2021.
The Town of Greenwich continues the fight against West Nile Virus by conducting a 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. This year’s program began in June and larvicide is reapplied every four to six weeks. Director of Health, Caroline Calderone Baisley stated, “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. 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.”
Director of Environmental Services, Michael Long, stated, “Although the town’s larvicide program treats catch basins, the general public must be vigilant in eliminating standing water on their own properties and protecting themselves from biting mosquitoes at all times. It is important to recognize that the highest risk of exposure to West Nile Virus infected mosquitoes is during the months of August and September.”
The virus (WNV) is spread to humans by the bite of an infected mosquito, which becomes infected when it bites a bird carrying the virus. WNV is not spread by person-to-person contact or directly from birds to people. General symptoms occur suddenly between 5 – 15 days following the bite of an infected mosquito and range from slight fever, headache, rash, swollen lymph nodes, nausea, malaise and eye pain, to the rapid onset of severe headache, high fever, stiff neck, disorientation, severe muscle weakness, gastrointestinal symptoms, coma or death.
Most people who are bitten by an infected mosquito are able to fight off infection and experience mild or no symptoms at all. Some individuals, including the elderly and persons with compromised immune systems, WNV can cause serious illness that affects the central nervous system. In a minority of infected persons, especially those over 50 years old, WNV can cause serious illness, including encephalitis and meningitis. Infection can lead to death in 3 – 15% of persons with severe forms of the illness.
“The finding of WNV positive mosquitoes in Greenwich marks the time to emphasize that personal protection measures are extremely important against biting mosquitoes during the day and at night,” says Caroline Calderone Baisley, Director of Health. The
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.
• When using mosquito repellents with DEET, use the lowest concentration effective for the time spent outdoors (for example, 6 percent lasts approximately 2 hours and 20 percent for four hours) and wash treated skin when returning indoors. Do not apply under clothing, to wounds or irritated skin, the hands of children, or to infants less than two months old.
• Avoid application of repellents with DEET on infants and small children.
• Cover 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).
✓ Rake out puddles and drain ditches, culverts, gutters, pool and boat covers.
✓ Cover trash containers.
✓ Chlorinate your backyard pool and empty wading pools when not in use.
✓ Change the water in birdbaths daily.
✓ Keep 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 Dept of Health or Conservation be contacted when treatment is considered.
For more information:
Greenwich Department of Health www.greenwichct.org
• Division of Environmental Services (203) 987-1001
Greenwich Conservation Commission (203) 622-6461
Connecticut Department of Energy and Environmental Protection
• Communications Division (860) 424-4184
• DEEP Mosquito Management Program Website www.ct.gov/mosquito