By Anne White
The State of Connecticut Mosquito Management Program has confirmed that mosquitoes trapped near the Eastern Greenwich Civic Center in Old Greenwich have tested positive for West Nile Virus (WNV). These are the first positive cases identified in Greenwich this year by the Connecticut Agriculture Experiment Station (CAES). Along with Greenwich, WNV-positive mosquito pools have also been detected in Darien, Norwalk, New Canaan, New Haven, and Stamford.
The mosquitoes in question, Culex pipiens, are known to bite both birds and mammals and typically breed in standing water found in artificial containers such as discarded tires, birdbaths, and catch basins. In 202 3, five Connecticut residents contracted WNV-associated illnesses, none of which were fatal. Thus far in 202 4, no Eastern equine encephalitis (EEE) has been isolated in Connecticut mosquitoes. The State Mosquito Management Program continues to trap and test mosquitoes at three sites in Greenwich as part of their ongoing efforts, which will continue through October 2024.
Greenwich’s preemptive measures against WNV include a larviciding program targeting public and private roadway catch basins, school grounds, and other town-owned properties. This year’s program began in June, with larvicide applications reoccurring every four to six weeks. Director of Health Caroline Calderone Baisley noted, “Controlling the mosquito population in the larval stage through the application of larvicide is 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.”
Michael Long, Director of Environmental Services, emphasized the importance of public vigilance in eliminating standing water on private properties and protecting against mosquito bites. “The highest risk of exposure to West Nile Virus-infected mosquitoes is during August and September,” he stated.
WNV is transmitted to humans through the bite of an infected mosquito, which acquires the virus by biting an infected bird. The virus is not spread through person-to-person contact or directly from birds to people. Symptoms of WNV infection can appear suddenly between 5-15 days after being bitten and can range from mild (fever, headache, rash) to severe (high fever, stiff neck, disorientation, severe muscle weakness, coma, or death). While most people experience mild or no symptoms, the elderly and individuals with compromised immune systems are at greater risk for serious illness affecting the central nervous system, including encephalitis and meningitis. Severe illness can result in death in 3-15% of cases.
Caroline Calderone Baisley, Director of Health, stressed the importance of personal protection against mosquito bites. Recommended precautions include:
- Avoiding outdoor activities at dawn and dusk when mosquitoes are most active.
- Wearing long-sleeved shirts and long pants.
- Using mosquito repellent according to the manufacturer’s directions (10% or less DEET for children and no more than30% DEET for adults), and washing treated skin upon returning indoors.
- Avoiding DEET-based repellents on infants and small children.
- Covering children’s arms and legs when they play outside.
- Using mosquito netting over playpens and carriages.
- Avoiding camping near stagnant or standing water.
Residents are also urged to eliminate standing water by:
- Removing water-holding containers like old tires.
- Raking puddles and draining ditches, culverts, gutters, and pool covers.
- Covering trash containers.
- Keeping grass short and shrubbery trimmed to prevent mosquitoes from hiding.
- Chlorinating backyard pools and emptying wading pools when not in use.
- Changing birdbath water daily.
