Mosquitoes Test Positive for West Nile Virus in Greenwich

The State of CT Mosquito Management Program announced that mosquitoes trapped near the Eastern Civic Center in Old Greenwich on July 19, 2017 have tested positive for West Nile Virus.

These are the first positive mosquitoes identified by the Connecticut Agriculture Experiment Station (CAES) in Greenwich this year. In addition to Greenwich, West Nile Virus positive mosquito pools have been found in West Haven and South Windsor.

The mosquitoes trapped (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.

During 2016, one CT resident developed WNV-associated illness, the case was not fatal.

The State Mosquito Management Program continues to trap and test mosquitoes at three testing sites in Greenwich as part of their program. The State trapping program will continue through October 2017.

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.

“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  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.”

“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,” said Director of Environmental Service Michael Long.

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 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% or less DEET for children
and no more than 30% DEET for adults). Always wash treated skin when returning indoors.
• 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
Department of Health or Conservation be contacted when treatment is considered.


Email news tips to Greenwich Free Press editor [email protected]
Like us on Facebook


Subscribe to the daily Greenwich Free Press newsletter