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The original item was published from 9/23/2022 2:54:37 PM to 10/31/2022 12:00:00 AM.

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Health Department

Posted on: September 23, 2022

[ARCHIVED] First West Nile Virus Human Case in Greenwich this year

West Nile Virus Confirmed in Greenwich Resident


Today the Greenwich Department of Health was notified by the Connecticut Department of Public Health that a resident from Greenwich has tested positive for West Nile Virus (WNV). The individual, between 80‑89 years of age became ill at the end of August.  There have been four cases of human WNV infection acquired in CT so far this year.  


“This case of human illness demonstrates that WNV can cause serious illness and whenever the virus is present, there is a potential for human infection.  There will continue to be infected mosquitoes until the first frost so persons, particularly those older than 50 years of age, must take personal protection precautions to avoid mosquito bites when outdoors at any time of day, especially during twilight hours,” said Caroline C. Baisley, Director of Health.


Human cases of WNV have been confirmed in Fairfield, New Haven and Litchfield counties.  So far this year WNV has been isolated in mosquitoes in twenty-four (24) towns, including Greenwich.


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 into early fall.  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. Although this measure helps reduce the mosquito population, it certainly does not eliminate it.  Residents are, therefore encouraged to protect themselves.”


Director of Environmental Services, Michael S. 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 in both humans and mosquitoes within Greenwich emphasizes the need for immediate personal protection measures 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.
  • 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:

ü  Getting rid of any water holding containers (old tires, etc.).

ü  Rake out puddles and drain ditches, culverts, gutters, pool and boat covers.

ü  Cover trash containers.

ü  Chlorinate your backyard pool and empty wading pools when not in use. 

ü  Change the water in birdbaths daily.

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

ü    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:  

            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) 987-1001

Greenwich Conservation Commission              (203) 622-6461

Connecticut Department of Energy and Environmental Protection

Communications Division                                       (860) 424-4184

CT DEEP Mosquito Management Program 

        Toll Free Mosquito Information Line            1-866-968-5463


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