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The original item was published from 10/4/2019 4:09:08 PM to 11/1/2019 12:00:00 AM.

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Health Department

Posted on: October 4, 2019

[ARCHIVED] Eastern Equine Encephalitis (EEE) / West Nile Virus (WNV) Information

The Greenwich Department of Health would like to remind all residents that West Nile Virus (WNV) was isolated in mosquitoes in the month of August in the Old Greenwich area. To date, the Eastern Equine Encephalitis (EEE) virus has not been isolated in mosquitos collected/analyzed in Greenwich.  Positive mosquito pools for WNV have been found in Greenwich, Bridgeport, Chester, Darien, East Haven, Groton, Hartford, Manchester, Middlefield, Monroe, New Canaan, New Haven, Newington, North Haven, North Stonington, Norwalk, Plainfield, South Windsor Stamford, Stonington, Voluntown, West Hartford, West Haven and Wethersfield.  The mosquitoes (Culex pipiens) carrying WNV in Greenwich are generally bird and mammal biting which breed in standing water often found in artificial containers like discarded tires, birdbaths and catch basins.  So far this year, in the State of Connecticut there has been one human case of WNV in a Danbury resident. 

West Nile Virus (WNV)

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 can 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 Eastern Equine Encephalitis (EEE)

Eastern Equine Encephalitis (EEE)is a rare but serious disease caused by the EEE virus.  Mosquitos spread the EEE virus.  The EEE virus is carried by birds that live in freshwater swamps and is generally found only in these birds and in mosquitoes that feed on birds but not people. In some years, however, many birds get infected and other types of mosquitoes pick up the EEE virus that also bite people and horses.   The risk of getting EEE is highest from late July through September. The virus is spread by adult mosquitoes, which are killed by a hard frost in the fall.  The EEE virus is not spread by people and horses with the disease. 

To date, the State has reported the EEE virus is mosquitos within seventeen (17) towns (Bethany, Chester, Groton, Haddam, Hampton, Killingworth, Ledyard, Lyme/Old Lyme, Madison, Middlefield, North Stonington, Plainfield, Shelton, South Windsor, Stamford, Stonington, Voluntown).  So far, in Connecticut, there have been four (4) human cases of EEE with three (3) fatalities.  Towns with positive EEE virus in mosquitos and human fatalities especially, have placed restrictions and/or cancelled outdoor activities in the community from an hour before dusk to down.

Most people infected with EEE virus do not become ill. When symptoms do occur, they can range from mild fever and headache to coma. Other symptoms include high fever, fatigue, muscle aches, neck stiffness, tremors, or confusion. Severe cases include inflammation of the brain (encephalitis) which can lead to coma, convulsions, and death.  Symptoms usually occur 3 to 10 days after an infected mosquito bites a person.  There is no cure for EEE, and 3 of every 10 people who get the disease die from it. Doctors provide supportive treatment, lower the fever, and ease the pressure on the brain and the spinal cord. Some people who survive this disease will be permanently disabled and only about half recover completely.

The Town of Greenwich, through the Department of Health, conducts a preemptive larviciding program, that 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.  The program routinely begins in June and larvicide is reapplied every four to six weeks through September.  The 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.  Adult infected mosquitos cannot be controlled with larvicide.  Therefore, residents are encouraged to protect themselves whenever they are outdoors.  Should the EEE virus be isolated in Greenwich, restrictions on outdoor activities (one hour before dusk to dawn) will most likely not be applied by the Department of Health, since the risk of getting bitten by a mosquito infected with EEE virus is close to zero, due to the late/ending mosquito season, cooler weather approaching and declining mosquito population.  Should the situation change, restrictions will be considered.”

Director of Environmental Services, Michael Long, stated that general public must still be vigilant in eliminating standing water on their own properties and protect themselves from biting mosquitoes at all times.”

Precaution Measures

To avoid mosquito bites 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
  • 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.

For more information on EEE and WNV, visit the links below:

Connecticut Mosquito Management Program

Center of Disease Control and Prevention

Connecticut Department of Public Health

Greenwich Department of Health

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