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State Reports Positive Mosquitoes for West Nile Virus in Stamford

Hartford – The State Mosquito Management Program today announced that mosquitoes trapped in Stamford on June 27, 2012 have tested positive for West Nile virus (WNV). These results represent the first positive mosquitoes identified in the state by the Connecticut Agricultural Experiment Station (CAES) this year.

“The West Nile virus season has started,” said Dr. Louis Magnarelli, Director, CAES. “The very high numbers of Culex pipiens, mosquitoes feeding on birds, warm weather, and presence of standing water are some of the factors which favor amplification of this virus in nature.”

“The identification of mosquitoes positive for West Nile virus in Connecticut serves as a reminder to residents and visitors to take steps to prevent mosquito bites which can cause mosquito-borne illnesses,” said Department of Public Health Commissioner Dr. Jewel Mullen. “Especially this holiday weekend, when many of us will be spending time with family and friends outdoors at picnics or watching fireworks, remember to use bug spray, wear long sleeves and long pants, and avoid being outdoors during dawn and dusk when mosquitoes are most active.”

The number of Culex pipiens at selected sites is averaging approximately 30 to 50% higher than average collections over the previous six years. Culex pipiens is the species of mosquito most commonly associated with West Nile virus in Connecticut.

Officials are asking residents to do what they can to reduce the amount of standing water available for mosquito breeding around their homes by:

  • Emptying standing water from used or discarded tires that may have accumulated on your property (e.g. tire swings).
  • Disposing of cans, plastic containers, ceramic pots or similar water-holding containers that have accumulated on your property. Do not overlook containers that have become overgrown by vegetation.
  • Drilling holes in the bottom of recycling containers that are left out of doors. Drainage holes that are located on the sides collect enough water for mosquitoes to breed in.
  • Cleaning clogged roof gutters on an annual basis, particularly if the leaves from surrounding trees have a tendency to plug up the drains. Roof gutters are easily overlooked but can produce millions of mosquitoes each season.
  • Turning over plastic wading pools when not in use. A wading pool becomes a mosquito producer if it is not used on a regular basis.
  • Turning over wheelbarrows and do not allow water to stagnate in bird baths. Both provide breeding habitat for domestic mosquitoes. Change water in bird baths and wading pools on a weekly basis.
  • Aerating ornamental pools or stocking them with fish. Water gardens are fashionable but become major mosquito producers if they are allowed to stagnate.
  • Cleaning and chlorinating swimming pools that are not being used. A swimming pool that is left untended by a family that goes on vacation for a month can produce enough mosquitoes to result in neighborhood-wide complaints. Be aware that mosquitoes may even breed in the water that collects on swimming pool covers.
  • Using landscaping to eliminate standing water that collects on your property. Mosquitoes can develop in any puddle that lasts more than seven to ten days during the summer.

In 2011, WNV-positive mosquitoes were trapped in 30 municipalities; the first were trapped on June 21. In addition, last year nine Connecticut residents were identified with WNV infections.

Monitoring and risk assessment for WNV emphasizes mosquito trapping and testing results. The CAES maintains a network of 91 mosquito-trapping stations in 72 municipalities throughout the state. Mosquito traps are set Monday – Thursday nights at each site every ten days on a rotating basis. Mosquitoes are grouped (pooled) for testing according to species, collection site, and date. Each pool is tested for the presence of viruses of public health importance. Positive findings are reported to local health departments and on the CAES web site at

For information on West Nile virus and what you can do to prevent getting bitten by mosquitoes, visit the Connecticut Mosquito Management Program Web site at Mosquito pools that test positive for WNV and EEE, as well as human cases of these illnesses, will also be posted on the Connecticut Mosquito Management Program Web site.1

1Department of Public Health, "State Reports Positive Mosquitoes for West Nile Virus in Stamford"