Public Health Officials Respond to West Nile in Arlington

A day after the Massachusetts Department of Public Health announced West Nile Virus (WNV) was detected in mosquitoes collected in Arlington, Lexington’s public health officials released the following information about WNV and avoiding mosquito bites. 

Lexington has not had any WNV-positive mosquitoes or human cases so far this season, according to the Health Division.

Statewide last year, 3,558 mosquito samples were tested for WNV and, as a result, only 121 samples were positive. WNV is most commonly transmitted to humans by the bite of a mosquito infected with the virus. While WNV can infect people of all ages, people over the age of 50 are at higher risk for severe infection.

Culex mosquitoes are the primary vectors of WNV, which is transmitted to humans by the bite of an infected mosquito. The mosquitoes that carry this virus are common throughout the state, and are found in urban as well as more rural areas.While most mosquito species develop in wetlands, Culex mosquitoes prefer to lay their eggs in catch basins, clogged rain gutters, unused tires, buckets and other water-holding containers.

Residents have an important role to play in reducing the risk of WNV and protecting themselves and their loved ones by taking a few, common-sense precautions. Because of the role of Culex mosquitoes transmitting West Nile Virus, residents can help combat this disease by mosquito proofing their property. 

--Limit the number of places around your home for mosquitoes to develop by either draining or getting rid of items that hold water.

--Check rain gutters and drains, as well as empty any unused flowerpots and wading pools, and change water in birdbaths frequently. 

--Install or Repair Screens. Some mosquitoes like to come indoors. Keep them outside by having tightly fitting screens on all of your windows and doors.

You may also avoid mosquito bites by following these simple steps:

-- Be Aware of Peak Mosquito Hours - The hours from dusk to dawn are peak biting times for many mosquitoes. Consider re-scheduling outdoor activities that occur during evening or early morning. Otherwise, take extra care to use repellent and protective clothing.

--Clothing can help reduce mosquito bites. Although it may be difficult to do when it’s hot, wearing long-sleeves, long pants and socks when outdoors will help keep mosquitoes away from your skin.

--Apply Insect Repellent when you go outdoors. Use a repellent with DEET, permethrin, picaridin or oil of lemon eucalyptus, according to the instructions on the product label. DEET products should not be used on infants under two months of age and should be used in concentrations of 30 percent or less on older children. Oil of lemon eucalyptus should not be used on children under three years of age.  Permethrin products are intended for use on items such as clothing, shoes, bed nets and camping gear and should not be applied to skin. 

Over the next few weeks, the Lexington Health Division will continue to work with the Mass DPH and the Eastern Middlesex Mosquito Control Project to monitor the mosquito populations for WNV.

So far this year, 183 acres of wetlands have been treated by helicopter application of Bti granules. Bacillus thuringiensis var. israelensis (Bti) is a microbial insecticide used to control mosquito larvae in wetlands.  Starting next week, crews will begin treating approximately 3,600 catch basins to reduce the number larval mosquitoes.

Information about WNV and reports of WNV activity in Massachusetts during 2011 can be found on the Mass DPH website. Recorded information about WNV is also available by calling the Mass DPH Public Health Information Line at 1-866-MASS-WNV (7968). Facts sheets on WNV and other mosquito-related materials are available at the Office of Community Development. For more information please contact Health Director Gerard Cody at 781-862-0500 x 237 or gcody@lexingtonma.gov.