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Positive Test for West Nile Virus in Mosquito Pool Confirmed; Take Precautions
The Massachusetts Department of Public Health has advised the Wayland Board of Health that a mosquito pool tested positive for West Nile Virus (WNV) on 8/01/12.  The mosquitoes identified are of the Culex species which are also known as “bridge” vectors that will feed on birds and people.  West Nile Virus can be spread to humans from a mosquito bite.  Last year, a mosquito pool tested positive for WNV on 8/30/11.

The Board of Health obtains mosquito control services from the Eastern Middlesex Mosquito Control Project.  Our program usually includes larviciding in the early spring; however, this spring larviciding was not done due to the extremely dry conditions.  We also treat the catch basins with ALTOSID XR briquettes that last 90 days which has been completed for this season.  Due to the mild winter, dry spring, and hot and rainy conditions this summer, mosquito populations and arbovirus is not typical and is difficult to predict.  We typically do not spray for adult mosquitoes and currently do not have plans to do so.  However, we will be reviewing future mosquito testing results, monitoring the arbovirus situation, and closely working with Dave Henley of the Eastern Middlesex Mosquito Control Project to determine if there is a need to do so.  Spraying does not usually work well with Culex mosquitoes which carry WNV because these mosquitoes spend the night high up in trees and are hard to reach (they are where the birds are), spraying would kill other species of mosquitoes.  At this time, the Board of Health recommends that residents should avoid getting mosquito bites.  Wayland is still at this time considered a low risk area for mosquito-born illness.

In Wayland, mosquitoes pose a health threat especially for West Nile Virus (WNV) between now and early October, or the first frost.  Residents should be aware that mosquito-borne viruses such as WNV, or EEE could cause fever, meningitis or encephalitis.  Early symptoms of these diseases include fever, headache, stiff neck and muscle weakness.

Mosquitoes acquire WNV or EEE after biting an infected bird.  Those mosquitoes can then transmit that virus to a person, horse or to another bird.  Culex mosquitoes that develop in water holding containers are the primary vectors of WNV, while the mosquitoes that transmit EEE originate in wetlands.

Now that we have been notified of the presence of a mosquito pool in Wayland that tested positive for West Nile Virus (WNV), residents are urged to take preventative actions to avoid mosquito bites.

What you should do to avoid mosquito bites

· Be aware of peak mosquito hours - The hours from dusk to dawn are peak biting times for many mosquitoes. Mosquitoes are more active in damp, shady areas, during cloudy humid days, and at night. Consider rescheduling outdoor activities that occur during evening or early morning.  Also, 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 (N, N-diethyl-m-toluamide), permethrin, picaridin (KBR 3023), IR3535 (3-[N-butyl-N-acetyl]-aminopropionic acid)or oil of lemon eucalyptus [p-menthane 3, 8-diol (PMD)], use 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 concentration of 30% 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 the skin.

· More information on choosing and using repellents safely is included in the MDPH Mosquito Repellents fact sheet which can be viewed online at, and also the CDC, or National Pesticide Information Center (NPIC) toll free at 1-800-858-7378 or online at If you can’t go online, contact MDPH at (617)983-6800 for a hard copy of the fact sheet.

· Cover up the arms and legs of children playing outdoors.  Baby carriages and playpens should be covered with mosquito netting.

There are certain actions that residents should take related to West Nile Virus (WNV).

Mosquito proof your home and drain standing water

· To prevent a yard from becoming a source for Culex mosquitoes, homeowners should make a thorough inspection of their property and remove, empty, cover or treat any water-holding containers. During the summer, mosquito larvae can complete their development in water within a week.

· Containers where mosquitoes commonly lay eggs include neglected swimming pools, water in loose fitting pool covers or tarps, unscreened rain barrels, rimless tires, and plastic toys.  Check rain gutters and drains.

· Tires should be disposed of properly or stored inside.

· Rubbish barrels, wheelbarrows and small boats should be covered or stored upside down.

· The water in wading pools and birdbaths should be changed weekly.

· Infrequently used pools should be covered or properly maintained.

· Rainwater collection barrels should be screened, emptied once a week or treated with products containing Bti.

· Some mosquitoes like to come indoors. Keep them outside by having tightly-fitting screens on all of your windows and doors. Fix any holes in screens and screen doors and replace worn weather stripping.

For further information on WNV or EEE, log unto the Massachusetts Department of Public Health web site at or the US Centers for Disease Control and Prevention at If residents have any questions about mosquitoes or how to control them, contact the East Middlesex Mosquito Control Project at 781-899-5730 or visit

Julia Junghanns, R.S.
Director of Public Health