Viruses Spreading In Massachusetts Mosquitoes

Ruzanna Harutyunyan's picture

The Massachusetts Department of Public Health (DPH) announced that West Nile Virus has been found in mosquitoes in the towns of Westborough and Westford. This follows yesterday’s finding of a positive mosquito sample in Boston and one from Walpole in July. Eastern equine encephaliti (PDF) | RTF (EEE) virus has been found twice in mosquitoes from Freetown.

“Summer is here and along with it, mosquitoes and their viruses,” said DPH State Epidemiologist Dr. Al DeMaria. “If you look at where the WNV mosquitoes have been found on a map, you can see that the virus is distributed in Worcester, Middlesex, Suffolk and Norfolk counties. We shouldn’t think about this virus as occurring only in certain towns. We consider it to be present in eastern Massachusetts.”

There have been ten human cases of WNV in Massachusetts during the last five years. While WNV can infect people of all ages, people over the age of 50 are at higher risk for severe disease. WNV is usually spread to humans through the bite of an infected mosquito. There was one human case of EEE during 2008; however there were 13 cases with 6 deaths from 2004 through 2006. EEE is usually spread to humans through the bite of an infected mosquito. EEE is a serious disease in all ages and can even cause death.

“When you go out to enjoy the summer weather this weekend, the mosquitoes will be enjoying it too. Don’t forget the bug spray,” added DeMaria.

Positive mosquito results from 2009 can be found on the Arbovirus Surveillance Information web page at

People have an important role to play in protecting themselves and their loved ones from illnesses caused by mosquitoes.


Avoid Mosquito Bites

* Be Aware of Peak Mosquito Hours. The hours from dusk to dawn are peak biting times for many mosquitoes. Consider rescheduling outdoor activities that occur during evening or early morning.

* Clothing Can Help Reduce Mosquito Bites. Wearing long-sleeves, long pants and socks when outdoors will help keep mosquitoes away from your skin.

* Apply Insect Repellent when Outdoors. Use a repellent with DEET (N, N-diethyl-m-toluamide), permethrin, picaridin (KBR 3023), oil of lemon eucalyptus [p-methane 3, 8-diol (PMD)] or IR3535 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% or less on older children. Oil of lemon eucalyptus should not be used on children under three years of age.

Mosquito-Proof Your Home

* Drain Standing Water. Mosquitoes lay their eggs in standing water. Limit the number of places around your home for mosquitoes to breed by either draining or discarding items that hold water. Check rain gutters and drains. Empty any unused flowerpots and wading pools, and change water in birdbaths frequently.

* Install or Repair Screens. Keep mosquitoes outside by having tightly-fitting screens on all of your windows and doors.