Mosquitoes test positive for West Nile Virus in Massachusetts

Residents urged to use bug spray, personal protection to avoid getting bitten

BOSTON (WWLP) – The Massachusetts Department of Public Health announced on Thursday that West Nile Virus was found in mosquitoes for the first time in 2016.

According to the Mass. DPH, the West Nile Virus was discovered in three mosquito samples that were tested at the Massachusetts State Public Health Laboratory. The mosquitoes were collected on July 1st in the City of Worcester.

No human or animal cases of WNV or Eastern Equine Encephalitis have been found this year so far, according to the Mass. DPH. Also, there is no elevated risk level or risk level change.


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“This is an expected finding at this time of year and given the heat and dry conditions we have been experiencing, we are expecting to see more and more WNV activity,” said DPH State Epidemiologist Dr. Al DeMaria. “Tools for prevention include using a mosquito repellent with an EPA-registered ingredient according to the directions on the label, wearing clothing to reduce exposed skin when weather permits, draining standing water to prevent mosquito breeding and repairing window screens to keep mosquitoes out of your home.”

In 2015, there were 10 human cases of WNV infections in Massachusetts. The WNV symptoms tend to include fever and flu-like illness, and in rare cases, more severe illness can occur.

Below are tips from the DPH on how to avoid mosquitoes borne illnesses:

Avoid Mosquito Bites

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.

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.

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.

Protect Your Animals

Animal owners should reduce potential mosquito breeding sites on their property by eliminating standing water from containers such as buckets, tires, and wading pools – especially after heavy rains.

Water troughs provide excellent mosquito breeding habitats and should be flushed out at least once a week during the summer months to reduce mosquitoes near paddock areas.

Horse owners should keep horses in indoor stalls at night to reduce their risk of exposure to mosquitoes. Owners should also speak with their veterinarian about mosquito repellents approved for use in animals and vaccinations to prevent WNV and EEE.

If an animal is diagnosed with WNV or EEE, owners are required to report to DAR, Division of Animal Health by calling 617-626-1795 and to the Department of Public Health (DPH) by calling 617-983-6800.

More information, including all WNV and EEE positive results from 2014, can be found on the Arbovirus Surveillance Information web page at www.mass.gov/dph/mosquito or by calling the DPH Epidemiology Program at 617-983-6800.

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