West Nile Virus Confirmed in Mass. for First Time This Year

Health officials are reminding Bay State residents that they play an important role in protecting themselves from mosquito-borne illnesses like West Nile Virus

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West Nile virus has been detected in mosquitoes in Massachusetts for the first time this year, state health officials announced Wednesday.

The virus was found by the Massachusetts State Public Health Laboratory in a mosquito sample collected on July 11 in the town of Easton. No cases of West Nile or Eastern equine encephalitis (EEE) have been found in people or animals yet this year. There is no elevated risk level or risk-level change, health officials said.

“West Nile virus is part of summer in Massachusetts, and we expect to see infected mosquitoes at this time of year,” Public Health Commissioner Margret Cooke said. “Now is the time to start taking steps to avoid mosquito bites. While WNV can cause serious illness, there are things that you can do to protect yourself and your loved ones.”

West Nile virus is usually transmitted to humans through the bite of an infected mosquito. It can infect people of all ages, though people over the age of 50 are at higher risk for severe disease. Most people infected with the virus have no symptoms. When present, symptoms include fever and flu-like illness.

There were 11 human cases of West Nile Virus in 2021. Health officials are reminding Bay State residents that they play an important role in protecting themselves from mosquito-borne illnesses.

“Simple actions can help protect you from mosquito bites and the diseases they can cause,” State Epidemiologist Dr. Catherine M. Brown said. “Use a mosquito repellent with an EPA-registered ingredient, wear clothing to reduce exposed skin, drain standing water and repair window screens. We also encourage you to make it a habit to check the mosquito-borne disease webpages on so you know when and where WNV activity is occurring.”

It's mosquito season again! Here are some things to know about the most common mosquito-borne disease and how to protect yourself.

Protect yourself from West Nile Virus

  • Avoid mosquito bites: Apply insect repellent when outdoors and use a repellent that contains DEET (except on infants under two months of age, and not in concentrations higher than 30% on older children).
  • Be aware of peak mosquito hours: The hours from dusk to dawn are peak biting times for many mosquitoes.
  • Wear long clothing: Long sleeves, long pants and socks when outdoors can help keep mosquitoes away from your skin.
  • Mosquito-proof your home: Drain standing water, which is where mosquitoes lay eggs. Drain or discard items around your home that hold water. Check rain gutters and drains. Empty unused flowerpots and wading pools. Install or repair screens on all of your windows and doors in order to have tightly-fitting screens that keep mosquitoes outside.
  • Protect your animals: Owners should speak with their veterinarian about mosquito repellents approved for use in animals and vaccinations to prevent WNV and Eastern Equine Encephalitis. If an animal is diagnosed with WNV or EEE, owners are required to report to the Massachusetts Department of Agricultural Resources’ Division of Animal Health by calling 617-626-1795 and to the DPH by calling 617-983-6800.

More information, including all West Nile virus and EEE positive results can be found on the state's website or by calling the DPH Epidemiology Program at 617-983-6800.

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