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West Nile Virus Found in Mosquitoes in Massachusetts

Practice-the-5-Ds.png For Immediate Release: 7/14/2022 2:05 pm

WORCESTER – The Massachusetts Department of Health (MDPH) announced that West Nile Virus (WNV) was detected in mosquitoes in Massachusetts for the first time in 2022. The sample was collected in the town of Easton. No cases of WNV have been detected in humans or animals, and MDPH reports that there is no elevated risk level or risk-level change associated with the positive sample.

There were 11 human cases of WNV in Massachusetts in 2021. It is usually transmitted to humans through the bite of an infected mosquito, and individuals over the age of 50 are at higher risk of disease. While most people infected with WNV will have no symptoms, some may experience fever, flu-like illness, and—in rare cases—more severe illness.

Residents are advised to follow the “5 Ds” to protect against WNV and other mosquito-borne illness:

  • DRESS in long sleeves and pants when possible. Cover up during periods of mosquito activity to prevent bites.
  • DEET is an effective insect repellent. Always follow the label instructions.
  • DAWN & DUSK are mosquitoes’ most active periods. Consider rescheduling outdoor activities that occur during evening or early morning.
  • DRAIN water from containers such as buckets, tires, wading pools, and water troughs. Avoid standing water, such as rain collecting in open bins or toys.

In addition to DEET, clothing treated with insect repellent is available, and permethrin—the repellent commonly used—can be applied to treat clothing manually. Installing and repairing screens will also help to keep mosquitoes out of homes.

The city continues to partner with the Central Massachusetts Mosquito Control Project (CMMCP) to offer comprehensive mosquito control services and programs. The CMMCP plans to spray areas of Worcester on July 19 and 26, and residents can request service at

The CMMCP also offers education about mosquito biology and personal protection, mosquito surveillance, ditch maintenance, research, tire recycling, beaver control, and mosquito larval control.

More information from MDPH, including all WNV and Eastern equine encephalitis (EEE) positive results in the state, can be found at, or by calling the MDPH Division of Epidemiology at 617-983-6800.

If an animal is suspected of having 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 MDPH by calling 617-983-6800.

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