West Nile Virus Detected in Mosquito Sample, Spraying Scheduled

WORCESTER, Mass. - The Massachusetts Department of Public Health (MDPH) announced that West Nile Virus (WNV) has been detected in mosquitoes collected from a trap site. The city's WNV risk level remains Moderate and no human cases have been reported.

In coordination with the municipality, the Central Massachusetts Mosquito Control Project (CMMCP) has scheduled truck-mounted pesticide applications on Tuesday, Aug. 26 after 9 p.m. (weather permitting), where the positive WNV insects were found. The areas to be sprayed can be viewed on the attached map. Please note, Institute Park will not be sprayed.

Residents may opt out of having their property sprayed during wide-area pesticide application by following instructions on the Massachusetts Department of Agricultural Resources website: mass.gov/how-to/how-to-request-an-exclusion-or-opt-out-from-wide-area-pesticide-applications .

Personnel from CMMCP are tentatively planning to be in Worcester on Sept. 2 to respond to mosquito-related concerns from residents. Requests for pesticide spraying in limited areas using truck-mounted equipment may be considered on this date, but spraying will also be dependent on weather conditions and current mosquito thresholds. No aerial spraying is planned at this time.

CMMPC's residential request spray program will end the week after Labor Day. Residential requests will no longer be accepted after Monday, Aug. 25, 2025.

In addition to mosquito spraying, the CMMCP offers a variety of services such as ditch maintenance and abandoned swimming pool treatment. Residents may access forms for all service requests on the CMMCP website at cmmcp.org , or they may call 508-393-3055, Monday through Friday between 7 a.m. - 3:30 p.m. Information about the products and Integrated Pest Management program used by the CMMCP is available at cmmcp.org/pesticide-information .

The CMMCP's full 2025 spraying schedule is available at cmmcp.org/home/pages/2025-spray-schedules , and specific areas to be sprayed will be posted both on its website and phone system (508-393-3055) each day after 3:30 p.m. The scheduled dates and locations are subject to change due to weather conditions, mosquito populations, mosquito virus activity, and/or special event spraying. According to the CMMCP, the mosquito control program will cease once cool nighttime temperatures become predominant in the area.

The municipality will notify residents in specific areas and neighborhoods to be sprayed via email, social media, and text. Residents interested in receiving these alerts should ensure that they are registered for ALERTWorcester ( worcesterma.gov/emergency-communications/alertworcester ) with an up-to-date email and/or phone number. Additional alerts will be sent if cases of mosquito-borne illness are detected and necessitate emergency spraying.

Residents are advised to observe the following precautions if their area is being sprayed:

• Close street-facing windows and turn off any "outside air" settings on air conditioners.
• Keep pets inside between sunset and midnight, and do not let children play near or behind truck-mounted applicators when they are in use.
• Remain inside during the application and for 15-20 minutes afterwards.
• Wash off any vegetables from home gardens after spraying and before consuming them.

Accidental exposure is not expected to cause any health concerns in most people, although anyone who suffers from chemical sensitivities or feels that spraying may aggravate a preexisting health condition should consult their physician and take special measures to avoid exposure if necessary. Accidental exposure to pets should also not cause a problem since the pesticide being used is similar to ones used for flea and tick control.

To avoid mosquito bites and the diseases they can transmit, residents are encouraged to practice the "5 Ds:"

• DRESS in long sleeves and pants when possible. Cover up during periods of mosquito activity.
• DEET is an effective insect repellent. Always follow the label instructions.
• DAWN & DUSK are mosquitoes' most active periods.
• DRAIN water from containers weekly. Avoid standing water, such as rain collecting in open bins, buckets, or toys.

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

While WNV can infect people of all ages, people over the age of 50 are at higher risk for severe infection. Most people infected with WNV will have no symptoms, although some may experience fever, flu-like illness, and-in rare cases-more severe illness. The Worcester Division of Public Health (WDPH) works closely with the MDPH and other agencies on monitoring WNV and other mosquito-borne illnesses. If a case is detected within the city, WDPH Nursing staff will follow their regular case management procedure. There were 19 human cases reported in Massachusetts in 2024.

More information from MDPH, including all WNV and Eastern equine encephalitis (EEE) positive results in the state, can be found at mass.gov/mosquito-borne-diseases , 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 it to the Massachusetts Department of Agricultural Resources, Division of Animal Health by calling 617-626-1795, and to MDPH by calling 617-983-6800.