WESTFORD — Mosquitoes carrying the West Nile virus (WNV) have been detected in Westford, the Massachusetts Department of Public Health (MDPH) announced this week.
Mosquitoes collected in town tested positive for the virus, according to an Aug. 12 MDPH release. The town issued its own notice outlining prevention tips and measures officials are taking to reduce risk as well.
WNV is most often spread to humans through the bite of an infected mosquito. People of any age can become infected, but those over 50 are at higher risk for severe illness.
About 80% of infected individuals show no symptoms. The remaining 20% may develop fever, headache, body aches, vomiting, swollen lymph glands, or a skin rash on the chest, stomach and back. Severe illness occurs in fewer than 1% of cases, and most mild cases resolve on their own.
Prevention tips
Since infection is spread through mosquito bites there are steps that individuals can take to reduce chances of being bitten. The MDPH advises residents to:
- Schedule outdoor activities outside peak mosquito hours (dusk to dawn).
- Wear long sleeves and pants to limit exposed skin.
- Use insect repellents containing DEET, permethrin, picaridin, IR3535, or oil of lemon eucalyptus.
- Remove standing water around homes, including in recycling bins, clogged gutters, bird baths, wading pools, and old tires.
Pet owners should also remove standing water and empty wading pools after heavy rains to reduce mosquito breeding sites.
Mosquito control
On Aug. 14, the Central Massachusetts Mosquito Control Project (CMMCP) conducted targeted spraying in Westford. Officials said residents do not need to relocate during spraying, as the pesticide poses minimal risk to human health and the environment when used as directed. CMMCP will continue normal spray operations.
The town will keep working with MDPH and CMMCP to monitor mosquito populations, collect data and determine next steps to reduce the risk of WNV.
Statewide situation
The MDPH reports that WNV risk is currently high in several Massachusetts communities. The state public health laboratory confirmed the first positive WNV mosquitoes of the year on June 17. Since then, 168 positive mosquito samples have been detected in counties including Barnstable, Berkshire, Bristol, Dukes, Essex, Franklin, Hampden, Middlesex, Norfolk, Plymouth, Suffolk, and Worcester. No human cases have been reported in the state so far in 2025.
Mosquito trapping and testing began the week of June 16. August and September are typically the peak months for mosquito-borne illnesses in Massachusetts, when higher numbers of infected birds and mosquito populations in concentrated areas lead to elevated infection rates among mosquitoes.
Climate change may also be lengthening mosquito season into the fall, though the shift happens gradually over years. According to MDPH, recent seasons have seen more WNV cases than in previous decades.
