Massachusetts reports 3 new West Nile virus cases, bringing total to 11

Massachusetts public health officials reported three additional human cases of West Nile virus on Friday, bringing the state’s total for the year to 11 infections. The Massachusetts Department of Public Health stated that the newly confirmed patients include a man in his 90s exposed in Middlesex County, alongside two men likely exposed in Suffolk County—one in his 60s and another whose age was not specified.

State health data shows that the majority of this year’s human cases are concentrated in Middlesex and Suffolk counties. Previously announced cases in Suffolk County involved three men in their 50s and 70s, while Middlesex County infections included a woman in her 30s and men in their 60s, 80s, and 90s. An additional case was reported in a man in his 60s in Worcester County.

Following the detection of these cases, public health authorities designated high-risk areas for the mosquito-borne virus. Boston, Brookline, Cambridge, Chelsea, Everett, Malden, Newton, Revere, Somerville, Watertown, and Winthrop remain under a high-risk designation, while the remainder of the state stays at a moderate risk level. The Department of Public Health updates these risk levels daily on its official website.

Mosquito Surveillance and Virus Spread

Since the state identified its first West Nile virus-positive mosquito samples in mid-June, testing has revealed 338 positive samples across the commonwealth. According to state figures, positive mosquito samples have turned up in every Massachusetts county except Nantucket.

In addition to West Nile virus, officials reported that Eastern equine encephalitis (EEE) has been detected in 26 mosquito samples this year. State records show no reported animal or human cases of EEE so far.

Boston’s commissioner of public health, Bisola Ojikutu, emphasized the potential danger in a statement reported by Boston.com, noting that West Nile virus can result in very serious illness and may pose serious danger to older and more vulnerable members of our communities. Boston.com also reported that positive mosquito test samples have surfaced in multiple Boston neighborhoods this summer, including Jamaica Plain, Dorchester, Mattapan, South Boston, Allston, Charlestown, East Boston, Roslindale, and West Roxbury.

Symptoms and Prevention Guidance

Health officials report that approximately 80% of individuals infected with West Nile virus experience no symptoms. Those who do fall ill typically develop symptoms two to six days after an infected mosquito bite, ranging from fevers and headaches to body aches, nausea, vomiting, a rash, or swollen lymph glands. Less than 1% of infected people develop severe neurological illnesses such as encephalitis or meningitis. Older adults and immunocompromised individuals face a significantly higher risk of severe complications.

To minimize infection risks, the Department of Public Health advises residents to take specific precautions:

• Wear long-sleeved clothing and long pants while outdoors.
• Apply insect repellent containing DEET or other EPA-approved repellents.
• Drain standing water from outdoor items such as flower pots, roof gutters, birdbaths, and kiddie pools to eliminate mosquito breeding sites.
• Adjust outdoor activity schedules to avoid peak mosquito hours lasting from dusk until dawn.