Massachusetts Reports First Human West Nile Virus Case of 2025

In a concerning development, Massachusetts has identified its first human case of West Nile virus (WNV) for the year 2025. The Massachusetts Department of Public Health announced that a woman in her 70s residing in Middlesex County contracted the mosquito-borne illness, marking the state's initial reported human infection this season. The case was confirmed on September 2nd, and health officials emphasize that the virus remains widespread among local mosquito populations, with over 300 infected mosquitoes found across 12 counties.

Public Health Commissioner Robbie Goldstein highlighted the importance of vigilance, stating, "West Nile virus can be a very serious disease, and its presence in mosquitoes remains high right now in Massachusetts." Despite the cooler temperatures typical of September, the risk posed by WNV persists, especially in areas with high mosquito activity. Residents are urged to take protective measures such as avoiding outdoor activities during dusk and dawn, draining standing water where mosquitoes breed, and ensuring screens on windows and doors are intact.

When outdoors, using EPA-registered insect repellents and wearing long-sleeved clothing can significantly reduce risk. Pet owners should consult vets about safe insect repellents and vaccines for their animals, and report any suspected infections.

While many infected individuals remain asymptomatic, some may develop symptoms like high fever, severe headaches, confusion, muscle weakness, and lack of coordination. Elderly individuals and those with weakened immune systems are at a higher risk of severe illness. The Department of Public Health also noted that the mosquito species testing positive for Eastern equine encephalitis (EEE) has been detected in 18 samples, although no human or animal cases have been reported for EEE this year.

In 2024, Massachusetts recorded 19 human cases of West Nile virus and four cases of EEE, including one fatality. State epidemiologists warn that mosquito activity will continue until the first hard frost, reinforcing the importance of protective measures for residents.

For detailed information on mosquito-borne disease risks and safety precautions, residents are encouraged to visit mass.gov/mosquito-borne-diseases or contact the DPH Division of Epidemiology at 617-983-6800.