The risk for West Nile virus is high in 10 cities and towns in Massachusetts, including Boston, public health officials say.

The communities now listed at high risk for the mosquito-borne illness are Acton, Bedford, Billerica, Boston, Brookline, Carlisle, Chelmsford, Dracut, Lowell and Newton, a map from the Massachusetts Department of Public Health shows.

A map shows towns at high risk of West Nile virus in Massachusetts. Massachusetts Department of Public Health

More than 150 samples of mosquitoes in Massachusetts have tested positive for West Nile this summer, but so far there have not been any human cases of the virus in 2025.

What is West Nile virus?

There were 19 human cases of West Nile virus confirmed last year in Massachusetts. The virus is spread from the bite of

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