4 New Cases Of West Nile Diagnosed

The number of human cases of West Nile virus in Massachusetts this season more than doubled to seven and public health officials designated Cambridge, Somerville, Watertown and Newton as being at high risk for the mosquito-borne disease.

The Department of Public Health said three men — one in his 40s, one in his 60s, and one in his 80s — were exposed to West Nile virus in Middlesex County. The fourth new case was diagnosed in a female under the age of 19. DPH said she was exposed in Bristol County.

DPH said the Boston area has seen the bulk of the state's West Nile virus activity this year, and on Thursday moved Cambridge, Newton, Somerville and Watertown into the high risk category. Concord, Lexington, Lincoln, Sudbury, Waltham, Wayland, Weston and Winchester were elevated to the moderate risk category. In Bristol County, Dighton, Fall River and Swansea were also moved into the moderate risk category.

In July, Gov. Charlie Baker signed a law that gives the State Reclamation and Mosquito Control Board new powers to fight mosquito-borne illnesses like EEE and West Nile virus when DPH determines there is an elevated risk.

With Thursday's announcement that the number of human cases of West Nile virus was up to seven, Massachusetts surpassed its number of cases for 2019. There were five human cases reported last year, DPH said. Officials said people across Massachusetts should use mosquito repellents with an EPA-registered active ingredient, wear long sleeves and long pants when outdoors to reduce exposed skin, and stay aware of mosquito activity in the community.