The Massachusetts Department of Public Health (DPH) announced Thursday four additional human cases of West Nile virus (WNV) in the state.
This brings the total number of WNV cases to seven. Three of the four cases are male – one in his 40s, one in this 60s, and one in his 80s. All were exposed to WNV in Middlesex County. WNV was also diagnosed in a female under the age of 19 with exposure in Bristol County.
Most WNV virus activity this year has been focused in an area around Boston and includes parts of Norfolk, Middlesex, and Essex counties.
In 2019, there were five human cases of WNV infection.
WNV is usually transmitted to humans through the bite of an infected mosquito. While WNV can infect people of all ages, people over the age of 50 are at higher risk for severe disease. Most people infected with WNV will have no symptoms.