Massachusetts Dept. of Public Health announces fourth human case of West Nile virus

BOSTON — The Massachusetts Department of Public Health (DPH) announced the fourth human case of West Nile virus (WNV) in the state this year.

The person is a woman in her 50s from Middlesex County and she was never hospitalized for her illness, according to the DPH. Three other cases were reported on Friday.

Investigations conducted by state public health officials indicate that at least two of the four cases were exposed in the greater Boston area leading them to raise the risk level from moderate to high for 11 communities in the area. Those communities are Arlington, Boston, Belmont, Brookline, Cambridge, Chelsea, Everett, Medford, Newton, Somerville, and Watertown, according to the state agency.

“Several individuals from the same area have developed West Nile virus,” said Public Health Commissioner Monica Bharel. “That means that there is an increased risk in this specific area and that additional people could become infected. We are particularly concerned about people over 50 and those who are immunocompromised as they are the ones most likely to develop WNV disease.”

On Aug. 21, the DPH raised the risk level for West Nile virus from low to moderate in every Massachusetts city and town. It was only the second time since WNV was first detected in the Commonwealth in 2000 that public health officials have raised the risk level statewide.

The West Nile virus has been detected in mosquitoes throughout the MetroWest region.

In 2017, there were six human cases of WNV infection identified in Massachusetts.

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. When present, WNV symptoms tend to include fever and flu-like illness. In rare cases, more severe illness can occur.