There have been four human cases of the West Nile virus in Massachusetts this year, prompting risk levels to increase to high for more than 25 communities in Essex, Middlesex, Norfolk and Suffolk counties.
All four individuals were likely exposed to the virus in Middlesex County, the state Department of Public Health has said. Two are men, one in his 50s and the other in his 70s, and two are women, one in her 70s and the other in her 80s.
With an increase in WNV activity, the risk of the virus is now considered high -- meaning more people may get infected with West Nile in the area -- in the following 27 communities: Arlington, Bedford, Belmont, Boston, Brookline, Burlington, Cambridge, Chelsea, Everett, Lexington, Lincoln, Lynnfield, Malden, Medford, Melrose, Newton, Reading, Revere, Saugus, Somerville, Stoneham, Wakefield, Waltham, Watertown, Winchester, Winthrop, and Woburn.
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West Nile virus is usually transmitted to humans through the bite of an infected mosquito. It can infect people of all ages, though people over the age of 50 are at higher risk for severe disease. Most people infected with the virus have no symptoms. When present, symptoms include fever and flu-like illness. In rare cases, more severe illness can occur.
There have been no deaths this year associated with the virus.
Health officials are reminding Bay State residents that they play an important role in protecting themselves from mosquito-borne illnesses.
The DPH advises people over 50 or those who are immune compromised to adjust their outdoor activity to avoid peak mosquito hours (from dusk to dawn) in high-risk communities in the commonwealth, and everyone should avoid mosquito bites by applying insect repellent (with DEET) and wearing long clothing.
More information, including all West Nile virus and EEE positive results can be found on the state's website or by calling the DPH Epidemiology Program at 617-983-6800.