Four more cases of West Nile Virus have been confirmed in Massachusetts, according to state Department of Health Officials.
The four cases, found in Middlesex and Hampden County residents, were listed as probable earlier in the week.
The West Nile Virus threat level was raised to "high" in Chelsea, Chicopee, Everett, Lexington, Malden, Melrose, Revere, Saugus and Winthrop in response to the cases. The threat level was raised to "moderate" in Bedford, Burlington, Holyoke, Lincoln, South Hadley, Stoneham, Wakefield, West Springfield, Winchester and Woburn.
West Nile-infected mosquitos have been found in 97 communities in Massachusetts this summer. Officials said the state likely hasn't seen as many West Nile-infected mosquito pools in the state since 2000.
Officials said most people infected with the virus do not exhibit any symptoms, but fever and flu-like symptoms can be associated with it.
A total of eight people had been infected with West Nile Virus in Massachusetts in 2012.
