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Event title

United States - West Nile virus risk raised to high in 27 Mass. communities

Event category

Biological origin - Infection hazard



Event date (UTC)

2021-09-13 04:08:11

Last update (UTC)

2021-09-13 04:08:12





Area range

Multiple counties wide event

Address/Affected area(s)


The Massachusetts Department of Public Health announced an increased high risk of West Nile virus infection in 27 towns, after the discovery of four human cases and one animal case. “Based on the occurrence of both animal and human cases, above-average populations of the Culex mosquitoes that carry [West Nile virus], recent rainfall, and continued weather favorable for mosquito activity, the WNV risk level is being raised in 27 communities from moderate to high,” the state wrote in a statement on Friday. The four human cases — the first cases of the year in Massachusetts — were announced last week. An alpaca in Middlesex County was also diagnosed with WNV, according to the statement. The WNV risk increased from moderate to high risk in 27 different communities across four counties. The state also created a map highlighting the affected areas. The towns include Lynnfield and Saugus, in Essex County; Arlington, Bedford, Belmont, Burlington, Cambridge, Everett, Lexington, Lincoln, Malden, Medford, Melrose, Newton, Reading, Somerville, Stoneham, Wakefield, Waltham, Watertown, Winchester, and Woburn in Middlesex County; Brookline in Norfolk County; and Boston, Chelsea, Revere, and Winthrop in Suffolk County. WNV, which is typically contracted by humans and animals from mosquito bites, can give people flu-like symptoms and severe illness in rare cases. However, the department wrote many people do not get any symptoms. “September is the month when we are most likely to see people get infected with West Nile virus,” acting Public Health Commissioner Margret Cooke said in a statement. “While we advise everyone to take steps to avoid mosquito bites, this is especially important if you are over the age of 50 or have an immune compromising condition. It is also important to know that as overnight temperatures get cooler, mosquito activity right around dusk and dawn may be more intense.”
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