A Halifax man in his 90s has contracted Eastern Equine Encephalitis, the third human case of the mosquito-borne virus in Massachusetts this year, officials confirmed.

EEE is a rare but serious and potentially fatal disease that can affect people of all ages. Last year was the most active in decades for the virus, with 12 human cases of EEE and six deaths across Massachusetts. Public health officials expect 2020 to be another active year since outbreaks tend to occur in two-to-three-year cycles.

This week the state's Department of Public Health elevated the EEE risk level in Halifax to "critical" and upped the risk levels in East Bridgewater and Hanson to "high" based upon tests showing the presence of infected mosquitos.

Statewide, there are now four municipalities with a critical risk label. They are Halifax, Carver, Middleborough and Wilbraham. Nine more are deemed high-risk communities. They are Bridgewater, East Bridgewater, Monson, Hampden, Hanson, Kingston, Plympton, Rochester and Wareham. The state provides a map showing the current risk level in each community.

The DPH said people across Massachusetts should take steps to avoid being bitten by mosquitos. They recommend that people use mosquito repellents with an EPA-registered active ingredient, wear long sleeves and long pants when outdoors, dump any standing water on their property, and remain aware of the presence of mosquitos.

Gov. Charlie Baker in July signed a new law that gives the State Reclamation and Mosquito Control Board greater powers when the DPH determines there is an elevated risk. Spraying for mosquitos was conducted earlier this month in the pre-dawn hours in certain communities.

The 25 communities in the spray zone are Bridgewater, Carver, Duxbury, East Bridgewater, Halifax, Hanover, Hanson, Kingston, Lakeville, Marion, Mattapoisett, Middleborough, Norwell, Pembroke, Plymouth, Plympton, Rochester, Rockland, Wareham, West Bridgewater, and Whitman in Plymouth County, and Acushnet, Easton, Raynham, and Taunton in Bristol County. The spray zone map is available online.

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