Mass. announces first 2 human cases of West Nile virus this year

Two Massachusetts residents have contracted West Nile virus in the state's first human cases this year.

One woman in her 70s was exposed to the mosquito-borne virus in another area of the country, the Massachusetts Department of Public Health said Tuesday. A man in his 40s was exposed in Middlesex County, which health officials had deemed to be at moderate risk.

The DPH notes that the risk of human infection is considered moderate in Middlesex County, Norfolk County and Suffolk County, as well as in parts of Bristol County, Plymouth County, Worcester County, Hampden County, Hampshire County and Berkshire County.

The risk level for the far deadlier Eastern Equine Encephalitis, or EEE — also spread by mosquitoes — is considered remote to low across the state, data from the DPH shows. Of 12 people infected in 2019, six died.

By contrast, about 80% of people infected with West Nile virus do not experience symptoms — which can include fever, headaches, body aches, nausea, vomiting, swollen lymph nodes and rashes, according to the state. Under 1% of infected people develop severe illness.

"This is the first time that West Nile virus infection has been identified in Massachusetts residents this year," Public Health Commissioner Robert Goldstein said in a statement. "August and September are the months when most people are exposed to West Nile virus in Massachusetts."

Eight human cases of West Nile virus were identified last year, the first of which was announced on Aug. 25. The first case of 2021 came on Sept. 1.

"Populations of mosquitoes that can carry and spread this virus are fairly large this year and we have seen recent increases in the number of WNV-positive mosquito samples from multiple parts of the Commonwealth," Goldstein's statement added.

Protect yourself from West Nile Virus

• Avoid mosquito bites: Apply insect repellent when outdoors and use a repellent that contains DEET (except on infants under two months of age, and not in concentrations higher than 30% on older children).
• Be aware of peak mosquito hours: The hours from dusk to dawn are peak biting times for many mosquitoes.
• Wear long clothing: Long sleeves, long pants and socks when outdoors can help keep mosquitoes away from your skin.
• Mosquito-proof your home: Drain standing water, which is where mosquitoes lay eggs. Drain or discard items around your home that hold water. Check rain gutters and drains. Empty unused flowerpots and wading pools. Install or repair screens on all of your windows and doors in order to have tightly-fitting screens that keep mosquitoes outside.
• Protect your animals: Owners should speak with their veterinarian about mosquito repellents approved for use in animals and vaccinations to prevent WNV and Eastern Equine Encephalitis. If an animal is diagnosed with WNV or EEE, owners are required to report to the Massachusetts Department of Agricultural Resources’ Division of Animal Health by calling 617-626-1795 and to the DPH by calling 617-983-6800.

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.