Risk level raised as woman infected with West Nile Virus in Bristol County

BOSTON (September 16, 2021) – The Massachusetts Department of Public Health today announced an additional case of West Nile virus in the state this year. WNV infection was identified in a woman in her 30s who was exposed to WNV in Bristol County. This is the seventh human case of WNV this year.

Previously, since September 1, DPH has announced six human cases and one animal case of WNV in Massachusetts. Twenty-seven communities in Essex, Middlesex, Brookline and Suffolk counties are at high risk and forty-nine communities are at moderate risk. Based on mosquito findings and the new human case, eleven additional communities are being raised to moderate risk. Those communities are: Fall River and Seekonk in Bristol County; North Andover in Essex County; Bridgewater, East Bridgewater, Halifax, and Plympton in Plymouth County; and Blackstone, Hopedale, Milford, and Millville in Worcester County. As overnight temperatures get cooler, mosquito activity right around dusk and dawn may be more intense.

“This is our first West Nile virus case this year in someone under the age of 50,” said Acting Public Health Commissioner Margret Cooke. “This is a reminder that although people over the age of 50 are at greater risk from West Nile virus, all ages can be affected. Risk from West Nile virus will continue until the first hard frost and people should remember to take steps to prevent mosquito bites anytime they are outdoors.”

In 2020, there were five human cases of WNV infection identified in Massachusetts.

WNV is usually transmitted to humans through the bite of an infected mosquito. While WNV can infect people of all ages, people over the age of 50 are at higher risk for severe disease. Most people infected with WNV will have no symptoms. When present, WNV symptoms tend to include fever and flu-like illness. In rare cases, more severe illness can occur.

People have an important role to play in protecting themselves and their loved ones from illnesses caused by mosquitoes.

Avoid Mosquito Bites

Apply Insect Repellent when Outdoors. Use a repellent with DEET (N, N-diethyl-m-toluamide), permethrin, picaridin (KBR 3023), oil of lemon eucalyptus [p-menthane 3, 8-diol (PMD)], or IR3535 according to the product label. DEET products should not be used on infants under two months of age and should be used in concentrations of 30% or less on older children. Oil of lemon eucalyptus should not be used on children under three years of age.

Be Aware of Peak Mosquito Hours. The hours from dusk to dawn are peak biting times for many mosquitoes. Consider rescheduling outdoor activities that occur during evening or early morning.

Clothing Can Help Reduce Mosquito Bites. Wear long-sleeves, long pants, and socks when outdoors to help keep mosquitoes away from your skin.

Mosquito-Proof Your Home

Drain Standing Water. Mosquitoes lay their eggs in standing water. Limit the number of places around your home for mosquitoes to breed by either draining or discarding items that hold water. Check rain gutters and drains. Empty any unused flowerpots and wading pools, and change the water in birdbaths frequently.

Install or Repair Screens. Keep mosquitoes outside by having tightly fitting screens on all of your windows and doors.

Protect Your Animals

Animal owners should reduce potential mosquito breeding sites on their property by eliminating standing water from containers such as buckets, tires, and wading pools – especially after heavy rains. Water troughs should be flushed out to reduce mosquitoes near paddock areas. Horse owners should keep horses in indoor stalls at night to reduce their risk of exposure to mosquitoes. Owners should also 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.