Wednesday, Sept. 4, 2024

State health officials announce two additional human cases of West Nile Virus

WNV risk levels elevated in multiple communities

For immediate release: 9/3/24

BOSTON – The Massachusetts Department of Public Health (DPH) today announced two additional human cases of West Nile virus (WNV) in Massachusetts this year, bringing the total number of human cases to six. One is a man in his 50s who was exposed in Suffolk County; the other is a man in his 80s with exposure in southern Middlesex County.As a result, WNV risk levels in the following area communities are being raised to high: Saugus in Essex County; Arlington, Belmont, Malden, Medford, and Melrose in Middlesex County; and Chelsea, Revere, and Winthrop in Suffolk County.

“The risk of West Nile virus in Massachusetts will continue until the first hard frost. While the temperatures may be a bit cooler, September is still within the peak time for West Nile virus activity in Massachusetts,” said Public Health Commissioner Robbie Goldstein, MD, PhD. “As we all adjust to our post-summer schedules, one routine that everyone should continue is using mosquito repellent when outdoors.”

There have been 286 WNV-positive mosquito samples so far this year detected from Barnstable, Berkshire, Bristol, Dukes, Essex, Hampden, Middlesex, Norfolk, Plymouth, Suffolk, and Worcester counties. The risk of human infection with WNV is moderate or high in Greater Boston (Middlesex, Norfolk, and Suffolk counties) and is also elevated in parts of Barnstable, Bristol, Essex, Hampden, Plymouth, and Worcester counties.

WNV is usually transmitted to humans through the bite of an infected mosquito. There were six human cases of WNV and no animal cases in 2023. No animal cases of WNV have been detected so far this year.

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 an EPA-registered ingredient, such as DEET (N,N-diethyl-m-toluamide), permethrin, picaridin (KBR 3023), or oil of lemon eucalyptus (p-menthane-3,8-diol (PMD) or IR3535) according to the instructions on the product label. DEET products should not be used on infants under two months of age and should be used in concentrations of 30 percent 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 in areas of high risk.

Clothing Can Help Reduce Mosquito Bites. Wearing long sleeves, long pants and socks when outdoors will 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 draining or discarding items that hold water. Check rain gutters and drains. Empty 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 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 provide excellent mosquito breeding habitats and should be flushed out at least once a week during the summer months 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 West Nile virus (WNV) and EEE. If an animal is suspected of having WNV or EEE, owners are required to report to the Department of Agricultural Resources, Division of Animal Health by calling 617-626-1795, and to the Department of Public Health by calling 617-983-6800.

More information, including all WNV and EEE positive results, can be found on the Arbovirus Surveillance Information web page at Mosquito-borne Diseases | Mass.gov, which is updated daily, or by calling the DPH Division of Epidemiology at 617-983-6800.