- Department of Public Health
Media Contact for State health officials announce season’s first human case of West Nile virus in Massachusetts
Katheleen Conti, Assistant Director of Media Relations
Boston — The Massachusetts Department of Public Health (DPH) today announced the first human case of West Nile virus (WNV) in the state this year. The individual is a female in her 80s who was likely exposed to the virus in Middlesex County, an area known to be at moderate risk. The risk of human infection with WNV is moderate in the Greater Boston area, and several towns in Bristol and Worcester counties. There are no risk level changes associated with this finding; there have been no deaths this year associated with WNV.
“This is the first time that West Nile virus infection has been identified in a person in Massachusetts this year,” said Acting Public Health Commissioner Margret Cooke. “Risk from West Nile virus has been slow to increase this year. This is an important reminder that we all need to continue to take steps to protect ourselves and our families from mosquito bites.”
Although late in the season, the substantial amount of rain in the region in July and the recent hot weather have resulted in an increase in the population of the Culex species of mosquitoes, known to spread West Nile virus and breed in places where standing water accumulates.
In 2020, there were 11 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 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% 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 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 WNV and Eastern Equine Encephalitis (EEE). If an animal is diagnosed with WNV or EEE, owners are required to report to DAR, Division of Animal Health by calling 617-626-1795 and to the Department of Public Health (DPH) 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 www.mass.gov/dph/mosquito or by calling the DPH Epidemiology Program at 617-983-6800.