- Department of Public Health
Media Contact
Katheleen Conti, Assistant Director of Media Relations
Boston — The Massachusetts Department of Public Health (DPH) today announced the season’s ninth human case of West Nile virus (WNV) diagnosed in a man in his 50s with exposure in Middlesex County.
No risk level increases are indicated at this time of year. At the end of October, municipalities at high risk for WNV will be reduced to moderate until there is a hard frost.
“This case is a reminder that WNV infections can occur even in the fall, and we should remain vigilant,” said Public Health Commissioner Robbie Goldstein, MD, PhD. “We are now past the peak season for West Nile virus in Massachusetts, but some risk will continue until the first hard frost, and we are still reminding everyone to continue to take steps to protect themselves from mosquito bites.”
The first WNV-positive mosquitoes in the state this year were announced on June 17. There were a total of 451 mosquito samples that tested positive for WNV this season from Barnstable, Berkshire, Bristol, Dukes, Essex, Franklin, Hampden, Middlesex, Norfolk, Plymouth, Suffolk, and Worcester counties. There was also one animal case of WNV this year in a goat.
In addition to WNV, Eastern equine encephalitis (EEE) was detected in mosquitoes in Massachusetts this year. There were 23 EEE-positive mosquito samples and no human or animal cases.
Surveillance information, including case updates, will continue to be updated as needed and posted online at the Massachusetts Arbovirus Update.
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 the 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 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.
Learn more about mosquito-borne diseases, including all WNV- and EEE-positive results on DPH’s Arbovirus Surveillance Information page, which is updated daily, or by calling the DPH Division of Epidemiology at 617-983-6800.