The Massachusetts Department of Public Health [DPH] announced the first detection of West Nile virus [WNV] in Massachusetts in 2021.
The detection of WNV was in a mosquito sample collected on June 29, in the town of Medford in Middlesex County.
There are no human or animal cases of WNV or Eastern Equine Encephalitis [EEE] detected so far this year. There is no elevated risk level or risk-level change associated with this finding.
Human cases of WNV typically transmit through the bit of an infected mosquito. In 2020, DPH announced eight human cases of WNV detected in Massachusetts. The highest number of cases detected in Massachusetts was in 2018, with 49 cases detected.
People over the age of 50 are at the highest risk of WNV, though people of all ages can contract the virus. WNV symptoms include fever and flu-like illness. In rare cases, severe illness can occur. In most cases, an infected person will have no symptoms.
Tips to Avoid Exposure to WNV
The Department of Public Health offers some guidance for residents to avoid exposure to WNV.
Avoid Mosquito Bites
- When outdoors, apply Insect Repellent with an EPA-registered ingredient (DEET (N, N-diethyl-m-toluamide), permethrin, picaridin (KBR 3023), oil of lemon eucalyptus [p-methane 3, 8-diol (PMD)] or IR3535) according to the product label instructions.
- 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.
Wear Appropriate Clothing to 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 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 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 WNV and Eastern Equine Encephalitis [EEE].
- If an animal is suspected of having WNV or EEE, owners are required to report this 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.