August 04, 2022

Risk of West Nile Virus Infection Raised to Moderate in Cambridge and Nearby Communities

August 4, 2022

On August 4, the Massachusetts Department of Public Health raised the risk of West Nile virus infection from “low” to “moderate” in Cambridge and eight other communities: Arlington, Belmont, Boston,  Brookline, Newton, Somerville,  Waltham, and Watertown. The rest of the state is currently at low risk.  

No mosquito samples have tested positive for West Nile virus in Cambridge so far this summer, but positive mosquitoes have been detected in these nearby communities: Boston, Brookline, Somerville, and Waltham.

The virus is usually transmitted to humans through the bite of an infected mosquito. Most human West Nile virus infections are mild, but a small number of people—fewer than 1% of those infected—become very sick. People over 50 are at greatest risk for serious illness, especially those with weakened immune systems.

No human cases of West Nile virus have been reported so far this season in Massachusetts. 

The best way to avoid West Nile virus is to prevent mosquito bites. Some tips:

  • Apply insect repellent when outdoors. Use a repellent with DEET, permethrin, picaridin, oil of lemon eucalyptus or IR3535. 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. Follow the directions on the package.
  • 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.
  • Clothing can help reduce mosquito bites. Wearing long-sleeves, long pants, and socks when outdoors will help keep mosquitoes away from your skin.
  • Get rid of mosquito breeding sites in your yard. Mosquitoes lay their eggs in still water. Empty standing water from flower pots, buckets, barrels, tires, and children’s pools. Change the water in pet dishes, and replace the water in bird baths weekly. Drill holes in tire swings so water drains out.
  • Make sure that window and door screens fit tightly and are in good condition.

State and county information about West Nile virus and reports of West Nile virus activity in Massachusetts can be found on the state health department website. For local West Nile virus updates and prevention tips, call the Cambridge Public Health Department at 617-665-3838 or visit the department’s Mosquito-borne Diseases page.