Cambridge Mosquito Sample Tests Positive for West Nile Virus

State health officials reported on July 9 that a mosquito sample in Cambridge had tested positive for West Nile virus. The virus is usually transmitted to humans through the bite of an infected mosquito. People do not become infected by having direct contact with other infected people, birds, or animals.

Most human West Nile virus infections are mild, but a small number of people 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. Learn more about West Nile virus from the state’s website.

The risk of West Nile virus infection in Cambridge remains “low,” according to the Massachusetts Department of Public Health. Low risk means an infection of West Nile virus is unlikely.

Although the risk level has not gone up, the Cambridge Public Health Department wants to remind Cambridge residents to take precautions in avoiding mosquito bites as it is the best way to prevent West Nile virus.

There are simple things residents can do to prevent mosquito bites:

• 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. While the hours from dusk to dawn are peak biting times for many mosquitoes, some are still active during the day. It’s best to wear repellent during the day as well as night.

• Wear long-sleeved clothing to help keep mosquitoes away from your skin.
  
• Repair damaged window and door screens.
  
• Get rid of standing water in your yard. Mosquitoes lay their eggs in still water. Empty standing water from flower pots, buckets, barrels, and children’s pools. Drill holes in tire swings so water drains out.
  
• Buy mosquito dunk. It is a natural bacterium sold in hardware stores. These tablets can be added to stagnant water that cannot be emptied easily such as rain barrels or small pools of water, and they do not harm people nor beneficial pollinators (bees, butterflies, beetles, and many other insects).

You can learn more about mosquito bite prevention, as well as what the Cambridge Public Health Department and the City of Cambridge do to reduce the risk, by visiting the health department’s Mosquito-borne Diseases web page.

You can also view reports about West Nile virus activity in Massachusetts on the state health department’s website.