About West Nile Virus

No mosquito samples in Somerville have tested positive for the virus so far this year, but Massachusetts health officials have detected the presence of the virus in a mosquito sample taken from Weymouth on June 20, 2018.

Helpful suggestions are below, and now is the season to make these precautions part of your outdoor routine. Late July through September is usually the period of greatest West Nile Virus activity in Massachusetts.

What can you do to prevent mosquito-borne illness?

Avoid Mosquito Bites

  • Apply Insect Repellent when Outdoors:
    Use a repellent with DEET, oil of lemon eucalyptus 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.
  • Wear Clothing that will cover your body:
    Wearing long-sleeves, long pants and socks when outdoors will help keep mosquitoes away from your skin, which can prevent mosquito bites. If it’s hot, consider light, loose and breathable clothing that covers you but still allows you to keep cool.  If you’ll be out all day into the evening, bring layers or at least a light throw, so you can cover up after dusk.
  • Wear light-colored clothing and avoid fragrances:
    Mosquitoes see dark colors like blue and black more easily than light colors like tan and white, meaning that dark clothes make you an easy target. So choose light-colored clothing when outdoors. Likewise, fragrances attract mosquitoes. So it’s best to avoid perfumes and scented products when heading outdoors.

Reduce Mosquito Breeding Areas

Mosquitoes lay their eggs in still or stagnant water found in catch basins, roof gutters clogged with leaves, old tires, flower pots, bird baths, swimming pool covers, buckets, cans, barrels, and other places where water can be trapped. You can greatly reduce the city's mosquito population by removing mosquito breeding areas on your property. 

  • Empty, treat, or refresh any outdoor items that hold water:
    • Remove or treat standing water in flower pots, swimming pool covers, buckets, cans, barrels, or persistent puddles. 
    • Do not leave water bowls outside for your animals when they are inside; empty the bowl when not being used.
    • If you have intentional standing water, such as in bird baths or rain barrels, change/use up the water at least every three to five days to prevent mosquito larvae from hatching.
    • Empty and clean kiddie pools daily after use (both for your children’s safety and to prevent mosquitoes).
    • Consider treating standing water that is not eliminated, such as in flower pot saucers, rain barrels, or ditches with wildlife-safe mosquito dunks.
    • Clean rain gutters, leaves in downspouts, and pooled water on flat roofs.  Remember to use caution when you clean out these items.
    • Remove containers that may hold water in places that are hard to see, such as under bushes, porches, decks, or stairs.
    • Repair any leaky outdoor faucets or hoses.

Learn About Mosquito-borne Illness

  • What is Mosquito-borne illness? 
    Mosquito-borne illness is spread by the bite of an infected mosquito. In the Northeastern United States, it is usually caused by viruses such as West Nile Virus or Eastern Equine Encephalitis virus.
  • How common is mosquito-borne illness?
    There is a low risk of infection following a mosquito bite. Most people bitten by infected mosquitoes experience no illness or only mild illness, but a small number of people can develop a more serious disease.
  • How is it spread?
    Mosquito-borne illness is spread to people through the bite of an infected mosquito.
  • When is it spread?
    The time of the year when mosquitoes are most active and most likely to carry disease is between late July and late September, but if the weather remains warm, the risk period can extend as late as November. The time of day when mosquitoes are most active is at night, dusk and dawn, but you can be bitten at any time.
  • Am I at risk?
    People at higher risk for developing serious symptoms from WNV are those over age 50, however Eastern Equine Encephalitis can cause serious illness in any age group.
  • What should I do if I get bitten by a mosquito?
    Mosquito-borne illness is very rare in Somerville. So your risk following a mosquito bite is small. However, you should see your doctor immediately if you develop high fever, confusion, severe headache, stiff neck, or if your eyes become sensitive to light.