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West Nile Virus

The Cambridge Public Health Department leads the city's response to the risks posed by West Nile virus, eastern equine encephalitis, and other mosquito-borne diseases.

WEST NILE VIRUS UPDATE:  October 19, 2015
On Oct. 16, state health officials announced that a Suffolk County woman in her 30s tested positive for West Nile virus, but was not hospitalized. Nine Massachusetts residents have been diagnosed with West Nile virus this year, including two Suffolk County residents who died from the disease.

In 2015, WNV-infected mosquitoes were detected in the following Greater Boston communities: Arlington, Bedford, Belmont, Boston, Brookline, Burlington, Cambridge, Chelsea, Everett, Lexington, Lowell, Malden, Medford, Melrose, Natick, Newton, Quincy, Reading, Revere, Somerville, Wakefield, Waltham, Watertown, Wellesley, Wilmington, and Winthrop.

A total of seven mosquito samples in Cambridge tested positive for the virus this year.

What is the current risk?

Due to the hard frost that occured between Oct. 17-19, the risk of West Nile virus infection in Cambridge and most (if not all) of Massachusetts is negligible. However, people who were bitten by mosquitoes in late September or earlier in October remain at risk for developing West Nile virus infection.

To learn more about risk of West Nile virus in Cambridge and the state, see the risk map from the Massachusetts Department of Public Health.


Avoid Mosquito Bites

  • Apply Insect Repellent when Outdoors. Use a repellent with 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 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.
  • Clothing Can Help Reduce Mosquito Bites. Wearing long-sleeves, long pants and socks when outdoors will help keep mosquitoes away from your skin.
  • For more information on how to protect yourself, see the Cambridge Public Health Department's Prevention Tips.

Reduce Mosquito Breeding Areas

In New England, the mosquitoes that carry West Nile virus are "container breeding" species.  These 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. Tenants, property managers, and homeowners can greatly reduce the city's mosquito population by removing mosquito breeding areas on their property.

Remove stagnant water from your property

  • Empty or treat any items that hold water, such as flower pots, birdbaths, swimming pool covers, buckets, cans, and barrels.
  • Clean rain gutters, leaves in downspouts, and pooled water on flat roofs.
  • Remove unused tires and other items that could collect water.
  • Remove containers that may hold water in places that are hard to see, such as under bushes, porches, decks, or stairs.

When you can't get rid of stagnant water by sweeping or other methods (such as Mosquito Dunk, a product sold in hardware stores), please report the address or location of the puddle or still water source to the appropriate city department:

  • Private property: Cambridge Public Health Department, 617-665-3848
  • Public property (roads, parks): Cambridge Dept. of Public Works, 617-349-4800
  • Construction sites: Cambridge Inspectional Services, 617-349-6100

If you have questions or local concerns about West Nile virus or stagnant water, please contact the Cambridge Public Health Department’s Environmental Health Division at 617-665-3848 or contact Environmental Health staff at ksasportas@challiance.org.

For general information, visit the Massachusetts Department of Public Health's arbovirus website and the CDC's West Nile virus website.

Last updated on October 19, 2015

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Cambridge Health Alliance | City of Cambridge
Cambridge Public Health Department
119 Windsor Street, Ground Level, Cambridge, MA 02139
Tel: 617.665.3800   Fax: 617.665.3888