WEST NILE VIRUS IS AN INSECT-BORNE DISEASE THAT CAN ONLY BE TRANSMITTED TO PEOPLE BY THE BITE OF AN INFECTED MOSQUITO. MOST WEST NILE INFECTIONS ARE SO MILD THAT THE VAST MAJORITY OF VICTIMS MISTAKE THEIR SYMPTOMS-FEVER, HEADACHE, SKIN RASH, SWOLLEN LYMPH GLANDS-FOR FLU OR COLD. LESS THAN 1% OF INFECTED PEOPLE DEVELOP LIFE-THREATENING CONDITIONS LIKE MENINGITIS OR ENCEPHALITIS.

view West Nile virus fact sheet (MDPH)

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.

A hot, rainy summer allowed mosquito populations in Massachusetts to flourish. The increased mosquito population, in turn, has helped West Nile virus become more widespread in the region than in 2007 and 2006. Within the Commonwealth, the risk for human infection may be highest in the Boston, Worcester, and Springfield metropolitan areas because these regions currently have more elevated levels of West Nile virus activity among birds and mosquitoes.

"Even though temperatures have dipped, we continue to see infected EEE and WNV mosquitoes," said Dr. Al DeMaria, an epidemiologist at the Massachusetts Department of Public Health, in a Sept. 23 statement. "The risk of EEE and WNV will be greatly reduced once we see the first hard frost and the mosquito population dies off. Until then, we urge the public to continue to use mosquito repellent."

As of September 29, West Nile virus had been detected in 63 dead birds and 131 mosquito pools in 88 Massachusetts communities including Boston, Brookline, Dedham, Lexington, Lynn, Malden, Medford, Milton, Natick, Newton, Quincy, Revere, Salem, Somerville, Waltham, Watertown, and Winchester.

No Massachusetts residents have been diagnosed with West Nile virus this year to date. In 2007, six Massachusetts residents were infected with the virus. Remember, the greatest risk of infection is between mid-August and early October (until the first frost).

Since mosquitoes lay their eggs in still water, residents can help reduce mosquito breeding places on their property by:

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

If you can't get rid of standing water by sweeping or other methods, please report the address or approximate 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

For more ideas on how to protect yourself from West Nile virus and other mosquito-borne diseases, see the health department's prevention tips.

For general information, visit the Massachusetts Department of Public Health arbovirus website.

Posted on October 2, 2008