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 mosquito pool that tested positive for West Nile virus was collected on Meadow Way (just north of Mount Auburn Cemetery) in Cambridge on Sept. 8. State health officials reported on Sept. 18 that a dead blue jay found on the Watertown side of Mount Auburn Cemetery had tested positive for West Nile virus. In addition, a positive mosquito pool was collected on the Watertown side of the cemetery on Aug. 29.

On Sept. 17, the state announced that a 53-year-old man from Arlington and a 48-year-old woman from Worcester had both been diagnosed with West Nile virus. Both people became ill in August. These are the first cases of West Nile virus contracted in the Commonwealth this year. (State health officials had previously identified three additional human cases, but believe the infections were acquired out-of-state.)

"The discovery of the West Nile virus-positive pools near the cemetery is not surprising," said Sam Lipson, the director of environmental health for the Cambridge Public Health Department, noting that infected mosquitoes have also been found in Belmont, Medford, Boston, Brookline, and Newton.

Lipson believes the risk of West Nile virus infection is reduced this year because of the lack of rainfall in August. "As a result of the late summer drought, the mosquito population in the Boston area has been relatively small, and the overall risk to the public from this mosquito-borne virus isn't considered to be significant," he said.

Lipson added that despite the two human cases, "there is only a slight chance that a person would be bitten by an infected mosquito, and then a very small chance that such a bite would result in serious illness."

Nonetheless, Lipson cautioned residents who spend time outdoors, especially those age 50 or older, to wear long-sleeved clothing or use mosquito repellent.

This year, West Nile virus has been detected in birds and mosquitoes in 42 Massachusetts communities including: Cambridge, Watertown, Belmont, Medford, Boston, Revere, Brookline, Newton, Salem, Marblehead, Manchester, North Reading, and Swampscott. In total, 36 birds and 52 mosquito pools in Massachusetts have tested positive for the virus this year (as of Sept. 17).

For more ideas on how to protect you and the community from West Nile virus, see the Cambridge Public Health Department's prevention tips.