West Nile makes seasonal arrival in Massachusetts

By Stephen Smith, Globe Staff

For the first time this summer, disease trackers in Massachusetts have discovered mosquitoes carrying West Nile virus, health authorities reported this afternoon. The mosquitoes were collected Tuesday in the town of Walpole in Norfolk County.

Earlier this week, the first mosquitoes carrying another viral illness, Eastern equine encephalitis, were identified in Freetown.

No human cases of West Nile or Eastern equine have been reported so far in Massachusetts.

During the past five years, 16 people in the state have been diagnosed with West Nile. Federal disease specialists estimate that about one of every five people infected with the virus develop symptoms, including fever, headache, fatigue, and body aches; occasionally, patients develop rashes and swollen lymph glands. In the most severe cases, patients can become disoriented, descend into comas, and even die.

To avoid being bitten by a mosquito, specialists recommend staying inside from dusk to dawn, peak mosquito-biting time. If outdoor activity is necessary at night, wear long sleeves, long pants, and socks. Bug repellants such as DEET, permethrin, picaridin, and oil of lemon eucalyptus also can provide protection. DEET should not be used on infants younger than 2 months and should be used in concentrations of 30 percent or less on older children. Oil of lemon eucalyptus should not be used on children younger than 3 years.

Homeowners can take measures that reduce mosquitoes' breeding grounds, including draining flower pots, wading pools, and gutters.