2 diagnosed with West Nile virus

A 53-year-old Arlington man and a 48-year-old Worcester woman have been diagnosed with West Nile virus, the first known cases of the mosquito-borne illness contracted in Massachusetts this year, health authorities said today.

Both the man and the woman became sick in August, and both are now at home recovering, said Donna Rheaume, a spokeswoman for the state Department of Public Health.

Three other people were diagnosed earlier in the summer with West Nile while in Massachusetts, but in two cases, the patients were visitors who had been infected in their home state. The third case involved a Boston man exposed to the virus while outside of Massachusetts.

So far this year, nearly 1,400 cases of West Nile have been documented in the United States, with most reported from states west of the Mississippi River.

In the most severe cases, West Nile virus can cause a high fever, headache, neck stiffness, stupor, coma, tremors, convulsions, muscle weakness, and paralysis. The US Centers for Disease Control and Prevention estimates that one of every 150 people infected with West Nile develops severe symptoms.

To avoid contact with infected mosquitoes, the Massachusetts Department of Public Health recommends limiting outdoor activities from dusk to dawn, peak biting times for mosquitoes. Otherwise, wear as much clothing as comfortable and apply insect repellent such as DEET, permethrin, picaridin, or oil of lemon eucalyptus.

DEET should not be used on infants under the age of 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 under 3 years old.