Eastern equine virus found in Massachusetts

By Stephen Smith, Globe staff

For the first time this summer, mosquitoes carrying eastern equine encephalitis have been discovered in Massachusetts, state public health authorities announced this afternoon.

The infected insects were found in Carver. There have been no human cases so far this year in the state. The risk of catching Eastern Equine this summer appears relatively low, in part because the virus is making a late debut in the state. Last year, for example, eastern equine was first detected in early July.

From 2004 through 2006, 13 people contracted the mosquito-borne illness, resulting in six deaths. Eastern equine encephalitis is known to be highly lethal, killing up to half of people who fall ill from the virus.

Disease trackers from the state Department of Public Health also reported today that West Nile virus, another disease spread by mosquitoes, has continued to migrate across the state. During the past week, crows carrying the virus with have been found in Belchertown, Worcester, Hingham, Plymouth, and Barnstable, while infected mosquitoes were identified in Boston, Brookline, Needham, Weymouth, Dedham, Brockton, Dartmouth, Worcester and Medford.

No human cases of West Nile have reported in Massachusetts this year. Last year, six Bay Staters contracted the ailment.

To avoid being bitten, public health authorities recommend avoid being outside from dusk to dawn, peak time for mosquito activity. If outdoor activity is necessary during those hours, long-sleeved shirts, long pants, and socks can provide protection. Repellants can help, too, including DEET, permethrin, picaridin, or oil of lemon eucalyptus. DEET should not be used on babies 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 under the age of 3 years.

Draining standing water from gutters, unused flower pots, and wading pools can deprive mosquitoes of necessary breeding grounds. And having secure window screens can prevent the bugs from getting inside homes.

Most people infected with West Nile never experience symptoms. However, about one in five who contract the virus, usually spread by mosquitoes, develop symptoms that include a fever, headache, body aches, nausea, and vomiting; some of them also experience swollen lymph glands or rash on the chest, stomach, and back.

In the rarest cases, affecting about one out of every 150 people infected with the virus, severe symptoms develop, including high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness, and paralysis. Those symptoms can last several weeks and may lead to permanent neurological damage and death.