CAMBRIDGE, Mass. — Massachusetts health officials say a Cambridge resident in his 70s has been hospitalized with the state’s second human case of West Nile virus this year.
Thursday’s announcement came just over a week after another Middlesex County man, in his 60s, was reported with the first case of the mosquito-borne virus, which can develop into encephalitis, an inflammation of the brain, and be fatal. Young people, old people and those with compromised immune systems are particularly vulnerable.
The Department of Public Health raised the virus threat level to “high,” meaning multiple cases are very likely, in Cambridge and the nearby communities Arlington, Belmont, Boston, Brookline, Somerville and Watertown.
“Today’s announcement is a compelling indicator that the threat of mosquito-borne illness is widespread, and people should continue taking simple, common-sense steps to protect themselves and their families against mosquito bites,” Department of Public Health Commissioner John Auerbach said.
He advised people to use insect repellant, cover their skin and avoid outdoor activities at dusk and after nightfall, when mosquitoes are most active. Health officials also recommend draining standing water from buckets, kiddie pools and other places where mosquitoes breed.
The Centers for Disease Control and Prevention says only about one in five infected people get sick. One in 150 infected people will develop severe symptoms including neck stiffness, disorientation, coma and paralysis. Most infections are usually reported in August and September.
The West Nile virus has been found in 67 Massachusetts communities in nine counties this year. There were six cases in humans and one in a horse last year.
The virus was first reported in the U.S. in 1999 in New York and gradually spread across the country over the years. It peaked in 2002 and 2003, when severe illnesses reached nearly 3,000 and deaths surpassed 260. Last year was mild, with fewer than 700 cases.
On Thursday, state health officials also announced that another mosquito-borne illness, Eastern equine encephalitis, has been confirmed in a horse in Georgetown and in an alpaca in Halifax.
As a result, the EEE threat level has been raised to critical, the highest of five levels, in Georgetown, and to high in nearby Boxford, Groveland, Newbury, Rowley and West Newbury, health officials said. The EEE threat level has been raised to critical in Halifax and to high in neighboring East Bridgewater, Hanson, Pembroke and Plympton.
The threat levels run from remote (human cases highly unlikely at this time) to low, moderate, high and critical (multiple cases extremely likely).
Health officials said they “strongly” recommend that evening outdoor events be curtailed in all the high- or critical-risk communities for the rest of the mosquito season.
There has been only one confirmed human case of EEE in Massachusetts this year: a Metrowest resident who may have contracted it out of state.