British man in coma after being bitten by mosquito in the U.S.

Oct 8 2007

A man in Britain is in a coma after being bitten by a mosquito carrying a rare and potentially fatal virus.

Michael Nicholson, 35, from Livingston in west Lothian, remains in a critical condition in the neurological unit of Western General hospital in Edinburgh after contracting the eastern equine encephalitis virus, also known as Triple E; he had been holidaying on the east coast of the U.S.

According to his family, the painter and decorator who is the first European to contract Triple E, was infected when bitten while fishing in New Hampshire on the east coast of the U.S. in August.

Mr Nicholson spent six weeks in Rhode Island and New Hampshire and stayed in a log cabin on the Saco River in northern New Hampshire.

He became ill on August 31, a day after flying home and within two days he had lost consciousness and the family say doctors diagnosed Triple E on September 13th.

Triple E is one of the most deadly mosquito-borne diseases.

Although transmission to humans is rare and only five people on average are infected in the U.S. each year; there is no effective treatment and of those who survive approximately half will have mild to severe permanent neurologic damage.

Doctors have warned the family that if he survives Mr Nicholson will almost certainly be severely disabled for the rest of his life because of brain damage.

Triple E is found in North America, central and south America, and the Caribbean.

Most cases in the U.S. have been from the eastern seaboard states and the Gulf coast and health records show that there were 220 confirmed cases of Triple E between 1964 and 2004, an average of five per year.

According to reports there has been one death this year in the U.S., that of a six-year-old boy in Alabama.

Triple E was first recorded in Massachusetts in 1831 when 75 horses died of encephalitic illness and the first human cases appeared in 1938 when 30 children died in the northeastern states.

The virus operates through a bird-mosquito cycle that intensifies through the summer, as more birds and mosquitoes become infected.

Many persons infected with Triple E have no apparent illness, but in those who do develop illness, symptoms range from mild flu-like illness to inflammation of the brain, coma and death.

Triple E transmission is most common in and around freshwater hardwood swamps in the Atlantic and Gulf Coast states and the Great Lakes region and residents and visitors to endemic areas are most at risk.

People over age 50 and younger than age 15 seem to be more susceptible to developing Triple E when infected with the virus.

Transmission to humans is however rare and it usually takes from three to ten days to develop symptoms.

Many infected people have no apparent illness but for those who do become ill there is no specific treatment and up to 35 per cent of victims die.

While a vaccine is available to protect horses there is nothing for humans; the CDC recommends people use repellents to avoid mosquito bites.