A Briton has become the first European to contract a rare and potentially fatal mosquito-borne virus which attacks the central nervous system. Michael Nicholson, 35, was in a critical condition in a coma in the Western General hospital in Edinburgh last night after contracting the eastern equine encephalitis virus, also known as Triple E, while holidaying on the east coast of the US.

Mr Nicholson, a painter and decorator from Livingston in west Lothian, was infected when bitten while fishing in New Hampshire in August, according to his family. 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 US each year. There is no effective treatment.

Sharan McKenzie, Mr Nicholson's sister, said her brother was unresponsive and only occasionally opened his eyes. Doctors had warned the family that if he survived he would almost certainly be severely disabled because of brain damage.

Mrs McKenzie, 38, said: "You don't think there is going to be a risk if you get bitten by a mosquito in the US ... our family has been devastated by this."

Mr Nicholson spent six weeks in Rhode Island and New Hampshire this summer and fell ill on August 31, a day after flying back to Scotland. Within two days he had lost consciousness. Mrs McKenzie said doctors diagnosed him with Triple E on September 13, telling the family that his case was the first in Europe.

Triple E is found in North America, central and south America, and the Caribbean. In the US, most cases have been reported mostly from the eastern seaboard states and the Gulf coast.