A British tourist went into a comma after bitten by a mosquito while vacationing in the US. The mosquito bite carry the virus, known as Eastern Equine Encephalitis or Triple E, the most the most serious mosquito-borne diseases on the North American continent.
http://news.bbc.co.uk/2/hi/uk_news/scotland/edinburgh_and_east/7033203.stmI think that Deet is the only protection against mosquitos. There is no vaccine for this disease.