about 2 days to 2 weeks after the bite of an infected mosquito, disease symptoms of a nonspecific summertime illness with sore throat, runny nose and cough, followed by fever, headache, nausea and vomiting can develop. neuroinvasive disease occurs in two thirds of reported cases and is characterized by severe headache and neck stiffness as in meningitis or increasing lethargy and altered mental status up to coma as in meningoencephalitis. no acute flaccid paralysis, no death and no acquisition from a blood transfusion has ever been reported.