<P> Fatality may occur when cytokine storm, shock, and multiple organ failure follow . </P> <P> Yellow fever is most frequently a clinical diagnosis, made on the basis of symptoms and the diseased person's whereabouts prior to becoming ill . Mild courses of the disease can only be confirmed virologically . Since mild courses of yellow fever can also contribute significantly to regional outbreaks, every suspected case of yellow fever (involving symptoms of fever, pain, nausea and vomiting six to 10 days after leaving the affected area) is treated seriously . </P> <P> If yellow fever is suspected, the virus cannot be confirmed until six to 10 days after the illness . A direct confirmation can be obtained by reverse transcription polymerase chain reaction where the genome of the virus is amplified . Another direct approach is the isolation of the virus and its growth in cell culture using blood plasma; this can take one to four weeks . </P> <P> Serologically, an enzyme linked immunosorbent assay during the acute phase of the disease using specific IgM against yellow fever or an increase in specific IgG - titer (compared to an earlier sample) can confirm yellow fever . Together with clinical symptoms, the detection of IgM or a fourfold increase in IgG - titer is considered sufficient indication for yellow fever . Since these tests can cross-react with other flaviviruses, like dengue virus, these indirect methods cannot conclusively prove yellow fever infection . </P>

Who led the battle against it and what were the symptoms