Clinical Features Yellow fever is an acute viral disease of short duration with a wide variation in intensity. The classic triad of jaundice, haemorrhage and severe albuminuria is present only in a small number of severe cases. In mild cases, the only symptoms may be headache and fever or a 'dengue-like' illness with fever, chills and myalgia.
Malignant cases have three characteristic stages of infection, remission and intoxication.
On the third day, the fever falls by crisis and patient enters remission. Public Health Significance and Occurrence Yellow fever is confined by the ecosystem and suitable vectors. It is endemic in Central America and Central Africa, but outbreaks may occur in unaffected areas if mosquitoes are infected by migrating humans or monkeys. The case fatality is 5 per cent in indigenous populations in endemic areas. In non-indigenous individuals or during epidemics it may be 50 per cent.