It can be recognized from historic texts stretching back 400 years.
Infection causes a wide spectrum of disease, from mild symptoms to severe illness and death.
Although a safe and effective vaccine has been available for 60 years, the number of people infected over the last two decades has increased and yellow fever is now a serious public health issue again. South America has two different types, but since 1974 only one has been identified as the cause of disease outbreaks. The virus remains silent in the body during an incubation period of three to six days. There are then two disease phases. Often, the high fever is paradoxically associated with a slow pulse.