The virus has an incubation period of 3-6 days. The mosquito is the yellow fever virus, so transmission occurs via mosquito bites. The virus is also preserved in mosquito eggs through their incubation period, thus ensuring existence of the virus each year.
Yellow fever is located only in Africa and South America.
An indication of yellow fever infection is that the high fever is associated with a relatively slow pulse. Half of these patients in the toxic phase die within 10-14 days. A yellow fever vaccine is available and should be taken by travelers to endemic areas. It is a safe, effective live virus vaccine that has been used for several decades and confers immunity for 10 years or more. Side effects occur in very few vaccinees.