Yellow Fever is a viral infection that causes damage to the liver, kidney, heart and gastrointestinal tract. Major symptoms may include sudden onset of fever, yellowing of the skin (jaundice) and hemorrhage. It occurs predominately in South America, the Caribbean Islands and Africa. The disease is spread through bites of infected mosquitos. Incidence of the disease tends to increase in the summer as the mosquito population increases, and it occurs year round in tropical climates.
Yellow Fever has two cycles: the sylvan cycle in which mosquitos primarily spread the disease among forest-dwelling primates, and the urban cycle in which the infection is spread from human to human.