Yellow fever epidemiology and demographics

Epidemiology
Yellow fever occurs only in Africa, South and Central America, and the Caribbean. Most outbreaks in South America are to people who work within the tropical rain forests and have direct contact with the organisms within the rainforest. The disease can remain locally unknown in humans for long periods of time and then suddenly break out in an epidemic fashion. In Central America and Trinidad, such epidemics have been due to a form of the disease (jungle yellow fever) that is kept alive in Red Howler monkey populations and transmitted by Haemagogus mosquito species which live only in the canopy of rain forests. The virus is passed to humans when the tall rainforest trees are cut down. Infected woodcutters can then pass on the disease to others via species of Aedes mosquitoes that typically live at low altitudes, thus triggering an epidemic.