3.7 | Yellow Fever Outbreaks
Yellow fever is caused by a virus that originated in Africa. It is transmitted by the bite of an Aedes aegypti mosquito. Until the 19th century, it was not recognized that the disease spread through mosquitoes. Before that time, yellow fever was regarded as a dangerous infection . In the 19th century, yellow fever outbreaks were particularly common in the Americas, killing 100,000–150,000 individuals in the Southern United States.