Yellow fever (YF) is a viral disease, endemic to tropical regions of Africa and 
the Americas, which principally affects humans and nonhuman primates and is 
transmitted via the bite of infected mosquitoes. Yellow fever virus (YFV) can 
cause devastating epidemics of potentially fatal, hemorrhagic disease. Despite 
mass vaccination campaigns to prevent and control these outbreaks, the risk of 
major YF epidemics, especially in densely populated, poor urban settings, both 
in Africa and South America, has greatly increased. Consequently, YF is 
considered an emerging, or reemerging disease of considerable importance. This 
article comprehensively reviews the history, microbiology, epidemiology, 
clinical presentation, diagnosis, and treatment of YFV, as well as the vaccines 
produced to combat YF.