E-Mail IMAGE: Monkey being examined in Manaus area. Scientists will monitor areas in which these diseases are endemic to investigate the factors that trigger outbreaks view more Credit: CREATE-NEO By Maria Fernanda Ziegler | Agência FAPESP – Yellow fever was the first human disease to have a licensed vaccine and has long been considered important to an understanding of how epidemics happen and should be combated. It was introduced to the Americas in the seventeenth century, and high death rates have resulted from successive outbreaks since then. Epidemics of yellow fever were associated with the slave trade, the US gold rush and settlement of the Old West, the Haitian Revolution, and construction of the Panama Canal, to cite only a few examples.