The United States endured outbreaks of malaria and yellow fever throughout the 18th and 19th centuries. These diseases were previously foreign to the Americas (and to the original homelands of most of the colonists in Northern Europe). They arrived in the United States from their place of origin in Africa via the slave trade (either directly, or from Africa to S. America or the Caribbean and thence to the United States).

These diseases were also common (and feared) by European colonists in Africa.