Close-up of yellow fever mosquito.

In 1793, Philadelphia, Pennsylvania, then the nation’s capital, experienced the first major outbreak of yellow fever in the United States. Around 17,000 of the city’s 45,000 population left for the countryside, while an estimated 5,000 died as a result of the virus, which peaked in early October.

Fever Origins

At the time, people believed that yellow fever originated in rotting vegetables and other organic matter. Philadelphia physician Benjamin Rush was convinced that the 1793 outbreak was due to a large amount of coffee beans that had been left to rot at the city’s docks. Today scientists know that yellow fever is spread by mosquitoes. The virus was well-known in the Caribbean region and may have been brought to Philadelphia by refugees fleeing a revolution on the island of Saint Domingue, known today as Haiti.

Treating Symptoms

Infected people could be identified by their physical symptoms. A high fever was accompanied by color changes: Eyes and skin turned yellow, giving the virus its name, while other areas of skin became purple as the patient suffered internal bleeding. Victims bled from the nose and ears, while their stools and vomit turned black, known as “coffee grounds.” Eventually they fell into comas as their internal organs failed. Physician Rush pursued a very aggressive treatment regimen for the patients under his care, involving heavy bleeding and the administration of calomel, a compound of mercury.


Philadelphia’s free African-American community stood around 2,000 strong before the outbreak, and played an important role in reacting to it. Their contribution in caring for the ill and dealing with the bodies of those who died is “widely regarded as a formative event in the history of black Philadelphia,” says Simon Finger, Ph.D., of Princeton University. Black volunteers Absolom Jones and Richard Allen published their account of events the following year to publicize the humanitarian work done by free blacks in response to the epidemic.

Fever Aftermath

Yellow fever returned to Philadelphia seven times in the 12 years after 1793, each time stopped only by the winter frosts that killed the mosquitoes. The outbreaks were one factor behind Philadelphia’s declining importance as a seaport in the 1800s, as other northern ports like New York overtook it. However, the 1793 epidemic led directly to improvements in the city’s sanitation, while local authorities built hospitals and isolation facilities to help deal with any future outbreaks.