Yellow Fever — An Epidemic That Changed America

1793

It was August 1793. Philadelphia was the country's largest city and the capital of the United States, home to some 50,000 people in tight houses near the river.

Refugees were arriving from Saint-Domingue (Haiti), fleeing revolution — French colonists with their slaves. The virus was transmitted by mosquitoes from one human to another, but at the time nobody suspected the mosquito. That connection would take nearly a century to establish.

Yellow fever — "the American plague," as it was known — is a viral disease that begins with fever and muscle pain. Victims often become jaundiced (hence "yellow"), as the liver and kidneys fail. Some suffered worse: the Puritan minister Cotton Mather, describing an earlier Boston outbreak, wrote of victims "turning yellow, then vomiting and bleeding every way." Internal bleeding in the digestive tract causes bloody vomit; many victims became delirious before dying.

The summer of 1793 was one of the hottest on record in Philadelphia, and humidity was unbearable. Streets emptied as people feared going out. Between August and October, nearly 5,000 people died and some 20,000 fled the capital. The rich — including George Washington and Thomas Jefferson — fled to the countryside; the poor stayed and fell sick. In a few months, about 10% of the population was wiped out. The epidemic peaked in October and then gradually subsided.

Nobody knew what was happening — one day a person was healthy, the next he was gone. People attributed the sickness to the only thing they could: the refugees. Since the onset had followed the arrival of the ships from Saint-Domingue, many were convinced the disease had come with them.

The refugees were ordered to quarantine for 21 days on their ships — which was difficult, and the sight of sick people aboard only cemented the belief.

Dr. Benjamin Rush, the physician who fought the epidemic, advised people to flee the city. But he blamed unsanitary conditions — open sewage, rotten vegetables, extreme heat — not the refugees. He led a cleanliness campaign through the city.

Rush also believed the city's free Black residents were immune to the disease, so he asked them to serve on the front lines nursing the sick. They were not immune — many, including organizers Absalom Jones and Richard Allen's volunteers, fell ill and died alongside the white victims.

Rush's treatments were even more dangerous than his theories. Reasoning that the blood of the sick had been infected, he practiced "bleeding and purging" — sometimes removing up to two-thirds of a patient's blood. His methods were unproven and often fatal. But his conviction gave a frightened population hope; those who opposed him called him a killer.

When winter set in, lakes froze, and the epidemic eased. The first frost killed the mosquitoes — the actual carriers — though nobody realized it. One newspaper noted that cold weather seemed to reduce the disease.

It was 1881 when Cuban physician Carlos Finlay first proposed that mosquitoes spread yellow fever; the Reed Commission confirmed it in 1900–1901 — over a century after Philadelphia's ordeal.

As the National Library of Medicine's exhibition documents, the epidemic quickly became political. Treasury Secretary Alexander Hamilton and other Federalists blamed the French refugees and favored closing ports and restricting immigration — turning a medical question into a political dispute.

Yellow fever changed Philadelphia forever: hospitals were built to care for the sick, open sewers were closed, and laws were passed requiring citizens to keep their dwellings clean. Despite his disastrous treatments, Rush also helped establish the first free dispensary in the United States.

During the American Plague, people were afraid of each other — afraid to meet friends, afraid to shake hands. Would COVID-19 leave us like this?

Sources: Wikipedia: 1793 Philadelphia yellow fever epidemic, NLM: The Politics of Yellow Fever, History.com. Originally published April 2020.