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Kids with yellow fever in Mississippi about 1870. See how all the people are white? The hospital wasn't letting black kids in, or hiring black women as nurses.

Kids with yellow fever in Mississippi about 1870. See how all the people are white? The hospital wasn’t letting black kids in, or hiring black women as nurses.

Where did yellow fever get started?

The virus that causes yellow fever probably evolved from an earlier virus that didn’t make people sick. The first cases of yellow fever may have been in East or Central Africa. But people in West Africa were catching yellow fever by 1600 AD. Like most sicknesses, yellow fever slowly became a disease most people caught as children. If you got it when you were a child, it didn’t make you very sick, and then you couldn’t catch it again.

What is a virus?
Medieval West Africa
All our Africa articles

How did yellow fever spread to the Americas?

When slave traders forced people from West Africa to travel to North and South America in the 1600s to work as slaves, apparently some of them had yellow fever. So the virus came to the Americas with them. But in the Americas, people hadn’t had yellow fever when they were children. They caught it as adults, and it made them very sick.

African-American slavery
Ghana and colonization

How did you catch yellow fever?

You caught yellow fever when a mosquito bit an infected person and then bit you. If you caught yellow fever, you got a sudden fever and headache. Most people slowly got better, but about a third of the people who caught yellow fever got bad cases.

More about mosquitoes
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What happens when you get yellow fever?

If you got a bad case of yellow fever, you became extremely tired and began bleeding into the skin. You got a slow heartbeat, back pains, and vomiting. Then your liver stopped working, and your skin turned yellow with poisons that your liver couldn’t filter out (That’s why it’s called yellow fever). About half the people who got bad cases, or one out of every seven people who caught yellow fever, died.

Yellow fever epidemics in the Americas

Better safe than sorry! Get a mosquito net

Better safe than sorry! Get a mosquito net

When mosquitoes bit these African people, they spread yellow fever to other people. In 1648, yellow fever killed a lot of people in the Maya country. In 1685, it killed a lot of people in Brazil. And in 1793, an epidemic of yellow fever killed a lot of European colonists in Philadelphia. People in Philadelphia thought African-Americans couldn’t catch yellow fever, but really it was only people born in Africa, who had had it as children, who were immune. Black Americans, born in the Americas, did catch yellow fever just like white people, and many died of it.

By 1822, after a serious epidemic in New York City, northern port cities began to quarantine ships as they came into port to stop yellow fever, and there were no more epidemics in the north.

But many people continued to die of yellow fever in the American South and in the Caribbean islands and Brazil, where there were a lot of mosquitoes to spread the disease.

A vaccination against yellow fever

In 1881, Carlos Finlay, a Cuban doctor, suggested that mosquitoes might be spreading yellow fever, and when Walter Reed’s experiments showed he was right, people began to work hard to get rid of the mosquitoes. This effort stopped most of the yellow fever epidemics.

What is vaccination?

In 1937, Max Theiler, who was originally from South Africa but was working in New York, invented a vaccination against yellow fever. Because of the vaccination, and programs to control mosquitoes, not very many people catch yellow fever anymore, though there’s still no cure for yellow fever if you do get it.

Learn by doing: get appropriate vaccinations for where you live!
Read about malaria

Bibliography and further reading about yellow fever:

Dengue Fever
Bubonic plague (with pictures)
History of Medicine home