"A Cow Head Will Not Erupt From Your Body If You Get A Smallpox Vaccine"

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Smallpox is one of the deadliest diseases known to humans - or was one of the deadliest diseases. It's eradication is among the greatest achievements of modern medicine. That story is told in a new exhibit at Johns Hopkins University in Baltimore. It starts with English milkmaids and the Eureka moment which led to the first vaccine. NPR Global Health correspondent Jason Beaubien reports.

JASON BEAUBIEN, BYLINE: It's important to remember that smallpox used to be terrifying. As late as the 1960s, it killed millions of people each year. There was no cure. It came with a rash of oozing blisters that scarred many of its victims for life. But when an English country doctor named Edward Jenner found a way to prevent it, he wasn't universally celebrated. A cartoon from 1802 on display at this exhibit lampoons Jenner, suggesting his vaccine will make cows' heads erupt from people's bodies.

Christine Ruggere, the curator of the historical collection at the Johns Hopkins School of Medicine, says at the turn of the 19th century, diseases were still mysterious. It wasn't clear how they spread. But Dr. Jenner noticed something about smallpox - milkmaids seemed to be immune.

CHRISTINE RUGGERE: In English literature and poetry, very often milkmaids are referred to for their creamy complexion - as pretty as a milkmaid. One of the reasons why they had such nice complexion was they didn't get smallpox.

BEAUBIEN: Jenner guessed that by being exposed to a bovine form of the disease - cowpox - milkmaids were protected from the much more lethal smallpox. So he set out to test his theory.

RUGGERE: Now, his experiments are not ones we do today. He took cowpox, gave it to a small boy. The boy got a good case of cowpox, was healed, then he took smallpox and injected it into the same child.

BEAUBIEN: The 8-year-old never developed smallpox. Jenner had just come up with the world's first vaccine. Still, religious leaders blasted it, saying it violates God's will. In 1966, Dr. D.A. Henderson went to Geneva to head up a campaign by the World Health Organization to eradicate smallpox entirely.

DR. D.A. HENDERSON: At the beginning of the program there were an estimated 10 million cases and two million deaths. The disease was present in some 31 countries at that time.

BEAUBIEN: Smallpox only travels from person to person, so the goal of the eradication campaign was to find cases and then vaccinate in circles around them.

HENDERSON: If you snipped the chain, you stopped the spread.

BEAUBIEN: By the mid-1970s, Ethiopia was one of the last smallpox holdouts. It was also in the midst of a bloody Marxist revolution. Getting around was so difficult that the vaccinators had to use helicopters.

HENDERSON: One was blown up with a hand grenade because the people thought it was the Italians coming back to occupy Ethiopia. Another time, they captured a helicopter and asked for ransom.

BEAUBIEN: Eventually they got their helicopter back, and the last case of smallpox ever recorded was on October 26 of 1977, in neighboring Somalia.

HENDERSON: It's the only disease of man which we have succeeded in eradicating.

BEAUBIEN: Jason Beaubien, NPR News, Baltimore.

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