How we conquered the deadly smallpox virus - Simona Zompi

8,826,071 views ・ 2013-10-28

TED-Ed


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10,000 years ago,
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a deadly virus arose in northeastern Africa.
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The virus spread through the air,
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attacking the skin cells,
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bone marrow,
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spleen,
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and lymph nodes of its victims.
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The unlucky infected developed fevers,
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vomiting,
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and rashes.
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30% of infected people died
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during the second week of infection.
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Survivors bore scars and scabs
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for the rest of their lives.
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Smallpox had arrived.
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In 1350 B.C., the first smallpox epidemics
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hit during the Egypt-Hittite war.
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Egyptian prisoners spread smallpox
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to the Hittites,
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which killed their king
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and devastated his civilization.
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Insidiously, smallpox made its way around the world
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via Egyptian merchants,
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then through the Arab world with the Crusades,
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and all the way to the Americas
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with the Spanish and Portuguese conquests.
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Since then, it has killed billions of people
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with an estimated 300 to 500 million people
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killed in the 20th century alone.
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But smallpox is not unbeatable.
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In fact, the fall of smallpox started
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long before modern medicine.
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It began all the way back in 1022 A.D.
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According to a small book, called
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"The Correct Treatment of Small Pox,"
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a Buddhist nun living in a famous mountain
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named O Mei Shan
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in the southern providence of Sichuan
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would grind up smallpox scabs
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and blow the powder into nostrils of healthy people.
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She did this after noticing
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that those who managed to survive smallpox
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never got it again,
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and her odd treatment worked.
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The procedure, called variolation,
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slowly evolved
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and by the 1700's,
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doctors were taking material from sores
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and putting them into healthy people
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through four or five scratches on the arm.
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This worked pretty well
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as inoculated people would not get reinfected,
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but it wasn't foolproof.
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Up to three percent of people
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would still die after being exposed to the puss.
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It wasn't until English physician Edward Jenner
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noticed something interesting about dairy maids
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that we got our modern solution.
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At age 13, while Jenner was apprentice
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to a country surgeon and apothecary
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in Sodbury, near Bristol,
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he heard a dairy maid say,
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"I shall never have smallpox, for I have had cowpox.
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I shall never have an ugly, pockmarked face."
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Cowpox is a skin disease
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that resembles smallpox and infects cows.
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Later on, as a physician,
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he realized that she was right,
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women who got cowpox didn't develop
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the deadly smallpox.
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Smallpox and cowpox viruses are from the same family.
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But when a virus infects an unfamiliar host,
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in this case cowpox infecting a human,
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it is less virulent,
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so Jenner decided to test
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whether the cowpox virus could be used
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to protect against smallpox.
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In May 1796, Jenner found a young dairy maid,
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Sarah Nelmes,
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who had fresh cowpox lesions on her hand and arm
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caught from the utters of a cow named Blossom.
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Using matter from her pustules,
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he inoculated James Phipps,
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the eight-year-old son of his gardener.
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After a few days of fever and discomfort,
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the boy seemed to recover.
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Two months later, Jenner inoculated the boy again,
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this time with matter from a fresh smallpox lesion.
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No disease developed,
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and Jenner concluded that protection was complete.
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His plan had worked.
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Jenner later used the cowpox virus
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in several other people
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and challenged them repeatedly with smallpox,
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proving that they were immune to the disease.
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With this procedure,
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Jenner invented the smallpox vaccination.
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Unlike variolation, which used actual smallpox virus
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to try to protect people,
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vaccination used the far less dangerous cowpox virus.
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The medical establishment,
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cautious then as now,
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deliberated at length over his findings
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before accepting them.
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But eventually vaccination was gradually accepted
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and variolation became prohibited in England in 1840.
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After large vaccination campaigns
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throughout the 19th and 20th centuries,
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the World Health Organization certified
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smallpox's eradication in 1979.
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Jenner is forever remembered
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as the father of immunology,
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but let's not forget the Buddhist nun,
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dairy maid Sarah Nelmes, and James Phipps,
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all heroes in this great adventure of vaccination
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who helped eradicate smallpox.
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