The Eradication of Smallpox

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On May 8, 1980, officials from the World Health Organization announced that smallpox, the disease which had ravaged humanity across the world for millennia, had been eradicated. 

Over the last century before the eradication of smallpox, it is estimated to have killed half a billion people. 

Learn more about humanity’s deadliest disease and how it was eradicated on this episode of Everything Everywhere Daily.

Smallpox, also known as the variola virus, is the deadliest disease in human history. 

Full stop. 

More deadly than all the wars ever fought. More deadly than bubonic plague, cholera, influenza, or as far as we know, anything. 

If you contracted smallpox, your odds of dying were about 30%. Less lethal than Ebola, but far more virulent. It inhabited the deadly sweet spot of lethality and virulentness.

We aren’t sure when smallpox first reared its head and infected humans. It was probably around 10,000 to 12,000 years ago when humans first domesticated animals. Our best guess is that it first appeared in northeastern Africa where it mutated from an African rodent poxvirus which is its closest related virus in nature. 

The first evidence we have of the disease comes from ancient Egypt. Some mummies from around 1500 BC have been found with smallpox skin lesions. There was evidence on the corpse of Pharaoh Ramses V of smallpox scarring. 

From there the disease probably spread via traders to India, and from there to the rest of Asia. There are reports of smallpox in Ancient Chinese text as well as in ancient Sanskrit writings. 

The disease spread slowly as humans traveled slowly. As trade between countries grew, the disease spread. 

The disease tended to spread in large outbreaks. 

Many of the early plagues in antiquity, prior to the plague of Justinian, of which I did a previous episode, were probably smallpox. 

The plague of Athens in 430 BC was probably smallpox. It was said to have come from Egypt or Ethiopia. 

The Antonine Plague which hit the Roman Empire from 165 to 180 CE might have been smallpox as well. 

In 735 CE smallpox reached Japan and it is estimated to have killed ? of the population. 

These epidemics kept springing up all over Europe, Africa, and Asia. 

Being wealthy didn’t protect you. Kings and Queens could fall victim just as easily as the poor. Habsburg Emperor Joseph I, Queen Mary II of England, Czar Peter II of Russia,  King Louis XV of France, as well as an Ethiopian king, a Chinese emperor, and two Japanese emperors all died from smallpox.

However, it was nothing compared to what happened in the New World. 

Smallpox was unknown in the Americas. No one in North or South America had any resistance to the disease. 

The size of the population in the Americas at the time is unknown, but estimates range as high as 100 million. 

While smallpox wasn’t the only disease brought from the old world to the new, it was certainly the worst. Estimates that in the first century after European contact as many as 90% of the people in the Americas might have died. Most of this was unrecorded and was before the vast majority of the people ever laid eyes on a European. 

The disease spread before Europeans showed up in most places and they found a vastly depopulated land. One of the reasons why such vast herds of buffalo were found on the great plains may have been due to this massive depopulation of native people from disease. 

Even if you didn’t die from smallpox, the effects could last a lifetime. Smallpox scarring was often severe. If you’ve ever seen an image of Queen Elizabeth I with thick white makeup all over her face, that was there to hide the scarring from smallpox. 

The earliest records indicate that the fight against smallpox began China around the tenth century. 

There are two strains of the smallpox virus. Variola major and variola minor. There is evidence that the Chinese used exposure to the variola minor virus to provide lifelong resistance to both strains. This technique became known as inoculation, or more specifically to smallpox, variolation.

The Chinese would take scabs from recent smallpox victims, dry them, and then blow the power into someone’s nose. 

The process of variolation wasn’t foolproof. Fatality rates could range from 0.5 to 2 percent, but it was much better than the 30% from getting a full-blown case of the disease. 

By the 17th century, variolation was very common in China and Africa, but it was still shunned in Europe. It was considered folklore and not something which serious medicine would consider. They were more worried about applying leeches to remove evil humors at the time. 

One of the first Europeans to adopt the practice was Lady Mary Wortley Montagu who first observed the practice when she visited the Ottoman Empire. 

It was also adopted in the 18th century United States when the practice was used by African slaves who brought the technique with them. It was adopted by Cotton Mather, who is perhaps better known for such scientific endeavors as the Salem Witch Trials. 

The next big advance came in the late 18th century from English physician Edward Jenner. It had been observed that people who contracted a similar, but much less deadly disease called cowpox, would develop an immunity to smallpox. This was especially obvious in milkmaids, young women hired to milk cows and do dairy work, seemed to be immune to smallpox.

In 1796, he famously took the pus from a cowpox sore from a milkmaid by the name of Sarah Nelmes and inoculated 8-year-old James Phipps, the son of his gardener. The cow she got the infection from was called Blossom, and its hide now hangs in the St. George Medical School Library in England.

The boy developed a fever, but then nothing more. Subsequent exposure to smallpox showed he developed an immunity.  He tested it on 23 other patients, including his 11-month-old son.

He called this technique, vaccination. 

His technique quickly spread around the world. Napoleon had all his troops vaccinated. He gave Jenner a medal, even though he was fighting the English at the time. Bavaria and Denmark made vaccination mandatory in 1810.

In an earlier episode, I mentioned that agronomist Norman Borlaug had saved more people than anyone else in history. Edward Jenner might very well be in competition for that title. 

Through the 19th and 20th centuries, our knowledge of diseases and viruses improved, and vaccines got much better. Smallpox still killed millions around the world, but the disease was finally getting under control. We began to create smallpox vaccines in the laboratory and didn’t require another person to vaccinate someone. 

Unlike other diseases like the bubonic plague which is spread by rats, smallpox was only spread by humans to other humans. That meant that it was possible to actually eradicate smallpox. 

By 1949, the United States had its last case of smallpox. In 1950, the Pan American Health Organization set about an eradication program for all of the western hemisphere. 

In 1963, Europe saw its next to last case in Stockholm, which came from a sailor who brought it with him from Asia.

In 1958, the World Health Organization announced the goal of the complete global eradication of smallpox. This had mostly been achieved in developed countries, but there were still millions of cases per year in Africa and Asia. In 1967, they announced the final phase to completely eradicate the disease.

They set up a mass vaccination program for developing countries as well as a quick response program for reported cases. They even offered bounties to people who were able to report smallpox cases.

Within 10 years, the number of global cases went from millions to zero. 

The last naturally occurring case of the variola major virus occurred in Bangladesh in 1975. The last case of variola minor was in Somalia in 1977. 

The last case of smallpox in the world, and the last person to die from the disease, was not a natural case. In 1978, Janet Parker, a photographer at the Birmingham University Medical School in England contracted smallpox after working on the floor above the lab where research on the virus was being done. 

In 1980, after two years without a single case, the WHO announced to the world that smallpox, the most lethal disease in the history of humanity, had been eradicated. 

Since the announcement of the eradication of smallpox, the issue hasn’t quite gone out of the news. After the eradication, all known stockpiles of the virus were destroyed, with two exceptions.

There are still frozen samples of the smallpox virus kept at research facilities in the United States’ Centers for Disease Control and Prevention in Atlanta and Russia’s State Research Center of Virology and Biotechnology in Moscow. 

These two remaining samples have caused considerable debate over the last 40 years. On one hand, having frozen samples of the virus allows us to create vaccines in the unlikely event that smallpox should rear its head again in the future. Concerns are that it might come from terrorists who dig up corpses of smallpox victims or from some hidden corner of the world where it has lain dormant.

On the other than, the stockpiles themselves might be the greatest threat of the virus spreading again. If the virus were to get loose, the impact could be devastating. 

Today, most of the world has no immunity to smallpox. No one under the age of 40 has received a smallpox vaccine because they stopped issuing them once the disease was declared eradicated. 

If smallpox were to rear its head again, it could be a replay of what happened when it was brought to the new world, except this time globally.