Smallpox

• 1. Freedom From Smallpox

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  On the 26th of October 1977, a hospital cook named Ali Maow Maalin fell ill in Merca, Somalia. His was the last naturally occurring case of indigenous smallpox in the world. Two years later, on the 9th of December 1979, a commission of scientists certified that the disease was gone. The World Health Assembly endorsed that finding on the 8th of May 1980. Smallpox became the only human disease ever to be eradicated. For most of recorded history this would have seemed impossible. The disease killed about 30 percent of those it infected. It left survivors scarred for life, and it left some of them blind. In the last 100 years of its existence, it is thought to have killed at least 500 million people. By comparison, all the wars on the planet during that same span killed an estimated 150 million. How does a disease that old, that lethal, and that widespread simply stop existing? Who decided to chase it to extinction, and how did they corner it in the Horn of Africa? What did it actually do to a human body, and why did royalty fear it as much as the poor? And in an age when its genome sits in two freezers, can a disease ever truly be said to be gone?

• 2. What The Pox Did

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  By days 12 to 15 of infection, small reddish spots called enanthem appeared on the mouth, tongue, palate, and throat. These lesions ruptured and flooded the saliva with virus, which is how the disease passed to the next person. A rash then spread across the skin within 24 to 48 hours, beginning on the forehead and racing across the face before reaching the limbs and trunk. Variola virus attacked skin cells directly, producing the pimples, or macules, that gave the disease its character. The ordinary type accounted for at least 90 percent of cases among the unvaccinated, and its progression was almost a calendar. By the second day of the rash the macules became raised papules. By the third or fourth day they filled with an opalescent fluid, becoming vesicles, which turned turbid into pustules within 24 to 48 hours. By the sixth or seventh day every lesion was a pustule. These were sharply raised, round, tense, and deeply embedded in the dermis, giving them the feel of a small bead under the skin. Doctors could once diagnose smallpox by touch alone because the pustules were so distinctively hard. The rash was densest on the face and on the far ends of the limbs, and it almost always involved the palms and the soles. By days 16 to 20 scabs covered every lesion and began to flake off, leaving depigmented scars. Between 65 and 80 percent of survivors carried deep pitted pockmarks, most prominent on the face.

• 3. The Worst Forms

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  In one case series, the confluent type of ordinary smallpox killed 62 percent of patients. In that form the blisters merged into sheets that detached the outer layers of skin from the flesh beneath, and patients often stayed ill even after every lesion had scabbed over. Far rarer and far deadlier were the malignant and hemorrhagic forms. Malignant smallpox, also called flat smallpox, kept its lesions almost flush with the skin where raised vesicles should have formed. It accounted for 5 to 10 percent of cases, and most of its victims, 72 percent, were children. The vesicles held little fluid and felt soft and velvety, and death usually came between the eighth and twelfth day of illness. A day or two before the end, the lesions often turned ashen gray. Hemorrhagic smallpox brought extensive bleeding into the skin, mucous membranes, and internal organs. Bleeding under the skin made it look charred and black, which earned the name variola nigra, or black pox. The early or fulminant form, called purpura variolosa, killed suddenly between the fifth and seventh days, often when only a few skin lesions had appeared. Its case fatality rate approached 100 percent. Pregnant women were strikingly more vulnerable, making up roughly 16 percent of early hemorrhagic cases among unvaccinated women, against about 1 percent in nonpregnant women and adult men. Vaccination offered no apparent immunity to either hemorrhagic form, and some cases struck people revaccinated only shortly before.

• 4. A Disease Of Kings

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  Louis XV of France, Queen Mary II of England, Emperor Joseph I of Austria, King Louis I of Spain, Tsar Peter II of Russia, and Queen Ulrika Eleonora of Sweden all died of smallpox. The disease did not respect rank. Its earliest evidence dates to around 1500 BCE in Egyptian mummies, and the mummy of Ramses V, who died in 1145 BCE, carries a smallpox-like disease. From ancient India, where it may have stayed endemic for at least 2000 years, the disease spread east. It probably reached China in the 1st century CE and was carried from China to Japan in the 6th century. In Japan, the epidemic of 735 to 737 is believed to have killed as much as a third of the population. At least seven religious deities were dedicated to smallpox, among them the god Sopona in the Yoruba religion of West Africa and the Hindu goddess Shitala, worshipped in temples across India. The disease reshaped the Americas after Europeans arrived. Smallpox reached Hispaniola in 1507 and the mainland in 1520, carried by Spanish settlers into Mexico. Native populations had no acquired immunity, and case fatality rates in some outbreaks ran as high as 90 percent. These losses helped the Spanish conquer the Aztecs and the Incas. In 18th-century Europe the disease killed an estimated 400,000 people every year, and caused one-third of all cases of blindness. As recently as 1967-15 million cases occurred annually.

• 5. From Scabs To Vaccine

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  In China, powdered smallpox scabs were blown up the noses of healthy people, who would then develop a mild case and gain lifelong immunity. The Chinese author Wan Quan, who lived from 1499 to 1582, made the first clear reference to this inoculation in a work published in 1549, though hints of the practice reach back to the 10th century. The technique carried a 0.5 to 2 percent risk of death, far below the 20 to 30 percent of the disease itself. Two reports on the Chinese practice reached the Royal Society in London in 1700. Lady Mary Wortley Montagu observed inoculation in the Ottoman Empire and promoted it in England after returning in 1718. In 1721, Cotton Mather and colleagues stirred controversy in Boston by inoculating hundreds. Dr Thomas Dimsdale was invited to Russia and successfully variolated Empress Catherine the Great and her son Grand Duke Paul in 1768. Then in 1796, Edward Jenner, a doctor in Berkeley, Gloucestershire, found that material from a cowpox lesion could produce immunity to smallpox. He named the material vaccine, from vacca, the Latin word for cow. The procedure was far safer than variolation and carried no risk of spreading smallpox. Studies of European cases in the 1950s and 1960s showed the power of that protection. The fatality rate was 1.3 percent among people vaccinated less than 10 years before exposure, rising to 11 percent for those vaccinated 20 or more years earlier. Among the unvaccinated, 52 percent died.

• 6. Target Zero

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  In 1958, Professor Viktor Zhdanov, Deputy Minister of Health for the USSR, called on the World Health Assembly to launch a global campaign against smallpox. It was the Soviet Union's first appearance at the Assembly after a nine-year absence from the United Nations, and the proposal was accepted in 1959. For years the effort starved on roughly 100,000 dollars annually, even as 2 million people died of smallpox each year. In 1966 an international team, the Smallpox Eradication Unit, formed under the American physician Donald Henderson. When the formal effort began in 1967, the World Health Assembly set a ten-year goal called Target Zero, and the WHO raised its annual contribution to 2.4 million dollars. The strategy did not rely on vaccinating everyone. Instead, each outbreak was stopped by isolating cases and vaccinating everyone nearby, a method known as ring vaccination. It worked because humans were the only reservoir for the virus and no carrier state existed. By the end of 1975 smallpox survived only in the Horn of Africa, where civil war, famine, and refugees made the final push brutally hard. The last case of the deadlier variola major was a three-year-old Bangladeshi girl, Rahima Banu, detected in October 1975. The Australian microbiologist Frank Fenner directed the final surveillance and verification. The ten-year goal was missed by only nine months. The United States, the largest contributor to the roughly 300 million dollar effort, has reportedly recouped that investment every 26 days since.

• 7. Two Freezers Of Death

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  Two live samples of variola major virus remain, one at the CDC in Atlanta and one at the Vector Institute in Koltsovo, Russia. Every research proposal involving them must be approved by the WHO and the World Health Assembly. The WHO first recommended destruction of the virus in 1986 and set a date of the 30th of December 1993, then postponed it to the 30th of June 1999. Resistance from the United States and Russia kept the stocks alive, and in 2002 the World Health Assembly agreed to permit their temporary retention for specific research. A 2010 review by public health experts appointed by the WHO concluded that no essential public health purpose was served by retaining the virus. The danger is no longer only the freezers. The complete coding sequence of variola major is publicly available online, which has raised the fear of illicit synthesis. In 2002, NIH scientists artificially synthesized vaccinia, a cousin of variola. In 2016, another group synthesized horsepox from public sequence data, and in 2017 scientists at the University of Alberta recreated an extinct horse pox virus for about 100,000 dollars, without specialist knowledge. The WHO bans any single laboratory from synthesizing more than 20 percent of the genome at a time, but a group acting in bad faith could assemble fragments from multiple sources. Smallpox also has a documented history as a weapon. During Pontiac's War in 1763, at British-held Fort Pitt, commanders gave a Delaware delegation blankets taken from the smallpox hospital. Sir Jeffrey Amherst had written, "Could it not be contrived to send the small pox among the disaffected tribes of Indians?" The effectiveness of that effort is unknown.