Last Natural Case of Smallpox Occurs Summary

  • Last updated on November 10, 2022

After decades of multinational effort, smallpox was officially eradicated when the last natural case occurred in Merca, Somalia, leaving scientists debating what to do with the remaining stocks of smallpox virus.

Summary of Event

On October 12, 1977, two smallpox patients from a nomadic encampment ninety kilometers outside the regional port of Merca, Somalia, were guided to the local smallpox office by a twenty-three-year-old cook named Ali Maow Maalin. Ten days later, Maalin fell ill, and on October 30, he was diagnosed with smallpox. Emergency medical teams were immediately established to vaccinate anyone who had been in contact with Maalin, all persons in the vicinity of his home in Merca, and all persons entering or leaving Merca. By November 14, more than fifty thousand people had been vaccinated to prevent a possible smallpox outbreak. Diseases;smallpox Smallpox [kw]Last Natural Case of Smallpox Occurs (Oct., 1977) [kw]Case of Smallpox Occurs, Last Natural (Oct., 1977) [kw]Smallpox Occurs, Last Natural Case of (Oct., 1977) Diseases;smallpox Smallpox [g]Africa;Oct., 1977: Last Natural Case of Smallpox Occurs[02980] [g]Somalia;Oct., 1977: Last Natural Case of Smallpox Occurs[02980] [c]Health and medicine;Oct., 1977: Last Natural Case of Smallpox Occurs[02980] Maalin, Ali Maow Jenner, Edward Zhdanov, Viktor M. Parker, Janet Bedson, Henry Samuel

On December 29, 1977, two months after Maalin’s smallpox was diagnosed and after a countrywide search revealed no further cases of smallpox, World Health Organization World Health Organization (WHO) officials determined that the potential for a smallpox outbreak—the last disease on WHO’s list of potential outbreaks—was over. A subsequent two-year surveillance period in the Horn of Africa, which contained the last endemic reservoirs of smallpox, revealed no further cases, and on December 9, 1979, the World Health Organization certified that smallpox had been eradicated. This event marked the end of a three-thousand-year association between humans and the smallpox virus. All that remained of smallpox were laboratory stocks of the virus maintained at the Centers for Disease Control (CDC) in Atlanta, Georgia, and the Research Institute of Viral Preparations in Moscow, Russia.

It is difficult to imagine the scourge smallpox once was as the collective memory of it recedes. Though not as deadly as some other infectious diseases, smallpox epidemics were so frequent and so widespread that some historians estimate that it killed more people throughout its reign than all other infectious diseases combined. Smallpox struck monarchs and paupers, the young and the old, Europeans, Asians, and Africans alike. Its route of transmission was unknown; its victims were horrible to look at. Their bodies became covered with raised pustules which, if the people survived, left their skin pock-marked. Frequently, however, the pustules ruptured, the skin sloughed away from the body, and the sick succumbed to a combination of tissue degeneration, blood poisoning, and secondary infections from ten to fifteen days after the pustules first appeared.

Smallpox was especially deadly when it appeared among groups who had not previously been exposed to it. When Spaniards first arrived in Mexico with Hernán Cortés in 1518, the native Aztec Empire was at the height of its power. Within two years, 3.5 million Aztecs had died of smallpox and within thirty years more than one-half of the native population had been killed by the disease.

Smallpox survivors were generally immune to further infection. This immunity caught the attention of medical practitioners, and as early as the tenth century c.e. the Chinese were using a practice called “variolation” to induce immunity to smallpox. Dried scabs from recovered smallpox victims were ground to a fine powder and blown into the nostrils of the person to be immunized; alternatively, some of the liquid from the pustules of a recovering smallpox victim were scratched into the arm of a recipient. The immunization caused a mild form of smallpox that the recipient usually survived. Variolation, however, could cause fatal cases of smallpox to develop in healthy individuals. In addition, since live smallpox virus was used, variolation, though it may have protected the individual, exposed the larger population to risk from transmission of the disease as long as the individual remained infectious.

There were three forms of smallpox: Variola major, true virulent smallpox, which usually caused death; Variola minor, a mild form of smallpox, which was not usually fatal; and Variola vaccinae, or cowpox, which was rarely fatal or disfiguring. Infection by one of these forms effectively prevented infection by the other two. This principle of immunity became the basis of vaccination, which was the process of inoculating persons with cowpox virus to immunize them against smallpox.

Vaccination was pioneered by Edward Jenner, a doctor practicing in Berkeley, England, in the late eighteenth century. There was some initial resistance to the idea of vaccination, but Jenner’s technique for immunizing against smallpox soon became widely adapted in the United States and continental Europe. As production of the smallpox vaccine increased, mass vaccination of individuals in industrialized nations became the norm, and the incidence of smallpox in these countries declined precipitously.

Travelers to developing nations were still routinely advised to receive vaccinations for smallpox, because it remained endemic in many parts of the world. In 1958, however, at a meeting of the World Health Assembly, Viktor M. Zhdanov, the deputy minister of health in the Soviet Union, proposed a radical multinational effort that called for complete global eradication of smallpox. Zhdanov’s success at eliminating smallpox in the Soviet Union had convinced him that smallpox was a likely candidate for control because of its identifiable symptoms, the limited period in which direct person-to-person transmission could occur, and the availability of vaccines.

By 1965, member countries of the World Health Organization were committed to a campaign of global smallpox eradication. Supplied with vaccine produced in the Soviet Union and the United States and armed with an effective device for administering vaccine, multinational teams spread around the globe to begin a program of mass immunization against smallpox. Vaccination of the entire world population soon proved infeasible, however, and a new strategy was developed that was based on a technique known as “expanding ring vaccination”: Only those who were at greatest risk of infection by smallpox were vaccinated. By using this strategy of selective vaccination in areas with known outbreaks of smallpox, containment of the source of smallpox transmission from person-to-person contact during the infectious period through quarantine, and remedial vaccination of all persons within the vicinity who might be exposed to smallpox, health officials believed that they could contain the spread of smallpox and then selectively eliminate it where it was known to occur.

This strategy of detection, containment, and surveillance was adopted in 1968 and, by 1977, culminated in the final outbreak of smallpox being detected and contained in Merca, Somalia. The final natural host of smallpox, Ali Maalin, was prevented from transmitting it. He recovered from the disease.


The World Health Organization published this poster after declaring smallpox eradicated on May 8, 1980.

(AP/Wide World Photos)

In 1978, a virulent strain of smallpox virus being studied in Henry Samuel Bedson’s virology laboratory in Birmingham, England, was accidentally released and found its way through a service duct to the office of a medical photographer named Janet Parker. She subsequently contracted smallpox even though she had been vaccinated. Bedson, who was distraught over his laboratory’s role in Parker’s infection, became critically ill after an apparent suicide attempt and died on September 7, 1978. Parker died on September 11. She is the last person known to have died of smallpox. Parker’s close contacts were revaccinated as a precautionary measure, but only her mother developed a clinically diagnosed case of smallpox; she recovered.

Tragedies such as this, and the fact that most countries had stopped routine vaccination for smallpox by 1985 (except for certain military personnel), leaving whole populations at risk for accidentally released smallpox, prompted world health officials to reevaluate the need to maintain widely dispersed stocks of smallpox virus. Eventually, the remaining live stocks of smallpox were consolidated in two locations, the Centers for Disease Control in Atlanta, Georgia, and the Research Institute of Viral Preparations in Moscow, Russia.

By the late 1980’s, technological advances in genetic engineering and deoxyribonucleic acid (DNA) sequencing made it possible to determine the entire genetic information of viruses such as smallpox. Consequently, in May, 1990, Louis Sullivan, the U.S. secretary of Health and Human Services, proposed to the World Health Assembly that the entire smallpox genome be sequenced and the remaining stocks of smallpox be destroyed. A World Health Organization committee, meeting that same year, set a December 31, 1993, deadline for destroying the last remaining stocks of smallpox virus as well as all other material that contained fragments of smallpox DNA.

Opposition and debate within the scientific and medical communities, however, prevented these final stocks from being destroyed as scheduled. Although the complete genetic information for the major types of smallpox virus had been virtually determined, questions arose as to the wisdom of destroying the original viral stocks regardless of their lethality.

Scientists who advocated the destruction of the smallpox stocks did so for two basic reasons. The most important reason was that millions of people were at risk from smallpox infection once vaccination programs ceased. Great fear was voiced that terrorists could obtain these stocks and use them to hold the world hostage; indeed, the September, 2001, deadly anthrax attacks in the United States raised concerns that smallpox could be used as a biological weapon. With the sequencing of the genetic information of smallpox, comparisons between smallpox, its proteins, and other known viruses could be done without using the intact smallpox virus. The advocates for smallpox destruction also reasoned that destruction of the last stocks would send a worldwide message that keeping clandestine stocks of smallpox and using them for biological warfare studies were clearly illegal acts. Eradication of smallpox, they argued, was not complete until these last stocks were destroyed.

The arguments against destroying the smallpox virus were numerous. It was claimed that the cost of guaranteeing the preservation and safety of the virus stocks was minimal compared with the insights that could be gained by further study of the smallpox virus. If the stocks were destroyed, there would no longer be an opportunity to study unique characteristics of the intact virus. Study of the intact smallpox virus was essential to an understanding of the relationship between its pathogenicity and other biological functions. Furthermore, it was believed that studying the pathogenicity of smallpox to human cells might reveal something about the pathogenicity of other viruses such as human immunodeficiency virus (HIV).

Scientists also argued that destroying the virus stocks in Atlanta and Moscow would be a largely a symbolic gesture because there was no assurance that clandestine stocks would not be maintained elsewhere. The possibility even existed that live virus was preserved in corpses buried in the Siberian permafrost. Scientists warned against complacency about infectious disease (there was a sudden resurgence of tuberculosis, for example, after years of decline) and against misguided attempts to reconstruct smallpox’s virulent elements. The live smallpox stocks were necessary so that smallpox did not simply become a textbook example of disease but one that demonstrated the need for eternal vigilance.

One argument against destroying all smallpox supplies was an ecological and ethical one. This argument pointed out that while the focus of many environmentalists was on preserving biological diversity, here was a case where scientists were deliberately trying to extinguish a virus. Once smallpox was gone, perhaps it could never be reconstructed; perhaps genetic sequences are not an adequate substitute for the real thing. Those who made this argument asked whether it is wise to reduce biodiversity, even if the organism in question is dangerous, when the future might reveal that it had some value after all. The question of the destruction of the smallpox virus stocks remained hotly debated and still unresolved in the early years of the twenty-first century. Diseases;smallpox Smallpox

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">Baxby, Derrick. Jenner’s Smallpox Vaccine: The Riddle of Vaccinia Virus and Its Origin. London: Heineman, 1981. Written as a response to Peter Razzell’s biography, this history takes the view that Jenner was the true originator of vaccination with the cowpox vaccine.
  • citation-type="booksimple"

    xlink:type="simple">Cartwright, Frederick, and Michael D. Biddiss. Disease and History. 2d ed. Stroud, England: Sutton, 2000. A general perspective on how diseases such as smallpox have influenced history. A chapter deals specifically with smallpox.
  • citation-type="booksimple"

    xlink:type="simple">Dixon, C. W. Smallpox. Boston: Little, Brown, 1962. Presents the clinical and public health aspects of smallpox. Very technical treatment of the clinical manifestations of smallpox, its history, and its control when global smallpox eradication programs were still in their infancy. Photographs.
  • citation-type="booksimple"

    xlink:type="simple">Fenner, Frank, et al. Smallpox and Its Eradication. Geneva: World Health Organization, 1988. The definitive history (in approximately 1,500 pages) of the campaign to eliminate smallpox by scientists involved in the project. Well-written reference on smallpox and public health campaigns.
  • citation-type="booksimple"

    xlink:type="simple">Fox, Jeffrey. “WHO Assembly to Consider Smallpox Destruction.” American Society for Microbiology News 60 (April, 1994): 183-186. Discusses the plans to destroy smallpox stocks and the arguments for and against the plans.
  • citation-type="booksimple"

    xlink:type="simple">Razzell, Peter. Edward Jenner’s Cowpox Vaccine: The History of a Medical Myth. Firle, England: Caliban Books, 1977. A biography that disputes Jenner’s responsibility for originating vaccination. Razzell proposes that Jenner was simply practicing variolation with a mild form of smallpox virus. For the opposing view, see Derrick Baxby’s biography.
  • citation-type="booksimple"

    xlink:type="simple">Tucker, Jonathan B. Scourge: The Once and Future Threat of Smallpox. New York: Grove Press, 2001. An accessible and engrossing look at the history of smallpox, the attempts to eliminate its naturally occurring form, and the debate over whether the virus stocks should be destroyed.
  • citation-type="booksimple"

    xlink:type="simple">Zinsser, Hans. Rats, Lice, and History. Boston: Little, Brown, 1935. A somewhat rambling treatise on infectious disease. The first nine chapters give a good description of the ecological relationships between disease-causing agents and humans.

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