Smallpox eradication
Smallpox eradication refers to the successful global effort to eliminate the infectious disease smallpox, culminating in an announcement by the World Health Organization (WHO) on October 26, 1979. This landmark achievement marked the first time in history that medical science eradicated an infectious disease, a process rooted in the realization that humans are the only hosts for the smallpox virus. The disease has ancient origins, with evidence suggesting its presence as far back as the twelfth century BCE in Egypt. A significant factor in smallpox's transmission was its introduction to the Americas during European conquests, leading to devastating impacts on indigenous populations.
Efforts to combat smallpox began with variolation techniques in China and evolved with Edward Jenner's development of vaccination in the late 18th century. By the mid-20th century, systematic vaccination efforts led to the disease's elimination in the United States by 1949, setting the stage for a global eradication campaign initiated in 1967. This campaign focused on detecting and containing outbreaks rather than achieving universal vaccination, a strategy that proved effective.
Despite the success of smallpox eradication, questions remain about the future implications of eliminating a viral species, particularly concerns regarding the potential emergence of other infectious agents. As of now, only a few laboratory stocks of the smallpox virus exist, and debates continue about their fate, reflecting ongoing considerations of public health and safety in the global community.
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Smallpox eradication
THE EVENT: Medical science’s elimination of the infectious disease smallpox worldwide
DATE: Announced on October 26, 1979
The eradication of smallpox by scientists working under the auspices of the World Health Organization represented the first time medical science was able to eliminate an infectious disease. Concern remains that eradication of a viral species may create an environmental niche into which other agents may enter.
The precise origins of smallpox are unknown, but it clearly was a disease of antiquity. Pharaoh Ramses V of Egypt (twelfth century BCE) reportedly died of a disease resembling smallpox. The disease was prevalent in China and India for at least fifteen centuries before its appearance in the Middle East in the sixth century.Crusaders returning from the Middle East spread smallpox throughout Europe during the twelfth and thirteenth centuries, and the disease was introduced to the Western Hemisphere by the Spanish under Hernán Cortés (1520). Reportedly, more than three million Aztecs died from smallpox within two years, opening Mexico to Spanish invaders. It is estimated that the annual death rate from smallpox in Europe during this period approached 400,000; those who survived the disease were often disfigured by scarring.
The first attempts at immunization against the disease were practiced by the Chinese. In a process called variolation, dried powder from smallpox crusts (the scabs that formed over the lesions caused by the disease) was inhaled. The procedure was taken to the Middle East during the seventeenth or eighteenth centuries, probably by Arab traders, where Lady Mary Wortley Montagu, wife of the British ambassador to the Ottoman Empire, became aware of the practice. Lady Montagu, herself a scarred survivor of the disease, had her young son successfully variolated in 1718. The British royal family soon heard of the practice and introduced it into England several years later.
While variolation was useful in producing immunization against smallpox, it remained a difficult and dangerous procedure. An alternative had long been practiced by British dairy farmers: the inoculation of people with material taken from the lesions that developed on the udders of cows infected with cowpox. In the 1790’s, Edward Jenner, an English country physician, became aware of the practice and tested the procedure on himself and several volunteers. With the publication of his work An Inquiry into the Causes and Effects of the Variolae Vaccinae (1798), the use of vaccination quickly spread through both Europe and the Americas. Though smallpox was not eliminated, its incidence declined steadily over the next century. Owing to widespread, systematic vaccination, it was eliminated from the United States by 1949.
The key to global eradication of smallpox was based on a characteristic of the that made it unlike most viral diseases: Humans represent the only for smallpox. Because both vaccination and recovery from infection result in lifelong immunity, once the chain of infection was disrupted, smallpox would cease to be an epidemic disease.
In 1950 a program was developed to eradicate smallpox in the Western Hemisphere through widespread immunization among susceptible populations. By 1958 the disease had been eradicated in most of the Americas, lending credibility to a Soviet proposal for the global elimination of the disease. Beginning in 1965 a program was developed to meet that goal. The program was based on the realization that a goal of immunizing 100 percent of the world’s was unrealistic. Rather, the goal had to be to detect and contain local outbreaks of disease, breaking any chain of transmission. Once the disease could no longer spread beyond local borders, any outbreak would die out.
In 1967 the incidence of smallpox approached an estimated ten to fifteen million cases in forty-six countries. Within ten years, however, the disease virtually ceased to exist; the last reported natural case was that of a young Somali in 1977. In 1978 a single fatal laboratory-associated infection occurred at the Birmingham University Medical School in Great Britain, in which a medical photographer was infected by a virus being studied in an adjacent laboratory. On October 26, 1979, the World Health Organization (WHO) announced the global eradication of the disease.
Following the eradication of smallpox, the issue was raised as to whether all existing laboratory stocks of the virus should be destroyed, which would mean the deliberate destruction of a species. By the mid-1990s, the only remaining virus stocks known to exist were stored at the Centers for Disease Control and Prevention in Atlanta, Georgia, and the Institute for Viral Preparations in Moscow, Russia (these were later moved to the State Research Center of Virology and Biotechnology VECTOR in Koltsovo, Novosibirsk, Russia). As of 2024, they remain the only existing samples of the disease. The deoxyribonucleic acid (DNA) genomes of several species of the virus were sequenced, and many argued that the remaining stocks of smallpox should be destroyed. Others offered arguments to the contrary, however, and after years of debate, WHO in 2002 took the stance that the remaining stocks should not be destroyed. Scientists continued to disagree on this topic into the 2020s.
Some have expressed concern that with the elimination of a viral species, an environmental niche may be created that could provide a means for other viruses to enter the human population. Widespread infection by smallpox, in addition to general use of vaccination, created a population resistant to infection by most other forms of poxviruses. Whereas smallpox was species-specific in only infecting humans, other viruses such as monkeypox and the whitepox viruses can infect a variety of primates, including humans. These viruses are neither as disfiguring nor as deadly as smallpox, and they are not transmitted as readily as smallpox, but the combination of poverty and social upheaval in the world’s developing countries could conceivably facilitate the spread of such diseases among human populations.
Bibliography
Behbehani, Abbas M. The Smallpox Story: In Words and Pictures. Kansas City: University of Kansas Medical Center, 1988.
Fenner, Frank, et al. Smallpox and Its Eradication. Geneva: World Health Organization, 1988.
"History of Smallpox." Centers for Disease Control and Prevention, 1 May 2024, www.cdc.gov/smallpox/history/history.html. Accessed 22 July 2024.
Koplow, David. Smallpox: The Fight to Eradicate a Global Scourge. Berkeley: University of California Press, 2003.
Tucker, Jonathan B. Scourge: The Once and Future Threat of Smallpox. New York: Grove Press, 2001.