The World Health Organization launched its smallpox eradication program in 1959. Progress was slow in the ensuing years but success came after the organization intensified its efforts in 1967. Thirteen years later WHO declared the world free of smallpox.
Smallpox, or variola, plagued humanity as one of the world’s major epidemic diseases for about three thousand years. Without an effective, disease-specific treatment for the infection, up to 25 percent of individuals affected by variola major, the deadlier form of the smallpox virus, succumbed to the infection. Survivors acquired lifelong immunity and were easily recognized by the disfiguring pockmarks on their faces.
Early attempts at disease prevention occurred in China, India, and Turkey, where inoculation with small amounts of material obtained from smallpox pustules provided lifelong immunity. This procedure, known as variolation, became popular in Europe after its introduction to the West by Mary Wortley Montagu
Not until 1796 was there a major breakthrough in smallpox prevention. Edward Jenner
The World Health Organization (WHO), headquartered in Geneva, Switzerland, is an agency of the United Nations. In its pursuit of global health, the prevention and control of epidemic diseases became its main mission. In 1953, WHO’s director general, Brock Chisholm, proposed to eradicate smallpox around the world. His proposal, initially rejected, was brought back to the table by the Soviet Union’s deputy minister of health Viktor M. Zhdanov at the 1958 World Health Assembly, WHO’s governing forum. One year later WHO launched its program for the global eradication of smallpox.
At the time of Zhdanov’s proposal, smallpox was endemic in fifty-nine countries and territories in Africa, Asia, and South America, where 59 percent of the world’s population resided. The 1959 Global Eradication Programme’s
Vaccinations of large populations continued to be an essential element of the intensified eradication program, but significant efforts also were made to detect and contain smallpox outbreaks. WHO, further recognizing that support of active research would enhance chances of global smallpox eradication, made additional funds available. WHO also encouraged endemic countries to make their own vaccine. Reference laboratories in the Netherlands and Canada provided quality control of both donated and locally produced vaccines.
Mass vaccination was facilitated by the arrival of the jet injector and the bifurcated needle. The jet injector, initially marketed for the administration of a variety of drugs, was adapted for smallpox vaccination in 1962. The device made it possible to vaccinate one thousand people per hour. An even larger technological step was the development of the bifurcated needle, which required the use of less vaccine. Inexperienced health workers could learn its application in as little as fifteen minutes. The bifurcated needle was used very successfully in eradication programs throughout Africa.
A Handbook for Smallpox Eradication Programmes in Endemic Areas
In time it became clear that it was not necessary to vaccinate 80 percent of the target population to eradicate the disease. Smallpox only affected humans and had an incubation period of about fourteen days. This meant that any individual who had been in contact with smallpox would not develop signs of the disease nor become infectious for two weeks. This time period created a window of opportunity for the health care teams and allowed for the isolation of affected individuals, tracking of the infection’s source, and the vaccination of contact people. This approach suppressed potential smallpox outbreaks, but it required extensive reporting systems that could quickly detect new cases and cover large geographic areas. The best sources of reliable information were found in schools and marketplaces. In densely populated areas, however, careful village-to-village and house-to-house inquiries were needed to identify all smallpox cases.
Brazil, the only South American country with endemic smallpox at the time of the intensified eradication program, saw its last cases of smallpox in April of 1971. In Asia, Nepal and India reported their last cases in the spring of 1975. Bangladesh followed in October. Bangladesh’s three-year-old Rahima Banu entered medical history as the last patient in the world to have been naturally infected with variola major.
Variola minor, the milder form of the smallpox infection, with a mortality rate of less than one percent, persevered in Ethiopia until 1976. The last case of variola minor was reported in Somalia on October 26, 1977. Ali Maow Maalin, a health care worker, was the last person to have been infected with naturally occurring variola minor.
WHO determined that two years without disease recurrence was appropriate to certify that a country was free of smallpox. A tight surveillance system was established and, in 1980 the Global Commission for the Certification of Smallpox Eradication announced officially that the world was free of naturally occurring smallpox.
Routine smallpox vaccinations ceased around the world in 1984 because of the success of the eradication program. The triumph over smallpox is considered one of the greatest World Health Organization accomplishments, but the specter of another variola outbreak remains. Mislabeled or unregistered frozen vials of smallpox may linger in unsuspecting laboratories, and rogue nations could be keeping the virus in their weapons arsenals. The possible malevolent distribution of the smallpox virus through a bioterrorist attack cannot be ignored. A resurgence of smallpox would be devastating, since a large part of the world’s population is no longer immune to the virus.
Although routine vaccinations of the general population ended, two separate cases in the United Kingdom underline how important it is to maintain adequate vaccination of personnel who work in research institutions harboring the virus. In 1973, a young woman fell ill after observing a laboratory worker manipulate the smallpox virus at the London School of Hygiene and Tropical Medicine. She spread the disease to three other people; two of them died. In 1978, a photographer, working one floor above the microbiology laboratory at the University of Birmingham, died after contracting smallpox. WHO has repeatedly recommended the destruction of all smallpox viruses, but some scientists argue that additional research is needed before all samples of the virus can be destroyed.
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Arita, Isao. “Smallpox Vaccine and Its Stockpile in 2005.” Lancet Infectious Diseases (October, 2005): 647-652. Discusses the use of smallpox vaccine in case of a bioterrorist attack. -
Baciu, Alina, et al., eds. The Smallpox Vaccination Program: Public Health in an Age of Terrorism. Washington, D.C.: National Academies Press, 2005. Discusses the potential threat of variola as a biological weapon by global terrorists. -
Fenner, Frank, et al. Smallpox and Its Eradication. Geneva: World Health Organization, 1988. Contains extensive historical and medical information regarding smallpox and provides details about efforts by WHO to free the world of smallpox. Contains photographs of individuals affected by smallpox. -
Koplow, David. Smallpox: The Fight to Eradicate a Global Scourge. Berkeley: University of California Press, 2003. Gives historical background pertaining to variola major and minor and presents arguments for and against the extermination of smallpox. -
Needham, Cynthia A., and Richard Canning. Global Disease Eradication: The Race for the Last Child. Washington, D.C.: ASM Press, 2003. Discusses smallpox eradication in the context of the attempted eradication of other global infectious diseases that continue to plague humankind.
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