Global Eradication of Smallpox

Smallpox is an acute contagious disease caused by variola virus, a member of the orthopoxvirus family. Smallpox, which is believed to have originated over 3.000 years ago in India or Egypt, is one of the most devastating diseases known to humanity. For centuries, repeated epidemics swept across continents, decimating populations and changing the course of history.

In some ancient cultures, smallpox was such a major killer of infants that custom forbade the naming of a newborn until the infant had caught the disease and proved it would survive. Smallpox killed Queen Mary II of England, Emperor Joseph I of Austria, King Luis I of Spain, Tsar Peter II of Russia, Queen Ulrika Elenora of Sweden and King Louis XV of France.

The disease, for which no effective treatment was ever developed, killed as many as 30% of those infected. Between 65–80% of survivors were marked with deep pitted scars (pockmarks), most prominent on the face. Blindness was another complication. In 18th century Europe, a third of all reported cases of blindness was due to smallpox. In a survey conducted in Viet Nam in 1898, 95% of adolescent children were pockmarked and nine-tenths of all blindness was ascribed to smallpox.

As late as the 18th century, smallpox killed every 10th child born in Sweden and France. During the same century, every 7th child born in Russia died from smallpox. Edward Jenner's demonstration, in 1798, that inoculation with cowpox could protect against smallpox brought the first hope that the disease could be controlled.

In the early 1950s – 150 years after the introduction of vaccination – an estimated 50 million cases of smallpox occurred in the world each year, a figure which fell to around 10–15 million by 1967 because of vaccination. In 1967, when WHO launched an intensified plan to eradicate smallpox, the "ancient scourge" threatened 60% of the world's population, killed every fourth victim, scarred or blinded most survivors, and eluded any form of treatment.

Mass vaccination programs were successful in many Western countries; however, a different approach was taken in developing countries. This approach was known as surveillance and containment. Surveillance was aided by extensive house-to-house searches and rewards offered for persons reporting smallpox cases. Containment measures included ring vaccination and isolation of cases and contacts. Hospitals played a major role in transmission in a number of smallpox outbreaks.

Through the success of the global eradication campaign, smallpox was finally pushed back to the horn of Africa and then to a single last natural case, which occurred in Somalia in 1977. Ali Maow Maalin (photo) had worked temporarily as a smallpox vaccinator but he had not been successfully vaccinated and on 22 October 1977 he contracted the disease after being exposed to two children with smallpox. He ultimately recovered from the disease.

A fatal laboratory-acquired case occurred in the United Kingdom in 1978. The global eradication of smallpox was certified, based on intense verification activities in countries, by a commission of eminent scientists on 9 December 1979 and subsequently endorsed by the World Health Assembly in 1980.

The WHO Orthopoxvirus Committees meeting in 1994 and 1999 have recommended that no one other than the two WHO collaborating centres in the United States and the Russian Federation may have in possession at one time more than 20% of the viral DNA for variola virus.

The World Health Organization is currently supporting several control programs and has not singled out another disease for eradication. The lessons learned from the smallpox campaign can be readily applied to other public health programs.

Link

The WHO factsheet on smallpox.

Stamp catalogue

Tunisia 16 October 1978

Up - Home

last revised: 14 February 2008