The World of Smallpox

Smallpox is caused by a highly contagious virus (Variola major) which is spread through person-to-person contact.   It is not related to chickenpox.  Early symptoms were high fever and fatigue, followed by a characteristic rash that appeared two to three days later, particularly on the face, arms and legs. The resulting spots filled with clear fluid and pus, which then formed a crust that eventually dried up and fell off. The virus had an incubation period of 7 to 17 days after exposure. A person only became infectious once the fever developed. Although the most infectious period was during the first week of illness, a sick person remained contagious until the last scabs fell off.

Fear, sickness, and death

Anyone who survived the disease had lifelong immunity from subsequent smallpox outbreaks. Many victims were infants or young children who were unprotected during their first exposure to smallpox. Long term complications included pitted skin and scarring particularly of the face and blindness. Depending on the severity of the disease, other complications could include encephalitis, toxemia, and extensive internal bleeding. Some forms of smallpox (e.g., malignant and hemorrhagic smallpox) were nearly always fatal.

With a fatality rate of 30%, smallpox has killed millions of people over the last 3,000 years and abruptly altered history. Ramses V of Egypt (1145 BCE) was a notable early victim. Elsewhere, European royal dynastic succession was affected by heirs surviving (or not) the disease. Edward VI, son of the English king Henry VIII, died from complications of smallpox; the monarchy ultimately passed to his half-sister, Elizabeth I.  Native Amerindian and Australian aboriginal populations suffered devasting losses in the sixteenth, seventeenth, and eighteenth centuries. In Europe, smallpox was the leading cause of death in the eighteenth century. As author Jonathan Tucker notes, “smallpox was a democratic scourge, afflicting people of every race, class, and social position."  (Tucker 12)

There is no cure.


Smallpox recognition card

Dr. Larry Brilliant shows a picture of a child with smallpox to a villager in India. (1973)

Hope through vaccination

Prior to the discovery of the smallpox vaccine, quarantine was the most effective mean of combatting the disease. In Asia, beginning around 1000 BCE, people began to experiment with ways to make themselves immune to smallpox. One method was variolisation or inoculation in which a person was inoculated with a small amount of live smallpox virus taken from the scabs or pus of ill patients who had a mild form of the disease. Such inoculations reduced the fatality rate from 30 percent to about 1 percent.  (Tucker 15)  However, these methods carried the risk that the patient would die or become seriously ill with smallpox.

In 1796, the English physician, Edward Jenner, discovered a safer way to prevent people from getting the virus. He used an inoculation of cowpox (a virus similar to smallpox but much milder and transferable from animal to human) which induced immunity against smallpox. The first vaccinations in England were given by arm-to-arm passage, then the vaccine liquid travelled through scabs or threads steeped in vaccine. During the 20th century, instruments were perfected to administer the vaccine (vaccinostyles, rotary lancet, jet injector, bifurcated needle) and a better way to transport the delivery of the vaccine was found using freeze-drying technology.

While pre-emptive vaccination of uninfected populations could prevent the disease, it was soon determined that smallpox vaccination could also be effective if it was given during a period of up to four days after a person had been exposed to the virus. This became a key factor in the smallpox eradication efforts of the 20th century.


Vaccinostyle with interchangeable needle tips

Vaccinostyle with interchangeable needle tips. (1972)

Jet injector

A health care workers uses a jet injector. (1972)

Bifurcated needle

A patient is vaccinated using a a bifurcated needle. (1972)

The WHO Eradication Program

Because the sociological, political, economic, and health effects of smallpox were devastating, the idea of a global campaign to eradicate smallpox began to circulate among various national and international organizations and communities. The logical entity to take up this challenge was the World Health Organization (WHO), founded in 1948 as one of the specialized agencies of the United Nations.  In the early 1950s, the initiative was considered too ambitious and too costly.  However, support for global eradication was increasing.

In 1958, the Eleventh World Health Assembly accepted a resolution to determine the costs of such a program.  A report was issued the following year which estimated the cost of a global smallpox eradication program to be $0.10 per person or $97,742.900.  (Fenner 369)  Despite the huge discrepancy between the projected costs and WHO's budget, a unanimous decision was made by the Twelth World Health Assembly to move ahead with the project.

By 1966, although 24 countries were already free from smallpox, thanks to their own mass vaccination campaigns, the disease was still endemic in several regions of the developing world including Africa, the Indian subcontinent, Southwest Asia, Indonesia, and Brazil.   The total number of smallpox cases was estimated at 10 million to 15 million annually, with 2 million deaths.  (Tucker 62) That year the Nineteenth World Health Assembly adopted a resolution proposing intensification of the programme to eradicate smallpox, with the hope that the disease would be eliminated from the world within ten years. The smallpox resolution passed by two votes at the World Health Assembly, the closest margin in the history of the WHO.  (Tucker 58)  

With this new intensive effort, WHO epidemiological teams employed a combined strategy of mass vaccination campaigns (begun in 1958) with active searches and containment procedures, i.e., quarantine (begun in 1967). The teams were sent to endemic areas in Africa and the Indian Subcontinent. Their effectiveness can be seen on the map which shows the shrinking boundaries of smallpox outbreaks.

By 1972, an additional 25 countries were declared smallpox free.  The last foci disappeared during the following years until the last known natural case in Somalia in 1977. The world was finally declared smallpox free in 1980.


Smallpox target zero

Cover of World Health (October 1972)

Smallpox endemic countries, 1964 - 1975

Countries with endemic smallpox in 1964, 1972, and 1975.

System for identifying and managing a suspected or confirm case of smallpox

Ideally, this is how an outbreak of smallpox should be handled. (n.d.)

India Engages the Pandemic