- Smallpox is a contagious disease caused by the variola virus.
- Smallpox was the first disease to be eliminated from the world through public-health efforts and vaccination.
- Smallpox still poses a threat because existing laboratory strains may be used as biological weapons.
- Smallpox causes high fever, prostration, and a characteristic rash. The rash usually includes blister-like lesions that occur everywhere on the body.
- Approximately one-third of people with smallpox died from the disease. Survivors were scarred for life. If the eye was infected, blindness often resulted.
- There are new experimental medications that might be effective in smallpox, but these have not been tested in human cases since the disease has been eradicated.
- The vaccine contains a live virus called vaccinia. It is administered by dipping a pronged piece of metal into the vaccine and then pricking the skin.
- The vaccine has uncommon side effects that may be fatal, including infection of the heart and brain with the vaccinia strain. Serious side effects are more common with the initial vaccine and are uncommon with second doses.
- The vaccine is currently only given to selected military personnel and laboratory workers who handle the smallpox virus.
What is smallpox?
Smallpox is an infectious disease of the past that was eliminated by vaccination. The disease was caused by the variola virus, which spread from person to person. Affected people became very ill with a high fever and a characteristic rash. Up to one-third of people with smallpox died. Although the disease has been wiped out, samples of the virus still exist in high-security laboratories in the United States and Russia. This has led to concerns about use of the virus in biological warfare. For this reason, some military personnel are still vaccinated against smallpox.
What is the history of smallpox?
Smallpox is thought to have existed for more than 12,000 years. Evidence of infection can be found in mummies from ancient Egypt, including the mummy of Ramses V. Smallpox entered the New World in the 16th century, carried by European explorers and conquistadors. Because the aboriginal inhabitants had no immunity to the disease, smallpox often decimated native populations. There are even reports where infected blankets were used to intentionally infect Native American populations in the 18th century -- one of the early examples of biological warfare. During the 20th century, it is estimated that there were 300 million to 500 million deaths from smallpox worldwide, compared to 100 million from tuberculosis.
It was not until the end of the 18th century that an effective method of vaccination was developed. It was an English scientist named Edward Jenner who discovered it. Jenner observed that milkmaids often got a mild disease called cowpox and that this seemed to make them immune to smallpox. His vaccination strategy involved transferring the blister fluid from a person with cowpox to a person who had not yet had smallpox. This gave the susceptible person a cowpox infection (which was usually mild) and conveyed protection from smallpox. After a time, a virus similar to cowpox, called vaccinia, was substituted in the vaccine.
The last naturally occurring case of smallpox was in Somalia in 1977. In 1980, the World Health Organization (WHO) certified that the world was finally free of smallpox. Thus, smallpox was the first disease to be entirely eradicated. Campaigns are now under way to try to eliminate other diseases such as polio and measles.
The WHO has encouraged all member nations to destroy any remaining laboratory cultures of the virus. However, the rise of biological warfare technology led to concerns that smallpox could be weaponized and used in bioterrorism. Both the U.S. and Russia decided to retain their stockpiles in case they were needed to produce novel vaccines against a biological agent. This has understandably stirred up controversy. Supporters of retaining the cultures note that existing stocks of the virus have been used to develop and test new treatments and vaccines. The entire viral genome has been sequenced, leading to concerns that the virus may be recreated even if current stocks are destroyed.
Smallpox is a deadly disease and is on the list of potential biological weapons that are considered to pose the greatest threat to public health. Other agents on this list include anthrax, plague, smallpox, botulism, tularemia, and the viral hemorrhagic fevers, including Ebola and Marburg viruses.