Smallpox virus, an orthopoxvirus with a narrow host range confined to humans, was an important cause of morbidity and mortality in the world until recent times. The "pox" of smallpox is derived from the Latin word for "spotted" and refers to the raised bumps that appear on the face and body of an infected person. Eradication of the natural disease was completed in 1977 and the last human cases (laboratory infections) occurred in 1978. As of 2006, the World Health Organization (WHO) postponed the decision to destroy all smallpox stocks. The virus officially exists in only 2 laboratory repositories in the U.S. and Russia.
Appearance of human cases outside the laboratory would signal use of the virus as a biological weapon. Under natural conditions, the virus is transmitted by direct (face-to face) contact with an infected case, by fomites, and occasionally by aerosols. Smallpox virus is highly stable and retains infectivity for long periods outside of the host. A related virus, monkeypox, clinically resembles smallpox and causes sporadic human disease in West and Central Africa.
Smallpox is suspected to have originated in Africa, spreading to India and then China millennia ago. One of the earliest recorded outbreaks of smallpox was in the 2nd Century BCE during the war between Egypt and the Hittites. Pharaoh Rameses V's mummified body bore signs of smallpox. The first medical description of smallpox was written by Persian physician Al-Razi at the turn of the 10th Century titled Treatise on Smallpox and Measles. The viral agent spread throughout European cities and to the Americas by the 18th century. The illustrious list of notables who were victims of smallpox included Joseph I of Austria, Louis XV of France, William II of Orange, Emperor Gokomyo of Japan, Emperor Fu-lin of China and Mary II of England.
The first recorded instance of using smallpox as a biological weapon occurred on the North American continent during the French and Indian War. The outbreak of smallpox in Fort Pitt furnished the British with the idea of spreading smallpox to the Native Americans on the French side. In letter between Colonel Henry Bouquet and General Jeffery Amherst in June 1763, the British officer approved the plan. The British gave to the Native Americans blankets and handkerchiefs that contained the puss and scabs of British troops suffering from smallpox. Some historians claimed that even without the blankets and handkerchiefs, the smallpox virus would have eventually spread from the British camps to the Native Americans. The subsequent victory of the British when they attacked Fort Carillon (later renamed Fort Ticonderoga) is often attributed to General Amherst's success.
The fight to counter smallpox began with a process known as variolation, which exposes a healthy person to small samples of smallpox in order to induce a mild form of the disease so the person develops immunity. An early 11th Century record told of a Buddhist nun who ground smallpox scabs into powder, which was then inhaled by the healthy. This practice spread throughout China, India, and Turkey by the 18th century. The Ottoman court was widely known for using variolation. In 1796, Edward Jenner discovered that milkmaids who contracted cowpox, a milder pox virus, did not contract smallpox. He was the first to inoculate an 8 year old boy named James Phipps with cowpox. When later exposed to smallpox, the boy did not develop the disease. Despite initial doubts, the practice of vaccination spread during the 18th century. Famous advocates of inoculation included Thomas Jefferson and Napoleon Bonaparte.
The first vaccine of smallpox was licensed as the New York Board of Health Strain and named "Dyrax." The last US case arose in 1949 in Texas and resulted in 8 cases with 1 fatality. In 1967, the World Health Organization (WHO) initiated its campaign to eradicate smallpox, and 10 years later, thanks to a vast mobilization of funds for a global vaccination effort, the last natural case of variola minor infection occurred in Somalia (1977). On 8 May 1980, the WHO declared that smallpox had been eradicated.
Smallpox as a Weapon
Despite international success in eradicating smallpox, the variola virus remains a hazardous, Category A (CDC category) biological warfare agent. During World War II, the US and UK considered weaponizing smallpox, but with smallpox vaccines readily available, decided smallpox would be ineffective as a weapon.
During the Cold War, in 1974, the Soviet Union initiated Biopreparat, a civilian pharmaceutical company, as a front for the Soviet biological weapons program. Vladimir Pasechnik, a Soviet microbiologist who defected in 1989, provided information on the Soviet development of India 67 or India 1, a particularly virulent strain of smallpox, as a biological weapon. Scientists used embryonic chicken eggs to cultivate large amounts of smallpox virus. In addition, Dr. Ken Alibek (formerly Kanatjan Alikbekov), the former First Deputy Director of Biopreparat, reported the Soviet development of chimera viruses by inserting genetic material from other viruses into smallpox.
Reports suggested that the North Korean biological weapons program conducted research on smallpox as a possible biological agent. Widespread fears remain that the smallpox virus can be used as a weapon of bioterrorism as populations are no longer vaccinated against the virus.
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