ABSTRACT
Three stories are outlined in this chapter: the history of smallpox as a severe and recurrent scourge of life all over the world; the triumphant story of vaccination and the complete global eradication of smallpox as a clinical disease; and the ongoing role of smallpox as a potential biologic weapon of mass destruction. The chapter begins with a description of the disease itself, including the high rate of infection – up to 90% after exposure; the very high case fatality rate of 30–60%; and the terrible sequelae of scars and blindness. The development of techniques to prevent smallpox is described from inoculation with deliberate exposure to tiny doses of fluid from smallpox lesions with hope that immunity would occur without severe illness, to vaccination, developed by Edward Jenner in the early 1800s. With inoculation and then vaccination, smallpox came to be a much less common part of life in developed countries, but major third-world outbreaks continued into the mid-1900s.
The history of smallpox eradication is described beginning with identification of the characteristics of the smallpox virus, Variola major, which made eradication a possibility. The virus was found to be remarkably stable with little spontaneous mutation over time and humans were identified as the only hosts. The existing vaccine, available in a freeze-dried form, was safe and highly effective. The remarkable course of the Smallpox Eradication Program, funded by the World Health Organization (WHO) in 1966, is described. Dr. D. A. Henderson, a young epidemiologist at the US Centers for Disease Control (CDC), led the program using a two-component strategy: mass vaccination of all available subjects; and isolation of victims and vaccination of all their known contacts, an approach now known as ring vaccination. Remarkably, using local teams in all countries with persistent smallpox outbreaks, Henderson’s program was successful: the last case of naturally acquired smallpox occurred in October 1977 and eradication was ultimately declared successful at the end of 1979. In 1980, the WHO mandated that only the CDC in the United States and the Research Institute for Viral Preparations in the USSR be allowed to retain a limited supply of the virus in high-security laboratories.
These two smallpox reserves introduce the final part of the smallpox story: smallpox as a potential biologic weapon. Since 1980, the general population has not been vaccinated against smallpox, which means that release of the smallpox virus could have devastating consequences for our now unprotected world population. The chapter outlines the global history of bioweapons development and the elimination of all US offensive biological weapons in 1969. Adoption of the Biological and Toxin Weapons Convention in 1972 supposedly ended the global development of biological weapons of mass destruction (WMD), but stockpiling of biologic WMDs has been suspected ever since. The 9/11/2001 terrorist attack on the United States precipitated a complete overhaul and escalation of the American biodefense program, with smallpox designated a Class A biologic weapon. Despite its complete eradication in 1980, smallpox is still considered a first-line potential biologic WMD.
