Smallpox

Abstract

It is estimated that smallpox arose in the human population either 16,000 or 68,000 years ago from a rodent source, possibly as two different diseases. The virus mutated to greater pathogenicity in the sixteenth and seventeenth centuries, with epidemics in most urban centers of the world. It was a disease that was endemic in European and Asian populations, but extremely virulent among the non-immune native populations of the New World. Ninety percent of the American Indians died as a result of smallpox, leading to the easy colonization of the American continent by the Spaniards, and later by other European settlers. The decimation of the Amerindians led to the introduction of slavery to work the silver and gold mines. Smallpox found an immune “virgin population” in the Americas, and in other isolated populations. Reasons for this difference in response to the infection are discussed. Smallpox is the first human infectious viral disease to have been eradicated from the earth; its eradication is a fascinating history—from variolation to development of a vaccine in the eighteenth century to complete elimination in 1977.