A visitor brings doom to an isolated tribe.

The article explores the history of diseases introduced by outsiders to the indigenous tribes of Peru. Topics discussed include the story of Marcelino Pinedo Cecilio and how his tribe saw 200 people dead after an anthropologist visited them and the eradication of half the population of the Aztec capital of Tenochtitlan after the arrival of Spanish conquistador Hernán Cortés and his smallpox-carrying troops.