"Montezuma's revenge," the notorious gastrointestinal scourge of tourists in Latin America, turns out to have been around for 2,500 years, according to a Medical College of Virginia pathologist who has been excavating ancient burial mounds in Chile. Because of the way the dead were buried -- in small chambers in the ground roofed over and sealed with sticks and dirt -- the bodies were mummified as the sun baked the graves. The result was that the bodies are in such good condition that simply by adding water the researchers could in theory restore them about to what they looked like at burial. "You could perform an autopsy on them just like you could on a modern person," Dr. Marvin Allison. In practice, he said, "we have rehydrated a hand, an arm, some internal organs." Examination of some of the bodies' gastrointestinal tracts revealed amoebas and bacteria that are common causes of intestinal distress associated with modern Latin American tourism. And the bugs were just as unpleasant as they are now. "As long as people were wandering around fishing and hunting and shepherding animals, the gastrointestinal diseases did not seen to be very common," said Allison. "But once they settled into a village environment, the health problems that arose from the contamination of the water supply and the close contact from living in a village probably gave rise to the start of today's epidemic-type gastrointestinal diseases." Allison also found that, contrary to previous belief, tuberculosis was a major health problem before the arrival of the white man. "Tuberculosis was definitely a disease native to the Americas before Columbus and the Vikings," he said. Indeed, he believes, it was one of the leading causes of death during the time he is studying. Allison's lung examinations have led him to the conclusion that "in rural Latin America today the [principal] cause of death has not changed in the last 3,000 years. It is still pneumonia and respiratory disease in general." Allison's work is supported in part by the National Geographic Society.