The Lost City of the Monkey God

by Douglas Preston

Leishmaniasis has a long and terrible history with human beings, stretching back as far as human records exist and causing suffering and death for thousands of years. A few years ago, a hundred-million-year-old piece of Burmese amber was found to have trapped a sand fly that had sucked the blood of a reptile, most likely a dinosaur. Inside this sand fly, scientists discovered leishmania parasites, and in its proboscis, or sucking tube, they found reptilian blood cells mingled with the same parasites. Even dinosaurs got leishmaniasis. Leishmania has probably been around since the final breakup of the primordial continent known as Pangaea. As these ancient landmasses eventually drifted apart to become the Old and New Worlds, the populations of that sand fly ancestor were separated and continued to evolve independently, eventually giving rise to the two basic strains of the disease in the Old World and the New. At some point the disease made the leap from reptiles to mammals. (Modern reptiles still get leish, and there has been a medical debate over whether reptilian leish can be transmitted to humans; the answer is probably not.) Unlike many diseases that afflict human beings, leish was global from the very outset, and it was dreaded by our ancient ancestors in both hemispheres. Archaeologists have found leish parasites in Egyptian mummies dating back five thousand years, and in Peruvian mummies going back three thousand years. A description of leish appears in one of the ea...