Challenge #14 Stumper Between 1520 and 1570 the population of Central Mexico was reduced from 30 million to 3 million. The culprit was a disease caused by a virulent micro-organism introduced by Spaniards who arrived in Mexico with Cortes. Four hundred years later, in the mid 1960's, a vaccine became available to control the disease through immunization. This very infective organism still exists in many parts of the world including the US. It is able to survive only in humans, and passes from person to person in fine, airborne droplets. What is it? Answer: The measles (rubeola) virus, Briareus morbillorum. Correct answer received from Rhi, Beth Bemis