Disease X and other unknowns

On February 26, 2003, Carlo Urbani, an infectious diseases specialist in the World Health Organization's (WHO's) country office in Vietnam, was called to the French Hospital in Hanoi to examine a grievously ill Chinese-American businessman. Johnny Chen had been admitted with severe breathing difficulties shortly after stepping off a flight from Hong Kong and was being nursed in intensive care, where x-rays revealed ominous shadows on his lungs.

A New Disease Is Testing Us for the Next Global Epidemic

The World Health Organization released its yearly list of infectious diseases that its experts think are especially high-risk. This year’s specimen included the pathogens that public health people consider the usual deadly suspects: Ebola and other hemorrhagic fevers, MERS and SARS, and mosquito-borne Zika and Rift Valley Fever. But there was also a novel entry: Disease X.