An ounce of prevention

Crises of infectious diseases are becoming more common. The world should be better prepared. One of the sobering lessons of the Ebola crisis was how ill-prepared the world was for such a deadly disease. It is terrifying to reflect on how the virus’s advance was halted in the teeming city of Lagos thanks only to the heroism of a single doctor and because the place just happened to have the expertise needed to trace all of the first victim’s contacts. Today the world is facing a worrying outbreak of Zika virus, adding to a growing list of diseases that includes SARS, MERS and bird flu. This is the new normal. New infectious diseases are becoming more common. With more people on the planet, more roads and flights connecting everyone, and greater contact between humans and animals, this is only to be expected. Over half of the 1,400 known human pathogens have their...