FOR MOST OF US, pandemics were once the stuff of the distant past, relegated to dusty history books. Of course, today, we understand them so much better. We’ve seen first-hand the way they cause death and suffering, put huge numbers of people out of work, and tip societies all over the world into recessions and depressions. So it may be a surprise to find out that, in a number of instances, there has also been an unexpected side-effect of global disease outbreaks. Sometimes, they have...