How microbes have destroyed civilisations in catastrophic biological events

A flea infected with Y. pestis: The most devastating enemy the Romans ever faced was Yersinia pestis, the bacterium that causes bubonic plague and that has been the agent of three historic pandemics, including the medieval Black Death. Photo: Wikimedia Commons

Bill Gates is worried. The tech entrepreneur and philanthropist has been using his megaphone to warn us of the catastrophic risk posed by infectious diseases.Â

In the Western world, where mortality from lethal germs has mostly receded into the background, the burden of infectious disease can seem like someone else’s problem.