Minor Changes Made 'Black Death' Germ Lethal

The bacterium Yersinia pestis has inflicted almost unimaginable misery upon humankind over the centuries, killing an estimated 200 million or more people and triggering horrific plagues in the 6th and 14th centuries. But this germ was not always particularly dangerous. Scientists said Tuesday that minor genetic changes that it underwent many centuries ago — adding a single gene that subsequently mutated — turned it from mild to murderous. Yersinia pestis caused two of the deadliest...

© La Voix de l'Amérique - mardi 30 juin 2015