From plague bacteria’s perspective, humans and black rats are second-rate hosts because of their tendency to die quickly after the pathogen enters their bodies. Some other species, most notably great gerbils and marmots, both of which live in mountainous areas of Central Asia, have partial resistance to Yersinia pestis. Their bodies provide an environment where the bacteria can reproduce without killing the host. This means that while plague epidemics quickly burned out in human and rat populations, the pathogens could survive for centuries or even millennia in gerbils and marmots, before once
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