Figure 1.

Distribution characteristics of five natural plague foci in China in this study. (A) Represents Plague Focus A, major hosts are Apodemus chevrieri and Eothenomys miletus, humans are infected by Yersinia pestis occasionally, and the area is filled with pink; (B) represents Plague Focus B, major host is Himalayan marmot, plague epidemic among animals is widespread and often affects human beings, and is marked in red; (C) represents Plague Focus C, major host is Rattus flavipectus, human bubonic plague epidemic had happened historically, and the area is marked in pink; (D) represents Plague Focus D with Microtus brandti as the major host; (E) represents Plague Focus E, and major host is Microtus fuscus. Both D and E are filled with green because cases of human infection have never been observed in the two areas.