Keywords: Yersinia pestis Bacteria.jpg en Scanning electron micrograph of Yersinia pestis which causes bubonic plague on proventricular spines of a Xenopsylla cheopis flea National Institute of Allergy and Infectious Diseases NIAID 2013-11-10 23 47 25 National Institutes of Health NIH National Institutes of Health NIH PD-USGov Uploaded with UploadWizard Yersinia pestis Xenopsylla cheopis |