If your doctor suspects plague, he or she may look for the Yersinia pestis bacteria in samples taken from your:
- Buboes. If you have the swollen lymph nodes (buboes) characteristic of bubonic plague, a fluid sample can be taken from them with a needle.
- Blood. Yersinia pestis bacteria generally are present in your bloodstream only if you have septicemic plague.
- Lungs. To check for pneumonic plague, your doctor will take sputum or fluid from your airways using endoscopy — a thin, flexible tube inserted through your nose or mouth and down your throat.