Yesinia pestis causes plague, famously known as the Black Death after it caused an estimated 50 million deaths throughout Europe, Africa, and Asia in the 1300s. Depending on the route of infection, plague can occur as a bubonic, septicaemic, or pneumonic form of infection. It is lethal in 30-60% of untreated cases, but with timely diagnosis and antibiotic treatment, nearly all patients can be cured.

Y. pestis is on the list of Select Agents and Toxins that have the potential to cause severe threat to public health and safety. In the US the Center for Disease Control (CDC) monitors the use and transfer of these agents and they are subject to rules published by the Department of Health and Human Services (DHHS), and the Department of Agriculture (USDA).