Stefan Riedel, MD, PhD
Yersinia pestis is the causative agent of plague, an enzootic vectorborne disease usually infecting rodents (rats) and fleas. Humans can become infected after being bitten by fleas that have fed on infected rodents. In humans, the disease usually occurs in the form of bubonic plague. In rare cases, the infection spreads to the lungs via the bloodstream and causes secondary pneumonic plague. Person-to-person transmission has been described for pneumonic plague but is rare in primary bubonic plague. Bubonic plague can usually be treated successfully with antibiotics; however, pneumonic plague develops rapidly and carries a high fatality rate despite immediate treatment with antibiotics. Plague is also recognized as a potential agent of bioterrorism. It has been used, or considered for use, as a biologic weapon on several occasions. It is important for the medical community to be familiar with the epidemiology, diagnosis, and symptoms of plague so it can deliver an appropriate and calm response should the unthinkable happen.
In recent years, the fear about terrorist attacks with biological weapons has grown. Plague has been identified by the Centers for Disease Control and Prevention (CDC) as a category A organism (1). This third article in a series of papers addressing issues related to biological warfare and bioterrorism gives a concise overview of the role that plague has played in the past and present as a biological weapon. As outlined in the historical review of biological warfare (1,2), plague has been one of the most devastating epidemic diseases to mankind, second only to smallpox. Given the presence and availability of plague around the world, the capacity for mass production and aerosol dissemination, the high fatality rate of pneumonic plague, and the potential for rapid secondary spread, the potential use of plague as a biological weapon is of great concern.