Pneumonic Plague

Yersinia pestis, the agent of plague, is one of the most feared pathogens in human history. By some estimates, plague has killed up to 200 million people during three major pandemics. The first recorded pandemic was the Justinian plague, which originated in Africa and spread around the Mediterranean during the sixth century. The second occurred in Europe during the fourteenth and fifteenth centuries and is sometimes referred to as the Black Death. The third pandemic began in China in the nineteenth century, spread throughout India and Asia, and eventually reached the Americas and other continents. Between these pandemics, the disease has manifested itself in smaller periodic outbreaks. During the last 50 years, the worldwide annual number of human plague cases documented by the World Health Organization has ranged from about 200 to 6000. Plague remains a significant public health threat today, due to natural outbreaks of the disease, the emergence of antibiotic resistant strains, and its possible use as a biological weapon.