General Information
Yersinia pestis was discovered in Hong Kong in 1894 by a Swiss physician Alexandre Yersin.

He linked Y. pestis to the bubonic plague, an epidemic that ravaged Europe during the 1300s.

The organism was isolated during a outbreak in Hong Kong

Taxonomy
Family: Enterobacteriaceae
It was formerly known as Pasteurella pestis.

The closest relative is the gastrointestinalpathogen Y. pseudotuberculosis and more distantly Y. enterocolytica

Natural habitats
Yersinia pestis interacts mainly with rodents such as rats and fleas (Xenopsylla cheopsis)

Through these carriers, Yersinia pestis is able to invade human cells and create diseases.

Clinical significance
Human Y. pestis infection takes three main forms, pneumonic, septicemic and bubonic plagues.

All three forms were responsible for a number of high-mortality epidemics troughout human history, including: the sixth century's Plague of Justinian, the Black Death, which accounted for the death of at least one-third of the European population between 1347 and 1353; and the 19th century's Third Pandemic

It has now been shown that these plagues probably originated in rodent populations in China.

Yersinia pestis infections must be diagnosed quickly due to the high virulence of these organisms.
Death from pneumonic plague can occur in as little as 24 hours after the first appearance of symptoms.