Third plague pandemic

The third plague pandemic was a major plague pandemic that began in Yunnan, China, in 1855. Its name refers to its status as the third of at least three known major pandemics caused by the spread of the bacterium Yersinia pestis. This episode of bubonic plague spread to all inhabited continents, and ultimately led to at least 15 million deaths worldwide, including 10-12 million in British Raj India and 2.2 million in China. Though it is estimated to have killed fewer people than the second plague pandemic (and possibly the first), the third plague pandemic had one of the highest death tolls among pandemics in human history.

According to the World Health Organization, the pandemic was considered active until 1960, when worldwide casualties dropped below 200 per year. Plague deaths have continued at a lower level ever since, as plague persists in enzootic reservoirs across Asia, Africa, South America, and the western United States.

The first plague pandemic began with the Plague of Justinian, which ravaged the Byzantine Empire and surrounding areas in 541 and 542; the pandemic persisted in successive waves until the middle of the 8th century. The second began with the Black Death, which killed at least one third of Europe's population in a series of expanding waves of infection from 1346 to 1353; this pandemic recurred regularly until the 19th century.

The plague which spread from Yunnan along China's Southeast Coast and across the world manifested almost exclusively as bubonic plague, with documentation of incidental pneumonic and septicemic forms. It was carried around the world through ocean-going trade, through transporting infected persons, rats, and cargoes harboring fleas.

Historians of the late-Qing plague epidemics generally include the Manchurian plague epidemic of 1910-11, which killed between 45,000-60,000 people, as defined within the third pandemic's scope. The pneumonic Manchurian plague epidemic was geographically, ecologically, genetically, and epidemiologically distinct from the bubonic plague which spread globally from Southern China. It spread throughout the region of Manchuria, reaching Vladivostok and Beijing (which was connected to Manchuria by the Imperial Chinese Railway), but not far beyond due to port and railway closures as well as preventive medical protocols.