Third plague pandemic

The bubonic plague was endemic in populations of infected ground rodents in Central Asia and was a known cause of death among the migrant and established human populations in that region for centuries. An influx of new people because of political conflicts and global trade led to the spread of the disease throughout the world from Asia to the rest of Europe, to reach Africa and the Americas.

A natural reservoir or nidus for plague is in western Yunnan and is still an ongoing health risk. The third pandemic of plague originated in the area after a rapid influx of Han Chinese to exploit the demand for minerals, primarily copper, in the second half of the 19th century.[9] By 1850, the population had exploded to over 7 million people. Increasing transportation throughout the region brought people in contact with plague-infected fleas, the primary vector between the yellow-breasted rat (Rattus flavipectus) and humans. People brought the fleas and rats back into growing urban areas, where small outbreaks sometimes reached epidemic proportions. The plague spread further and began to appear in the Pearl River delta, including Canton and Hong Kong. Although William McNeil and others believe the plague to have been brought from the interior to the coastal regions by troops returning from battles against the Muslim rebels, Benedict suggested evidence to favor the growing and lucrative opium trade, which began after about 1840.[9]

In the city of Canton, beginning in March 1894, the disease killed 80,000 people in a few weeks. Daily water-traffic with the nearby city of Hong Kong rapidly spread the plague. Within two months, after 100,000 deaths, the death rates dropped below epidemic rates, but the disease continued to be endemic in Hong Kong until 1929.[10]

The network of global shipping ensured the widespread distribution of the disease over the next few decades.[11][12][13][14] Recorded outbreaks included the following:

Each of the areas, as well as Great Britain, France, and other areas of Europe, continued to experience plague outbreaks and casualties until the 1960s, although extremely few of these occurred after 1950.[25] The last significant outbreak of plague associated with the pandemic occurred in Peru and Argentina in 1945.

Yersinia pestis isolated by Ricardo Jorge during the 1899 Porto plague outbreak

Researchers working in Asia during the "Third Pandemic" identified plague vectors and the plague bacillus. In 1894, in Hong Kong, Swiss-born French bacteriologist Alexandre Yersin isolated the responsible bacterium (Yersinia pestis, named for Yersin) and determined the common mode of transmission.[26] His discoveries led in time to modern treatment methods, including insecticides, the use of antibiotics and eventually plague vaccines. In 1898, French researcher Paul-Louis Simond demonstrated the role of fleas as a vector.

The disease is caused by a bacterium usually transmitted by the bite of fleas from an infected host, often a black rat. The bacteria are transferred from the blood of infected rats to flea (Xenopsylla cheopis). The bacillus multiplies in the stomach of the flea, blocking it. When the flea next bites a mammal, the consumed blood is regurgitated along with the bacillus into the bloodstream of the bitten animal. Any serious outbreak of plague in humans is preceded by an outbreak in the rodent population. During the outbreak, infected fleas that have lost their normal rodent hosts seek other sources of blood.[29]

The British colonial government in India pressed medical researcher Waldemar Haffkine to develop a plague vaccine. After three months of persistent work with a limited staff, a form for human trials was ready. On January 10, 1897, Haffkine tested it on himself. After the initial test was reported to the authorities, volunteers at the Byculla jail were used in a control test. All inoculated prisoners survived the epidemics, while seven inmates of the control group died. By the turn of the century, the number of inoculees in India alone reached four million. Haffkine was appointed the Director of the Plague Laboratory (now called the Haffkine Institute) in Bombay.[30]

In the early 1900s, despite the increasing knowledge of germ theory and the rapid growth of scientific communities around the prevention of major disease, there was little the international communities could do other than create standard protocols for how to deal with an outbreak of the plague.[31] In 1897 and 1903, two conventions were held known as International Sanitary Conferences; the first in Venice and the second in Paris, to help deal with threat of the new outbreaks of the bubonic plague. From these conventions was formed an international disease convention supervised by the Office International d'Hygiene Publique (OIHP) in Paris which would be one of the major predecessors of the League of Nations health organization.[31] From these conventions came the standard Protocols used in dealing with the bubonic plague throughout the early 1900s.[31] These protocols were often old fashioned and were generally summarized as the 3 "I's": Isolation, Incineration, and Inoculation. Isolation is a standard protocol of many modern disease outbreaks, but the usage of incineration was a protocol of disease control used most uniquely for dealing with the bubonic plague.[31] Burning was used often to deal with the Plague as it was believed to the be most effective way to eliminate strains of the disease from places inhabited by the infected.[31] But it was also a problematic technique as it led to the creation of many out-of-control fires that devastated communities, the most notable being the great fire in Honolulu which devastated the Chinatown community there.[31] Inoculation was the usage of newly invented plague vaccines, with some in India being recorded to have an efficacy of over 50%.[32]

In many instances, the third plague pandemic either revealed or exacerbated major social conflicts and racial inequalities.[31] Many of the ports infected during the plague were at the time British-held colonies. This meant that in these colonies the British Empire was responsible for most of the actions used to prevent the disease.[33] Because of this the British often ended up enforcing western hygiene and medical practices and radical quarantine measures in countries and provinces such as India, South Africa and Hong Kong. Many of these imposed western sanitary measures were new to these areas and caused natives fear and apprehension of the British government.

In India harsh quarantines were initially implemented by the British governments, leading to Indian resentment of quarantine measures.[33] In South Africa when the plague broke out in Cape Colony, the British government caused a large group of native South Africans to move out of a supposed slum into areas on the outskirts of the city, which many historians argue was a racially motivated move by white South Africans to segregate African-born South Africans in other parts of the city.[34] In Hong Kong the British enforced many locally unfamiliar medical practices, such as floating plague victims out on boats onto the water and cooling plague victims with ice, which scared many Chinese residents of Hong Kong and led to their migrating back to mainland China, which was even more badly affected by the plague.[35]

Another instance of social harm caused by the response to the plague is the great fire of Honolulu in 1900, which caused the Chinatown in Honolulu to be destroyed, rendering over 7,000 Chinese and Japanese residents homeless.[31] In America when the plague reached San Francisco, the medical board of the city implemented a strict quarantine of the entire Chinatown district after discovering only one case of the plague; this has led many to question whether this measure was motivated by racial bias among medical professionals, who may have believed Chinatown to be unsanitary and hence already infected by the plague.[36]

• Timeline of plague
  • British Raj India pandemics

Media related to Plague, third pandemic at Wikimedia Commons

• Visual Representations of the Third Plague Pandemic