Editing Third plague pandemic (section)

==Disease research==
[[File:Preparações de Ricardo Jorge do bacilo da peste bubónica no Porto (1899) - fotografias de António Plácido da Costa (Museu de História da Medicina Maximiano Lemos, FMUP).png|thumb|right|''[[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.<ref name=Bramanti2019/>  His discoveries led in time to modern treatment methods, including [[insecticide]]s, the use of [[antibiotic]]s and eventually plague [[vaccine]]s. In 1898, French researcher [[Paul-Louis Simond]] demonstrated the role of fleas as a vector.<ref>Marc Simond, Margaret L. Godley, and Pierre D.E. Mouriquand (1998). “Paul-Louis Simond and his discovery of plague transmission by rat fleas: A centenary” J. Roy. Soc. Med., 91, 101-104.</ref>

The disease is caused by a bacterium usually transmitted by the bite of [[flea]]s 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.<ref>{{Cite book|title=Waldemar Mordekhaï Haffkine (1860–1930). Biographie intellectuelle|last=Hanhart|first=Joel|publisher=Honore Champion}}</ref>

The [[British Raj|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.<ref>{{Cite book|title=Waldemar Mordekhaï Haffkine (1860–1930). Biographie intellectuelle|last=Hanhart|first=Joel|publisher=Honore Champion|year=2016|location=Paris}}</ref>