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 distribution of the disease throughout the world.

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.[7] 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 after disputes between Han Chinese and Hui Muslim miners in the early 1850s erupted into a violent uprising, known as the Panthay Rebellion, which led to further displacements by troop movements and refugee migrations. The outbreak of the plague helped recruit people into the Taiping Rebellion. The plague began to appear in Guangxi and Guangdong provinces, Hainan Island, and then 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.[7]

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.[8]

Directions for searchers, Pune plague of 1897

The plague, which was brought from Hong Kong to British India, killed about one million in India.[9] It later also killed another 12.5 million there over the next thirty years. Almost all cases were bubonic, with only a very small percentage changing to pneumonic plague. (Orent, p. 185) The disease was initially seen in port cities, beginning with Bombay (now Mumbai), but later emerged in Poona (now Pune), Calcutta (now Kolkata), and Karachi (now in Pakistan). By 1899, the outbreak spread to smaller communities and rural areas in many regions of India. Overall, the impact of plague epidemics was greatest in western and northern India, in the provinces then designated as Bombay, Punjab, and the United Provinces; eastern and southern India were not as badly affected.

The colonial government's measures to control the disease included quarantine, isolation camps, travel restrictions, and the exclusion of India's traditional medical practices. Restrictions on the populations of the coastal cities were established by Special Plague Committees, with overreaching powers enforced by the British military. Indians found the measures culturally intrusive and generally repressive and tyrannical. The government's strategies of plague control underwent significant changes during 1898–1899. By then, the use of force in enforcing plague regulations had been shown to be counterproductive, and since the plague had spread to rural areas, enforcement in larger geographic areas would be impossible. British health officials then began to press for widespread vaccination by using Waldemar Haffkine’s plague vaccine, but the government stressed that inoculation was not compulsory. British authorities also authorized the inclusion of practitioners of indigenous systems of medicine into plague prevention programs.

Repressive government actions to control the plague led the Pune nationalists to criticize the government publicly. On 22 June 1897, the Chapekar brothers, young Pune Hindus, shot and killed Walter Charles Rand, an Indian Civil Services officer who was acting as Pune Special Plague Committee chairman, and his military escort, Lieutenant Ayerst. The action of the Chapekars was seen as terrorism.[10] The government also found the nationalist press to be guilty of incitement. The nationalist activist Bal Gangadhar Tilak was charged with sedition for his writings as editor of the newspaper Kesari and was sentenced to eighteen months of rigorous imprisonment.

Public reaction to the health measures enacted by the British Indian government ultimately revealed the political constraints of medical intervention in the country. The experiences were formative in the development of India's modern public health services.

The network of global shipping ensured the widespread distribution of the disease over the next few decades.[11][12][13] 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. The last significant outbreak of plague associated with the pandemic occurred in Peru and Argentina in 1945.

Y. 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. 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 the rat 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.

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 Haffkine Institute) in Bombay.[26]

• Timeline of plague
• Great Plague of London (1665)

• Visual Representations of the Third Plague Pandemic