1863–1875 cholera pandemic

The fourth cholera pandemic of the 19th century began in the Ganges Delta of the Bengal region and traveled with Muslim pilgrims to Mecca. In its first year, the epidemic claimed 30,000 of 90,000 pilgrims. Cholera spread throughout the Middle East and was carried to the Russian Empire, Europe, Africa, and North America, in each case spreading via travelers from port cities and along inland waterways.

In 1866, there was a localized epidemic in the East End of London, primarily because the local section of the London sewerage system was still under construction and this region of London was experiencing overcrowding. The 1870s North American cholera outbreak spread from New Orleans via passengers along the Mississippi River and to ports on its tributaries.