Black Rat (Plague Vector)

Timeline

1. c. -1000–500South Asian and West Asian trade corridors · South AsiaThe black rat spread from South Asia to West Asia and North Africa via grain storage and trade routes, becoming a common commensal rodent in ports and towns, laying the ecological foundation for the long-term circulation of the plague bacterium among rat populations.
2. 1100–1340Mediterranean and Black Sea ports · Italian PeninsulaThe black rat widely inhabited cargo holds, dockside warehouses, and crevices in city walls, traveling between Venice, Genoa, Constantinople, and Black Sea ports along the spice, textile, and grain trades; before 1340, a rodent migration corridor linking East Asia, Central Asia, and Western Europe had already formed.
3. 1340–1349Crimea–Mediterranean–Western Europe · CrimeaIn the mid-to-late 1340s, the plague bacterium erupted along Black Sea–Mediterranean trade routes: plague at the Crimean port of Caffa in 1347 spread by ship, and in 1348 it entered Western Europe via Sicily and Marseille. The black rat and its fleas were later confirmed by epidemiology as key links in the transmission chain; contemporaries knew only of 'rat infestations' and 'miasma,' but port rat densities overlapped highly with epidemic outbreak sites.
4. 1894Hong Kong · ChinaAfter Yersin discovered the plague bacterium in 1894, the black rat-flea-human transmission chain received scientific confirmation, enabling retrospective understanding of the ecological mechanisms of the 1340s pandemic and promoting port rat eradication and quarantine systems.