A Hong Kong Epidemic Reveals the Plague Bacterium

In 1894, plague reached Hong Kong and turned a crowded trading port into a place of fear. People were dying while physicians argued about the disease and officials imposed emergency measures. Researchers arriving to study the outbreak faced more than an abstract scientific puzzle. They were working amid suffering, disrupted households and a colonial administration whose interventions were not automatically trusted by the population. A discovery would have to emerge from that unsettled environment.

Two investigators became especially associated with the search: the Japanese bacteriologist Kitasato Shibasaburō and the Swiss-born Alexandre Yersin, who had worked at the Institut Pasteur. They arrived in Hong Kong in June and carried out their investigations separately. The history of credit has been disputed because early reports and descriptions did not agree cleanly. Yersin’s observations became foundational to the identification of the organism now called Yersinia pestis, but the episode should not erase Kitasato’s simultaneous research.