In 1894, Alexandre Yersin, a member of the French Colonial Health Service in Hong Kong isolated from buboes the causative bacillus that later was named Yersinia pestis in his honour. Yersin previously worked under Louis Pasteur and had isolated the diphtheria exotoxin with �mile Roux.

The last major plague pandemic began in China earlier in the year and lasted over a decade spreading from Hong Kong to port cities throughout the world.