| alexandre yersin (1863-1943): discoverer of the plague bacillus, explorer and agronomist. | alexandre yersin was born in french switzerland and later took french nationality. while a medical student he worked in paris with emile roux to discover the exotoxin produced by the diphtheria bacillus. two years after graduation, he left paris for french indochina where he was the first european to explore and map the central highlands of vietnam. as a member of the french colonial health service he was sent to hong kong in 1894 to investigate the outbreak of bubonic plague. he isolated from b ... | 2008 | 18653838 |