Alexandre Yersin

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Lore & Background

Yersin was born in 1863 in Aubonne, Switzerland, the youngest of three sons. His father, also named Alexandre, died of a cerebral hemorrhage shortly before Alexandre's birth. His mother, Fanny-Isaline-Emilie Moschell, raised their three children alone and settled in Morges, where she opened a school for girls. From 1883 to 1884 he studied medicine at Lausanne, then continued at Marburg and the Hôtel-Dieu de Paris (1884–1886). In 1886, Yersin entered Louis Pasteur's research laboratory at the École Normale Supérieure, by invitation of Émile Roux, and participated in the development of the anti-rabies serum. In 1888, he received his doctorate with a dissertation titled 'Étude sur le Développement du Tubercule Expérimental' and spent two months with Robert Koch in Germany. He obtained French nationality in 1888 and joined the Pasteur Institute in 1889 as Roux's collaborator, together discovering that Corynebacterium diphtheriae secreted a soluble toxin responsible for diphtheria. From 1890 to 1894, Yersin became a ship's doctor for the Messageries Maritimes shipping company on the Saigon-Manila line and then the Saigon-Haiphong line. He participated in one of the Auguste Pavie missions and led three expeditions across French Indochina. On 5 June 1894, he was sent by the French government to Hong Kong, where a plague outbreak had already caused 100,000 deaths. Just 15 days later, he isolated the plague bacillus, Yersinia pestis. He obtained specimens after bribing English sailors responsible for disposing of plague victims' bodies. In 1895 he returned to the Pasteur Institute in Paris and with Émile Roux, Albert Calmette and Amédée Borrel prepared the first anti-plague serum. He then returned to Indochina, installing a small laboratory at Nha Trang to manufacture the serum (which became a branch of the Pasteur Institute in 1905). Yersin tried the serum in Canton and Amoy in 1896, and in Bombay in 1897, with disappointing results. He founded the Institut Pasteur in Nha Trang in 1895, studied cattle breeding, and pioneered rubber tree cultivation (Hevea brasiliensis). He obtained a concession for an agricultural station at Suoi Dau in 1897, and opened a station at Hon Ba in 1915 where he acclimatized the quinine tree (Cinchona ledgeriana), enabling Indochina to meet its quinine needs during World War II. He also introduced cacao and coffee to Indochina. On 8 January 1902, Yersin was accredited as the first Headmaster of Hanoi Medical University. In 1934 he was nominated honorary director of the Pasteur Institute and a member of its Board of Administration. In Vietnam, he was affectionately called Ông Năm (Mr Nam/Five), a nickname due to his rank as a Colonel in the French army, with five horizontal lines in his army insignia.

Reader's Guide

Alexandre Yersin's significance lies in his dual role as a foundational figure in microbiology and a practical contributor to public health in Southeast Asia. His co-discovery of the diphtheria toxin with Émile Roux established the concept of bacterial exotoxins. Roux and Yersin studied filtrates of Corynebacterium diphtheriae through a porcelain filter, excluding the bacteria themselves. When injected into guinea pigs, the filtrates resulted in death, allowing them to claim a toxin was created by the bacterium. They also found the same toxin in urine from children sick with diphtheria shortly before their deaths. The diphtheria toxin was the first bacterial toxin discovered. His isolation of the plague bacillus in Hong Kong on 23 June 1894, though disputed with Kitasato Shibasaburō (who had discovered it on 14 June), led to the naming of Yersinia pestis. Yersin correctly described his bacillus as Gram-negative, while Kitasato insisted his was Gram-positive. Yersin also demonstrated for the first time that the same bacillus was present in rodents as well as in humans, underlining possible means of transmission. This was communicated to the French Academy of Sciences in a classic paper titled 'La peste bubonique à Hong-Kong'. Beyond the laboratory, he applied his knowledge in French Indochina, founding the Nha Trang Pasteur Institute, introducing rubber and quinine cultivation, and serving as the first headmaster of Hanoi Medical University. His legacy endures in Vietnam, where he is affectionately remembered as Ông Năm. The article notes that his anti-plague serum trials in Canton, Amoy, and Bombay yielded disappointing results, reflecting the challenges of early serum therapy.

Did You Know?

• Yersin's father died of a cerebral hemorrhage shortly before Alexandre's birth.
• Yersin obtained specimens of plague victims in Hong Kong by bribing English sailors responsible for disposing of bodies.
• Yersin correctly described the plague bacillus as Gram-negative, while Kitasato insisted his organism was Gram-positive.
• Yersin acclimatized the quinine tree (Cinchona ledgeriana) at Hon Ba in 1915, enabling Indochina to meet its quinine needs during World War II.
• In Vietnam, Yersin was affectionately called Ông Năm (Mr Nam/Five) due to his rank as a Colonel in the French army, with five horizontal lines in his insignia.