Target Health Blog

Alexandre Emile Jean Yersin MD (1863-1943)

June 10, 2019

History of Medicine

Alexandre Emile Jean Yersin (1863-1943), physician and bacteriologist
Photo credit: By Rvalette; edited by Jaybear - Own work, Public Domain,

The causative bacterium of plague was described and cultured by Alexandre Yersin in Hong Kong in 1894, after which transmission of bacteria from rodents by flea bites was discovered by Jean-Paul Simond in 1898. Effective treatment with antiserum was initiated in 1896, but this therapy was supplanted by sulphonamides in the 1930s and by streptomycin starting in 1947. India suffered an estimated 6 million deaths in 1900-1909, and Vietnam, during its war in 1965-1975, accounted for approximately 80% of the world's cases. Since then, African countries have dominated, with >90% of the world's cases in the 1990s and early 21st century. Serological diagnosis with fraction 1 antigen to detect anti-plague antibodies was developed in the 1950s. Vaccine development started in 1897 with killed whole bacterial cells, and this was followed by a live attenuated bacterial vaccine, leading to millions of persons receiving injections, but the benefits of these vaccines remain clouded by controversy. Plasmid-mediated virulence was established in 1981, and this was followed by specific DNA methods that have allowed detection of plague genes in skeletal specimens from European graves of the sixth to 17th centuries.

The modern history of plague began in 1894, when Alexandre Yersin isolated the causative bacterium in culture and identified it under the microscope. This event allowed laboratory confirmation for accurate diagnoses. There followed many advances in treatment and diagnosis, as well as scientific understanding of the disease.

Alexandre Emile Jean Yersin (22 September 1863 - 1 March 1943) was a Swiss and naturalized French physician and bacteriologist. He is remembered as the co-discoverer of the bacillus responsible for the bubonic plague or pest, which was later named in his honor (Yersinia pestis). Yersin also demonstrated for the first time that the same bacillus was present in the rodent as well as in the human disease, thus underlining the possible means of transmission. Yersin was born in 1863 in Aubonne, Canton of Vaud, Switzerland, to a family originally from France. From 1883-1884, Yersin studied medicine at Lausanne, Switzerland; and then at Marburg, Germany and Paris (1884-1886). In 1886, he entered Louis Pasteur's research laboratory at the Ecole Normale Sup?rieure, by invitation of Emile Roux, and participated in the development of the anti-rabies serum. In 1888 he received his doctorate with a dissertation titled Etude sur le Developpement du Tubercule Experimental and spent two months with Robert Koch in Germany. He joined the recently created Pasteur Institute in 1889 as Roux's collaborator and discovered with him the diphtheric toxin (produced by the Corynebacterium diphtheriae bacillus).

To practice medicine in France, Yersin applied for and obtained French nationality in 1888. Soon afterwards (1890), he left for French Indochina in Southeast Asia as a physician for the Messageries Maritimes company, on the Saigon-Manila line and then on the Saigon-Haiphong line. He participated in one of the Auguste Pavie missions. In 1894 Yersin was sent by request of the French government and the Pasteur Institute to Hong Kong, to investigate the Manchurian pneumonic plague epidemic. There, in a small hut (according to Plague by Wendy Orent) since he was denied access to English hospitals at his arrival, he made his greatest discovery: that of the pathogen which causes the disease. The plague bacillus develops better at lower temperatures, so Yersin's less well-equipped lab turned out to be an advantage, over other researchers who used incubators. Yersin was also able to demonstrate for the first time that the same bacillus was present in the rodent as well as in the human disease, thus underlining the possible means of transmission. This important discovery was communicated to the French Academy of Sciences in the same year, by his colleague Emile Duclaux, in a classic paper titled "La peste bubonique a Hong-Kong".

From 1895 to 1897, Yersin further pursued his studies on the bubonic plague. In 1895 he returned to the Institute Pasteur in Paris and with Emile Roux, Albert Calmette and Am?d?e Borrel, prepared the first anti-plague serum. In the same year, he returned to Indochina, where he installed a small laboratory at Nha Trang to manufacture the serum (in 1905 this laboratory became a branch of the Pasteur Institute). Yersin tried the serum received from Paris in Canton and Amoy, in 1896, and in Bombay, India, in 1897, with disappointing results. Having decided to stay in his country of adoption, he participated actively in the creation of the Medical School of Ha Noi in 1902, and was its first director, until 1904. Yersin tried his hand at agriculture and was a pioneer in the cultivation of rubber trees (Hevea brasiliensis) imported from Brazil into Indochina. For this purpose, he obtained in 1897 a concession from the government to establish an agricultural station at Suoi Dau. He opened a new station at Hon Ba in 1915, where he tried to acclimatize the quinine tree (Cinchona ledgeriana), which was imported from the Andes in South America by the Spaniards, and which produced the first known effective remedy for preventing and treating malaria (a disease which prevails in Southeast Asia to this day).

Alexandre Yersin is well remembered in Vietnam, where he was affectionately called Ong Nnm (Mr. Nam/Fifth) by the people. On 8 January 1902, Yersin was accredited to be the first Headmaster of Hanoi Medical University by the Governor-General of French Indochina, Paul Doumer. Following the country's independence, streets named in his honor kept their designation and his tomb in Suoi Dau was graced by a pagoda where rites are performed in his worship. His house in Nha Trang is now the Yersin Museum, and the epitaph on his tombstone describes him as a "Benefactor and humanist, venerated by the Vietnamese people". In Ha Noi, a French lycee has his name. A private university founded in 2004 in Da Lat was named "Yersin University" in his honor. In 1934 he was nominated honorary director of Pasteur Institute and a member of its Board of Administration. He died during World War II at his home in Nha Trang, in 1943.

Dr. Yersin was credited with finding the site for the town of Dalat (300 km northeast of Saigon) in 1893. Because of the high altitude and European-like climate, Dalat soon became an R&R spot for French officers. There was a high school named after him which was built in the 1920s, the Lycee Yersin, aka Grand Lycee (grade 6 to 12), the Petit Lycee (elementary to grade 5) and a university named for him which was built in the 2000s. While in Hong Kong, Yersin was helped in his research by an Italian priest of the PIME order, Bernardo Vigano (1837-1901), who provided cadavers and assisted him with his quest to find a remedy for the plague.

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