TRAVELS OF ALEXANDRE YERSIN: LETTERS OF A PASTORIAN IN INDOCHINA, 1890-1894 JACK E. MOSELEY* Medicine today, in America and elsewhere, owes much to the microbe hunters of nineteenth-century Europe who established and propagated the germ theory. One of the lesser known but exceedingly versatile of these microbe hunters was the Swiss-born doctor Alexandre Yersin, codiscoverer of the diphtheria exotoxin and discoverer of the plague bacillus, whose genus is named in his honor [I]. This gifted phy- sician—the protégé of Louis Pasteur and Emile Roux—left a legacy of nearly 1,000 letters, many over 10 pages long, which he had written to his mother. Detailing over 40 years of his life and work, the collection was discovered in Switzerland in 1970 by the doctor's descendants and donated to H. H. Mollaret, plague specialist of the Pasteur Institute of Paris. Dr. Mollaret made the letters available for translation by myself and publication in the United States. The following selections concern primarily the earlier biographical aspects of the correspondence, par- ticularly those highlighting Yersin's remarkable experience as a ship's doctor, explorer, and cartographer in the Far East. The following letters have not previously been published. Alexandre Yersin (see fig. 1) was a small, quiet physician whose slen- der stature rarely measured above the shoulders of many of his nineteenth-century European contemporaries. It is, perhaps, under- standable that some of his professional colleagues tried to dissuade him H. H. Mollaret and Jacqueline Brossollet of the Pasteur Institute of Paris, Albert Co- blentz of the Faculty of Medicine of the University of Paris, Robert P. Hudson of the Department of the History of Medicine of the University of Kansas, Caroline Hannaway of the Institute of the History of Medicine of the Johns Hopkins University, and Thomas K. Akers of the University of North Dakota served as historical advisers for this manuscript. Additional assistance in its preparation was provided by the Logan Clendening Traveling Fellowship in the History of Medicine and the following faculty and staff of the University of North Dakota: Lorraine Etti, Vonda Somerville, Colleen Kenefick, Lowell Gallagher, Claudine Moseley, and Brenda Perry. The manuscript is dedicated to Bessie F. Presley, 1905-1980. »Address: 2843 St. Paul Street, Baltimore, Maryland 21218. © 1981 by The University of Chicago. 0031-5982/81/2404-0249$01.00 Perspectives in Biology and Medicine · Summer 1981 | 607 from leaving a flourishing medical career in Paris in 1890 to pursue the rigors of exploration in colonial Indochina [2]. The 27-year-old physi- cian had not once been to sea or traveled farther than to a few countries in Europe. The sketches of Paris he frequently sent to his mother in Switzerland were the only indication of the cartography skills he might possess for mapping the uncharted lands of which he dreamed [3]. Yersin was born in the French-speaking Canton of Vaud in Switzer- land, on September 22, 1863. He came to Paris in 1885 to study medicine at the renowned Faculty of Medicine of the University of Paris. As a medical student, his decision to specialize in microbiology came to the attention of Louis Pasteur and Emile Roux, who became his in- Fig. 1.—Alexandre Yersin, circa 1894, wearing the medal of "la Légion d'honneur" awarded by the French government for his discovery of die plague bacillus in Hong Kong in June 1894. 608 J Jack E. Moseley ¦ Travels ofAlexandre Yersin structors and mentors [3]. Yersin's doctoral thesis of 1888 described his work in experimentally induced septicemic tuberculosis, known later as "la tuberculose expérimentale, type Yersin" [3, p. 197]. Also in 1888, Roux and Yersin worked closely on a series of filtration experiments which led to history's first isolation of a bacterial toxin, the exotoxin of Corynebacterium diphtheria [3, p. 197]. In 4 of the 6 years that followed this discovery, Yersin traveled widely in Indochina as a colonial physician, explorer, and cartographer. He documented his journeys, and the days leading up to them in France, in biweekly letters to his mother in Morgès, Switzerland. His first-person accounts, as reproduced in the following passages, contribute to his biography, in particular to that 4-year period of transition and travel, 1890-1894, which prefigured his future medical career in Indochina and set the stage for bis next major step in the field of microbiology, the discovery of the bacillus of the plague in Hong Kong in 1894. Early in Yersin's career at the Pasteur Institute, Emile Roux was Yer- sin's closest friend and his steadfast advocate: Throughout 1889, the year after Yersin's graduation from the Faculty of Medicine, the two men continued their work on diphtheria and, at Louis Pasteur's request, taught the first microbiology course at the institute [3, pp. 199-200]. Students and physicians from the French colonies and the world over came to Paris to study at the new Pasteur Institute and must have enticed Yersin with descriptions of their countries. It was difficult for Roux to conceive of the 27-year-old Yersin's growing desire to travel. Yersin spent his free days on the Normandy coast, contemplating the steam- ships bound for foreign ports [4]. The fragrance of an imagined life at sea followed him back to Paris: "I miss the sea. In the stillness of the night, I often think that I can hear it surging. I think I'm in love with it" (letter from Paris, September 15, 1889). As the prospect of a landlocked future loomed larger, Yersin, over Roux's objections, asked Pasteur for a 1-year leave of absence and per- mission to join the French merchant marine company, les Messageries Maritimes, whose extensive fleet of steam vessels transported cargo and passengers to France's colonies and to foreign countries throughout the world [4]. Pasteur approved and penned a letter of recommendation for him on March 5, 1890 [4, p. 18]. A new chapter in his life was about to begin. The motive for Yersin's momentous decision seems to have been tied to a deeply felt belief that his role in life would somehow be established in travels far from Europe. Clearly, he could have remained at the Pasteur Institute and collaborated with Roux on other experi- ments while enjoying the renown that had accompanied their discovery of the diphtheria exotoxin. As he tried tojustify in a letter a year later to his mother, his reasons for leaving the institute dated back to his child- hood: "You must remember that it has always been my innermost dream Perspectives in Biology and Medicine · Summer 1981 | 609 to follow in the steps of Livingstone" (letter from Saigon, August 28, 1891). So, with Pasteur's recommendation letter preceding him in 1890, Yer- sin went to the Paris offices of the Messageries Maritimes to request a position as ship's doctor: "On Thursday, I went with cousin Demole to see the administrator of the Messageries Maritimes. The certification from Mr. Pasteur had made an excellent impression. ...The entire company will be at my service if I wish to do research on the diseases of foreign countries. ...Mr. Metchnikoff is delighted. Mr. Roux continues to make his same grimace" (letter from Paris, March 9, 1890). Yersin continued his work at the Pasteur Institute during the next several months while waiting for his assignment orders from the Mes- sageries Maritimes. After his orders arrived in September, a note of insecurity appeared in his final letters to his mother before he boarded ship: "I received a dispatch telling me to arrive in Marseilles on Wednes- day in order to embark on Sunday for the Messageries Maritimes' out- posts in Indochina. ... I do not know in the slightest what I shall be doing over there" (letter from Paris, September 14, 1890). And, "It's a little difficult this last day before isolating myself so distantly from all of those dearest to me. Happily, distances do not exist for thoughts and affection" (letter from Marseilles, September 20, 1890). The next day, Yersin boarded the merchant marine steamer, Oxus, and embarked on a 3-week voyage to Saigon: We have been at sea for three days! It is not too disagreeable. I find that Mr. Roux exaggerated in telling me of the terrible boredom that I would experience on board ship. [Letter from the Mediterranean Sea, September 24, 1890] I slept on the bridge last night because the cabins were unbearably hot. Near one o'clock in the morning, we put down anchor at Aden and stopped quite a way from the shore. Soon, we saw some vague, torch-lit masses pulling away from the shore. A sort of rhythmic chant of several repeating notes arose from these rafts as they approached die Oxus. They were carrying the coal men coming to fill the fuel holds of the Oxus. Nothing can describe this remarkably strange scene. It made me feel so far away from Europe already. [Letter from the Indian Ocean, October 6, 1890] When the Oxus reached Saigon on October 15, Yersin described his first hours in the new land to his mother and related his anticipated new assignment on the freight steamer Volga which shuttled goods and pas- sengers across the south China sea between Saigon and Manila: Our ship's pier was situated just in front of the offices of the Messageries. Mr. Rolland, the principal agent, came aboard and told me that I was designated next for the Volga, which makes the run from Saigon to Manila. The next departure won't be until October 22, so I have two or three days in which to acclimate myself a bit.