Was Shibasaburo Kitasato the Co-Discoverer of the Plague Bacillus?

WAS SHIBASABURO KITASATO THE CO-DISCOVERER OF THE PLA G UE BA CILL USf NORMAN HOWARD-JONES* The conventional story of the discovery of Pasteurella pestis (as it is now named) is that Alexandre Yersin and Shibasaburo Kitasato, respectively disciples of Pasteur and Koch, independently and almost simultaneously incriminated this organism as the pathogenic agent of plague during an outbreak of the disease in Hong Kong in 1894. Behind this oversimplification lies a veritable enigma, of which the present paper is presented as the probable solution. Among the standard historical works repeating the conventional story is William Bulloch's History of Bacteriology (1938)—usually regarded , with justice, as a model of careful scholarship by a scientist specializing in the subject matter. Bulloch states that "in 1894 Kitasato and Yersin discovered the plague bacillus" (p. 237), and in a biographical note he affirmed categorically that Kitasato "discovered plague bacillus in 1894" (p. 375). Isidor Fischer, in his Biographisches Lexicon . . . (1932), attributed to Kitasato the discovery of the plague bacillus "several days before Yersin" (p. 765). Fielding H. Garrison, in the fourth edition of his Introduction to the History of Medicine (1929), credited Kitasato and Yersin jointly with the discovery (p. 582), as did Arturo Castiglione in his A History of Medicine (English translation, 1941, p. 811) and Charles-Edward A. Winslow in The Conquest of Epidemic Disease (1943, p. 357). Richard Shryock, in the second edition of The Development of Modern Medicine (1947), goes much further, without even mentioning Yersin's name in connection with plague, in hailing Kitasato as having "added to his fame in 1894, when he discovered the cause of bubonic plague during an epidemic * Visiting scientist, History of Medicine Division, National Library of Medicine, National Institutes of Health, Public Health Service, Department of Health, Education, and Welfare. Reprint requests from outside North and South America should be addressed to the author at 28 Chemin Colladon, 1211 Geneva 19, Switzerland. 292 I Norman Howard-Jones · Co-Discoverer of the Plague Bacillus? at Hong Kong, and thus exposed one of the historic enemies of man" (p. 286). Standard works on tropical medicine and on bac teriology tell much the same story.1 For example, in the sixteenth edition of Manson's Tropical Diseases (1966) credit is allotted equally to Kitasato and Yersin (p. 223), as is the case with the fifth edition of Topley and Wilson's Principles of Bacteriology and Immunity (1964, p. 1958). Robert Pollitzer, in his monograph, Plague, published by the World Health Organization in 1954, mentions Yersin as the discoverer of the plague bacillus (p. 74), and, citing a preliminary communication by Kitasato of 1894,2 says that "Kitasato and many other observers" thought that it was a capsulated organism. Pollitzer nowhere suggests that Kitasato's bacillus may have been different from that of Yersin. The fourteenth edition of Zinsser's Microbiology (1968) shows more caution, for it says that the plague bacillus "was seen in smears by Kitasato but isolated and identified by the Swiss bacteriologist Yersin " (p. 689). In this context, the distinction between "seen" and "identified" is not easy to discern. Even more caution was shown by Hubert A. Lechevalier and Morris Solotorovsky in their Three Centuries of Microbiology (1965). Discussing Yersin's undoubted discovery of the plague bacillus, they add: "During this time Kitasato also thought that he had discovered the organism responsible for plague; however in his first publication that appeared in Lancet he admitted that he could not determine whether the organism that he was working with was Gram-positive or negative. His description was not as good as Yersin's, and the purity of his cultures was in question" (p. 156). There is no hint of why the purity of Kitasato's cultures was in question, nor of who questioned it. In A History of Tropical Medicine (1939), Sir H. Harold Scott, a onetime government bacteriologist in Hong Kong, stated flatly that Kitasato "probably mistook some contaminant for the causative organism" (p. 730), but his statement was not supported by any explanation or reference to the literature. Moreover, Scott's work contains some extraordinary errors, not the least of which is to describe Yersin—a Swiss who became...