Historia De La Tuberculosis

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The Etiology of Tuberculosis: A Tribute to Robert Koch,on the Occasion of the Centenary of His Discovery of the Tubercle Bacillus*
Dieter H. M. Griischel Departments of Pathology and Internal Medicine University of Virginia School of Medicine Charlottesville, Virginia 22908 Announcement of the Discovery On 24 March 1882 a young Regierungsrath (“government councillor“ - a civilservice rank) of the Imperial Health Office, Robert Koch, presented a paper on the etiology of tuberculosis to the Physiological Society of Berlin in the library of the university’s physiology institute. Basing his studies on investigations by Villemin, Cohnheim, and others who had shown the transmissibility of tuberculosis, Koch had started laboratory experiments with tuberculosis in the summerof 1881 and inoculated the first guinea pigs on 18 August 1881 (10). Within about 8 months he was able to prove the infectious nature of the tubercle bacillus by studying the histology of human and animal tuberculosis. He infected guinea pigs and other animals, developed a method to stain the bacilli in histological specimens and heat-fixed smears of biopsy materials and sputum, grew the bacilluson solid media, and described the airborne transmission. Thus, he ful* Presented at the 21st Annual Swineford Conference at the University of Virginia School of Medicine, Charlottesville, on 16 April 1982. 248

filled the postulates of his Gottingen teacher, Jakob Henle, who had stated in 1840 that in order to prove the infectious nature of a disease, a germ must be identified in the affectedorganism, the germ must be isolated and grown in pure culture, and the disease must be reproduced in experimental animals by these pure cultures with subsequent recovery of the same germ. These postulates are known today as Koch’s postulates Paul Ehrlich, a young medical assistant in 1882, described this memorable event: “Koch had discovered the tubercle bacillus. It was in a small room of thePhysiological Institute where Koch, using simple and clear words and offering numerous preparations and exhibits, demonstrated the etiology of tuberculosis with convincing vigor. Everyone who had attended the lecture was deeply stirred, and I must say that this evening has always been kept in my memory as my greatest scientific experience” (10). Why was this event so important that 100 years later westill remember it? Tuberculosis was a widespread disease in Europe, and in 1882 tuberculosis mortality amounted to more than 300 cases per 100,000 inhabitants in Prussia and other countries as well. More than one-third of infant deaths and one-half of deaths between 15 and 45 years of age were caused by this disease (11). Its nature was not clear; it was considered to be not

infectious, butrather hereditary or neoplastic. The work by Villemin and others on the infectious nature of tuberculosis did not succeed in defeating the earlier theories. Only Koch’s convincing experiments and observations “brought the full evidence for the parasitic nature of a human infectious disease, and for the most important one of all.” They even convinced Virchow, who earlier had expressed contempt for the‘Ijuvenile work” of the “youngsters” at the Imperial Health Office (7). Koch himself stated, “My investigations were performed in the interest of health care to which, as I hope, its greatest benefit will accrue.” In addition to describing human tuberculosis, he declared pearl disease of cattle to be bovine tuberculosis. Effects of the Announcement Koch’s presentation had one interesting immediatereaction. Paul Ehrlich (mentioned above) was so impressed by Koch’s demonstration

Robert Koch in 1883 (photo courtesy of W. Brehmer, Robert-Koch-Institut des Bundesgesundheitsamtes Ber. lzn)
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that he returned to the laboratory right after the lecture and experimented with another staining method (10). Whereas Koch had used an alkaline methylene blue solution which required 20 to...