Robert Koch and the invention of the carrier state: tropical medicine, veterinary infections and epidemiology around 1900

This paper reassesses Robert Koch's work on tropical infections of humans and cattle as being inspired by an underlying interest in epidemiology. Such an interest was developed from the early 1890s when it became clear that an exclusive focus on pathogens was insufficient as an approach to explain the genesis and dynamics of epidemics. Koch, who had failed to do so before, now highlighted differences between infection and disease and described the role of various sub-clinical states of disease in the propagation and--consequently--in the control of epidemics. Studying pathologies of men and cattle in tropical countries eventually facilitated the application of such measures in Europe through the screening of healthy carriers of typhoid, which was carried out in 1902. The concept of the carrier state can be understood as a spin-off from tropical medicine into the study and control of infectious disease in Europe. With it travelled assumptions that were typical for colonial and veterinary medicine where the health of indigenous individuals or cattle would be a secondary objective compared to the control of diseases in populations.     

Koch is dead

Although the foundation of Koch's postulates, that "if an agent is the cause of disease in one individual it should be capable of causing disease in a second individual," is basically sound, the ritual that has evolved into present day experimental studies has obscured almost completely what occurs in natural processes outside the laboratory. Through a series of examples, it is emphasized that just bringing the host and the parasite together is not enough, but that the circumstances under which this is done is equally important. These circumstances include: the prior history of the host; the host's behavioral patterns, environmental conditioning, and disease history; the circumstances of exposure; and the environmental factors related to the host and the parasite. Of equal importance is the individual variation (genetic, physiologic, immunologic, etc.) of the host and the individual variation (strains, immunogenicity, pathogenicity, virulence, etc.) of the parasite. Because the rigor of the present day "scientific method" demands clearcut and reproducible results and investigations require predictable performance of the parasite in an evenly maintained host that is in a highly constrained environment, we should not wonder why we cannot produce the events of nature. If we are going to understand diseases of wildlife, we must consider the genetic heterogenicity of the host and parasite population, and recognize the complexity of the environment in which both exist. Koch's postulates, in the narrow sense, will help us to identify parasitisms but will not provide us with an understanding of information about diseases in wildlife; the real significance of these parasitisms to the health of the individual and to the size of the population.(ABSTRACT TRUNCATED AT 250 WORDS)     

UeberSpiraea decumbens Koch

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Money and microbes: Robert Koch, tuberculin and the Foundation of the Institute for Infectious Diseases in Berlin in 1891

Starting from an assessment of how far Robert Koch's bacteriology had developed in the late 1880s this paper attempts to analyse different aspects of the process that led to the foundation of the Berlin Institute for Infectious Diseases in 1891. With the development of his supposed cure against tuberculosis, tuberculin, Koch attempted to give his research a new direction, earn a fortune with the profits and become more independent of Prussian government officials who, up to that point, had had a major influence on his career. In the period following the presentation of the cure in autumn 1890, however, it became clear that tuberculin's value in treatment was at most dubious. Thus, the failure of tuberculin meant that Koch had to drop his own plans and accommodate those of the Prussian Ministry of Culture. As a result he assumed directorship of the newly founded Institute for Infectious Diseases in Berlin. Even though this was definitely a prestigious position it reaffirmed Koch's dependency on Prussian government officials and was by no means the kind of institution he had aimed for at the outset.     

UeberMelica picta C. Koch

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Pasteur, Koch and American bacteriology

This study traces American awareness of the work of Louis Pasteur and Robert Koch from the 1860s to the 1890s. In the years before the Civil War, American interest in germ theories had appeared at times of epidemics and persisted to a limited extent among physician-microscopists. Discussions of Pasteur's work occurred primarily in the context of spontaneous generation and antisepsis. Few Americans imitated his work on immunology or studied with Pasteur, but his work on immunity influenced their faith in the potential of bacteriology as a solution to problems of infectious disease. Koch's discoveries of the bacterial agents of tuberculosis and cholera stimulated American medical and public health interest in bacteriology in a more practical way. Americans learned Koch's methods by taking his courses and imported them directly into their own laboratories. A context of enthusiasm for science, educational reform, and problems of infectious disease associated with urbanization and changes in agriculture aided the growth of bacteriology in the American context.