A Perspective of Infection and Infectious Disease

A PERSPECTIVE OF INFECTION AND INFECTIOUS DISEASE PHILLIP PETERSEN* Introduction Respiratory diseases of bacterial aetiology are common in all populations . Such infections involving drug-resistant organisms often follow therapy with antibacterial drugs, which all too often have been prescribed as a result of bacteriological misinformation. Diarrheal diseases, frequently of bacterial aetiology and synergistic with malnutrition, are usually the largest factors in morbidity and mortality in children- in underdeveloped countries, and even among certain population groups in so-called developed countries. Despite this, microbiology was virtually neglected for many years, with the belief that infectious disease was virtually a thing of the past. "In reality, many patients die because their ability to fight off perfectly normal organisms is so lowered that they can't cope with them; they fall apart as a result of infection" [I]. This belief was largely founded on a conviction that antibiotic treatment could eliminate disease, a conviction that is wrong on two counts. Firstly, "I think we are finally beginning to appreciate that hospitals are at the very apex of a selective pressure pyramid for highly antibioticresistant organisms. We have been selecting very carefully microbial particles which are not at all amenable to treatment" [I]. Secondly, "We are apt to lose sight of the fact that treatment alone is inadequate to control the spread of infection. Almost without exception, infection has spread to susceptible contacts prior to successful treatment of the index case" [2]. There are many today who believe that we have gone about as far as we can in the field of infectious disease. I believe such pessimism is as unfounded as was the earlier optimism and that both owe their unsoundness to the same root cause—a perspective of infectious disease which is so incomplete in essential details as to be completely misleading. ?Microbiology Department, Queensland Medical Laboratory, 86 Astor Terrace, Brisbane , Queensland, Australia 4000.© 1980 by The University of Chicago. 0031-5982/80/2302-01 19$01 .00 Perspectives in Biology and Medicine ¦ Winter 1980 | 255 This perspective is basically that of Koch. The central tenets of this perspective can be stated: (1) infectious disease is due to an attack on a host by a parasite; (2) a specific microbial species causes a specific disease; (3) the causal nature of any microbial species in any disease must be proven in accord with Koch's postulates; (4) infectious disease may be treated by killing the parasite. The Importance ofPerspectives "Facts do not organize themselves into concepts and theories by being looked at; indeed, except within the framework of concepts and theories, there are no scientific facts but only chaos. There is an inescapable a priori element in all scientific work. Questions must be asked before answers can be given. The questions are all expressions of our interest in the world, they are at bottom valuations" [3]. As an illustration of this, consider the discoveries, consequent on the invention of the microscope, that bits of cork are made up of tiny compartments , that pieces of meat are made of tiny elongated units, that leaves of trees are made of small rectangular units—all interesting but not very useful facts until the suggestion was made that perhaps all living things are made of these tiny units. Again, to step outside the field of biology for a moment, it is unlikely that astronomers before Copernicus sat around in their coffee breaks discussing the remarkable fact that the sun moves round the earth, but this perspective of the universe so blinded them that they were apparently completely unable to see the numerous celestial objects discovered in a very few years after the Copernican view became accepted. This occurrence is also an illustration of the truth of the observation that "generally speaking, we can observe that scientists in any particular institutional setting move as a flock, reserving their controversies and particular originalities for matters that do not call into question the fundamental system of biases they share" [3]. Historical Overview Koch's perspective of disease, the so-called germ theory of disease, traces back some 6 millennia to the Egyptian perspective of disease as occurring when a parasite finds an environment suitable to life within the body of...