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Priming of immune system organisms of the normal

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Priming of Immune System Organisms of the normal flora play an important role in the development of immunologic competence. Animals delivered and raised under completely aseptic conditions ("sterile" or gnotobiotic animals) have a poorly developed reticuloendothelial system, low serum levels of immunoglobulins, and none of the antibodies to normal floral antigens that often confer a degree of protection against pathogens. There is evidence of immunologic differences between children who are raised under usual conditions and those whose exposure to diverse flora is minimized. Some studies have found a higher incidence of asthma in the more isolated children. Promoting "Good" Flora
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The field of probiotics promotes colonization with "good" flora such as with lactobacilli in the intestinal tract. Elie Metchnikoff originally suggested that the longevity of Bulgarian peasants was attributable to their consumption of large amounts of yogurt; the live lactobacilli in the yogurt presumably replaced the colonic flora to the general benefit of their health. This notion persists today in the alleged benefit of natural (unpasteurized) yogurt, which contains live lactobacilli. Although we now know that lactobacillary replacement of the flora of the adult colon does not take place so easily, there have been some successes with capsules containing lyophilized bacteria. In some studies, administration of preparations containing a particular strain of Lactobacillus ( L rhamnosus strain GG , LGG) has reduced the duration of rotavirus diarrhea in children and prevented relapses of antibiotic-associated diarrhea caused by C difficile . Infectious Disease Epidemiology Pathogenesis Immunity Clinical Aspects of Infectious Disease Manifestations Diagnosis Treatment Prevention Summary Of the thousands of species of viruses, bacteria, fungi, and parasites, only a tiny portion is involved in disease of any kind. These are called pathogens . There are plant pathogens, animal pathogens, and fish pathogens, as well as the subject of this book, human pathogens. Among pathogens, there are degrees of potency called virulence , which sometimes makes the dividing line between benign and virulent microorganisms difficult to draw. Other pathogens are virtually always associated with disease of varying severity. Yersinia pestis, the cause of plague, causes fulminant disease and death in 50% to 75% of persons who come in contact with it. It is highly virulent. Understanding the basis of these differences in virulence is a fundamental goal of this book. The better that students of medicine understand how a pathogen causes disease, the better they will be prepared to intervene and help their patients. For any pathogen the basic aspects of how it interacts with the host to produce disease can be expressed in terms of its epidemiology, pathogenesis, and immunity. Usually our knowledge of one or more of these topics is incomplete. It is the task of the physician to relate these topics to the clinical aspects of disease and be prepared for new developments which clarify, or in some cases, alter them. We do not know
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Priming of Immune System Organisms of the normal flora play...

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