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ASM 345 Notes

ASM 345 Notes - Infections in Pre-Antibiotic Era Infections...

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Infections in Pre-Antibiotic Era Infections were the major causes of death and disabilities Antisepsis- people were being cleaner and worried about sanitation. Parasitism- one organism benefits while the other organism is harmed Amount of harm can vary Mosquitoes bite causes minor irritation Some parasites steal nutrients Some major damage can result in the death of the host Encompass everything from prokaryotes up to the diversity of metazoans One of the most common lifestyles in existence with an estimate of 1/3 of life being parasitic. Only 35 animal groups do not have representative parasitic members. Epidemiology- The study of the distribution and determinants of health related states or events in specified populations and the application of this study to control of health problems. Focus not on the individual Focus on diseases Doesn’t consider species, organisms or genes Concerned with factors that influence the distribution of illness and injuries. Worried about controlling the disease rather than understanding Assumptions of Epidemiology Disease doesn’t occur at random, study disease distribution in sub groups Koch’s postulate- a method for establishing that specific microbes cause specific diseases. Types of Hosts Reservoir Host Any animal that carries a parasite that can cause infections in humans Related to the medical perspective of parasitology Vector Any organism that transmits infections to humans, like mosquitoes Parasite Vs. Predator Predation results in the death of one of the organism. Parasites usually try to keep host alive. Predator is larger than the prey. Predator preys on many individuals in a lifetime. Parasites usually spend entire life in one or two hosts.
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Virulence and Disease Virulence- Severity of a reaction to a disease. The conventional wisdom is that pathogens should lower their virulence If you are too harmful, you are going to kill off your host and not fully benefit. A reproducing host provides more hosts for future endeavors. If a parasite is more virulent, then it must have come from another host where the reaction to the parasite was more benign. A fully evolved parasite would not harm the host because it intends to survive. Pathogenesis is the evidence of recent associations between parasites and their hosts. Virulence is an indication that not enough time has elapsed for a benign association to evolve. (Not necessarily true) The mode of transmission is expected to influence the level of virulence in a host pathogen relationship. Horizontal- From human to human. Vertical- From mother to child (AIDS, Hepatitis B) Ability to build up resistance to pathogen Host Specificity Some parasites can move across hosts. If it can move to another host, why wouldn’t it? Some parasites are specialists and some are generalists.
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ASM 345 Notes - Infections in Pre-Antibiotic Era Infections...

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