MCB Exam 3 Lecture 20 Ch 14 Objectives Define pathology etiology infection and disease Pathology the scientific study of disease etiology The study of the cause of a disease infection Growing and multiplying of pathogens in the host disease An abnormal state in which the body is not functioning normally when an infection results in change from a state of health Define normal transient microbiota and opportunistic infections Normal microbiota the microorganisms that establish more or less permanent residence colonize but do not produce disease under normal conditions transient microbiota may be present for days weeks or months then disappear Opportunistic infections don t normal cause disease in their normal habitat in a healthy person but do so in different environments ex broken skin mucous membrane immunocompromised AIDS pneumocytis pneumonia etc Compare and contrast commensalism mutualism and parasitism Symbiosis the relationship between the normal microbiota and the host the relationship between two organisms in which at least one organism is dependent on the other Commensalism one of the organisms benefits the other is unaffected Eyes ears genitals mutualism a type of symbiosis that benefits both organisms The large intestine provides nutrients for the bacteria that synthesize vitamin K and some B vitamins parasitism one organism benefits by deriving nutrients at the expense of the other Many disease causing parasites Understand Koch s postulates and the exceptions Koch s postulates are used to prove the cause of an infectious disease Specific disease is cause by a specific organism 1 The same pathogen must be present in every case of the disease 2 The pathogen must be isolated from the diseases host and grown in pure culture 3 The pathogen from the pure culture must cause the disease when it is inoculated into a healthy susceptible lab animal 4 The pathogen must be isolated from the inoculated animal and must be shown to be the original animal exceptions koch s postulates are useful for determining the causative agent of most bacterial diseases there are some exceptions some microbes have unique culture requirements ex treponema pallidum syphilis virulent strains have never been cultured in artificial media Discovery of microbes that cant grow on artificial media has necessitated some modifications of Koch s postulates and the use of alternative methods of culturing and detecting certain microbes ex inoculating diseases into animals instead of on artificial media then inoculate egg yolk and then compare bacteria in animal and eggs another exception to koch s postulates is that some pathogens can cause several disease conditions Mycobacterium tuberculosis for example is implicated in diseases of the lungs skins bones and internal organs Some pathogens need cofactors Development of some diseases takes years another ethical exception is that some agents that cause disease in humans have no other known host ex HIV This poses the ethical question of whether or not humans can be intentionally inoculated with infectious agents Understand predisposing factors for disease A predisposing factor makes the body more susceptible to a disease and may alter the course of the disease gender females have a higher incidence of UTIs than males males have higher rates of meningitis and pneumonia genetic background climate and weather inadequate nutrition age environment habits lifestyle occupation preexisting illness chemotherapy and emotional disturbances Define reservoir of infection A source for the disease to perpetuate itself where there must e a continual source of the disease organisms This source can be either a living organism or an inanimate object that provides a pathogen with adequate conditions for survival and multiplication and an opportunity for transmission These reservoirs may be human animal or nonliving Continual sources of infection Human AIDS gonorrhea Carriers may have inapparent infections or latent diseases Animal Rabies Lyme disease Some zoonoses may be transmitted to humans Nonliving Botulism tetanus Soil Explain three methods of disease transmission Contact transmission Direct Requires close association between infected and susceptible host touching kissing sexual intercourse Indirect fomites tissues towels bedding diapers drinking cups toys moneys etc Droplet Transmission via airborne droplets Vehicle transmission Vectors Transmission by an inanimate reservoir food water Arthropods especially fleas ticks and mosquitoes Mechanical Arthropod carries pathogen on feet eg flies transfer pathogens typhoid fever from feces of infected to food Biological Pathogen reproduces in vector Lymes WNV Define epidemiology The science that studies when are where diseases occur and how they are transmitted in populations modern epidemiology began in the mid 1800s Know the contribution of John Snow Ignaz Semmelweis and Florence Nightingale john snow conducted a series of investigations related to outbreaks of cholera in london Found out it was from a single contaminated well Ignaz Semmelweis recorded number of births and maternal deaths in Vienna General Hospital Showed that hand washing decreased the incidence of puerperal fever Florence Nightingale recorded statistics on epidemic typhus in the english civilian and military populations She published a paper reporting that diseases poor food and unsanitary conditions were killing the soldiers This led to military reform Identify the function of the CDC Centers for disease control and prevention a branch of the US Public Health Service in ATL is a central source of epidemiological information Collects and analyzes epidemiological information in the United States Publishes Morbidity and Mortality Weekly Report MMWR www cdc gov Define the terms morbidity mortality and notifiable disease Morbidity Incidence of a specific notifiable disease Mortality Deaths from notifiable diseases Morbidity rate Number of people affected in relation to the total population in a given time period time Mortality rate Number of deaths from a disease in relation to the population in a given Notifiable infectious diseases are diseases that physicians are required by law to report cases to the US public health service Terminology Normal microbiota functions prevents overgrowth of harmful microorganisms Summary This phenomenon is called microbial antagonism or competitive exclusion Microbial antagonism involves competition among microbes microbiota competes
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