sept 20 - What is TB? o Exposure o Infection o Disease o...

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What is TB? o Exposure o Infection o Disease o Disease caused by M. Tuberculosis o Primarily involving the lungs o Spread by airborne transmission o Coughing, sneezing, yelling – any aspiration from lungs o Aerosolized bacilli ho Aerosolized M.tb. can be inhaled by anyone breathing the same air o Risk of infection depends on closeness and duration of contact infectiousness of source volume of air space, ventilation o 20-50% of close household contacts Multiplications of Bacilli o Multiplication in alveolar space o Establishment of TB infection dependent on: § Number of organisms § Host factors Dissemination of Disease o Disease of lungs Immune reaction to infection o Specialized immune cells (lymphocytes and macrophages) invade the sites of infection, surround and engulf the bacteria The TB skin test (PPD) detects this immune response to TB
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Progression to disease o If bacteria escape body’s defenses, TB disease develops o A 10% lifetime risk of developing active TB disease o Risk highest within 1 st 2 years o 905 of people infected will not develop disease Sick patients symptoms TB caused by Mycobacterium tuberculosis
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sept 20 - What is TB? o Exposure o Infection o Disease o...

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