Principles of Disease and Epidemiology

Topics: Infectious disease, Epidemiology, Infection, Bacteria, Disease / Pages: 8 (1896 words) / Published: Nov 26th, 2011
Chapter 14 – Principles of Disease and Epidemiology

Pathology Infection and Disease 1. Pathology is the scientific study of disease – concerned with cause (etiology) and manner in which disease develops (pathogenesis) - Also concerned with structural and functional changes brought about by disease and final effects on the body 2. Infection – invasion or colonization of the body by pathogenic microorganisms 3. Disease – when infection results in change in state of health
Normal Microbiota – 1. Free of microbes in utero, at birth gain lactobacilli in intestine from mothers vaginal canal, E. coli taken through food and inhabits intestine thru life 2. Ten times more bacterial cells than human cells in the body 3. Normal flora – normal microbiota 4. Transient microbiota – present for a while but disappear 5. Distribution of normal flora dependent on physical and chemical factors, defenses of the host and mechanical factors
Relationship between Normal Flora and Host 1. Microbial antagonism – aka competitive exclusion – normal microbiota ability to protect the host from overgrowth of harmful microorganisms 2. Normal microbiota and host live in symbiosis – one is dependent on the other 3. The three types of symbiosis – commensalism (one organism benefits, other unaffected), mutualism (both benefit) and parasitism (one harmed and one benefits) 4. Probiotics – live microbial cultures applied to or ingested that are intended to exert a beneficial effect
Opportunistic Microorganisms 1. E. coli – normally harmless but in other parts of the body – cause UTI, pulmonary infections, meningitis or abscesses. 2. AIDS – compromises immune system – increases susceptibility to opportunistic infection e.g. Pneumocystis pneumonia

The Etiology of Infectious Disease –
Koch’s Postulates – 1. Koch established that microorganisms cause specific disease 2. Isolated microorganisms from diseased animal, grew in pure

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