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Microbiology Ch. 14

Microbe-Human Interactions

Symbiosis living together have these relationships with countless microorganisms
Types of symbiosis Mutualism commensalism parasitism
Mutualism both benefits
Commensalism benefits one and neither benefits nor harms the other
Parasitism benefits one and the other is harmed
Normal (resident) flora/indigenous flora microbes that engage in mutual or commensal associations ration of cells: 10:1
Infection a condition in which pathogenic microbes penetrate host defenses, enter tissues, and multiply
Infectious disease an infection that causes damage or disruption to tissues and organs
Normal flora/indigenous microbiota organisms that colonize the body's surfaces without normally causing disease
Normal flora is... essential to the health of humans
Flora create... an environment that may prevent infections and can enhance host defenses
What may alter flora? antibiotics, dietary changes, and disease
Probiotics introducing known microbes back into the body
Opportunistic pathogens normal flora that cause disease under certain circumstances
Conditions that provide opportunities for opportunistic pathogens? -introduction of normal flora into unusual site in body -immune suppression -changes in the normal flora ----changes in relative abundance may allow opportunity for a member to thrive and cause disease
Reservoirs of infection sites where pathogens are maintained as a source of infection
3 types of reservoirs Animal reservoirs Human carriers Nonliving reservior
Zoonoses diseases naturally spread from animal host to humans (MAJORITY OF HUMAN INFECTIONS)
Acquire zoonoses through various routes... -direct contact with animal or its waste -eating animals -vectors
Vector a live animal that transmits an infectious agent from one host to another
Majority of vectors are? anthropods: fleas, mosquitos, flies, and ticks
Biological vectors actively participate in a pathogen's LIFE CYCLE
Mechanical vectors not necessary to the life cycle of an infectious agent and MERELY TRANSPORTS it without being infected
Human carriers infected individuals who are asymptomatic but infective to others -some individuals eventually develop illness while others never get sick
Nonliving reserviors soil, water, fomites, and food can be reservoirs of infection
Fomites inademiate object -cell phone
Pathogenicity ability of a microorganism to cause disease
Virulence -look @ structure & chemistry help to be pathogenic -factors contribute to pathogenicity: Adhesion factors biolfims extracellular enzymes toxins antiphagocytic factors
Infectious dose -minimum number of microbes required for infection to proceed -microbes with smaller IDs have greater virulence
Infectious diseases five stages -incubation period -prodromal period -illness -decline -convalence
Incubation period no sign/symptom-pathogen colonized
Prodromal period feel under the weather, not typical sign
illness really feel it, signs/symptoms
decline get better
Localized Infection microbes enter the body and remains confined to a specific tissue
Systematic infection infection spreads to several sites and tissue fluids usually in the bloodstream
Focal infection when infectious agent breaks loose from a local infection and is carried to other tissues
Mixed infection several microbes grow simultaneously at the infection site-POLYMICROBIAL
Primary infection initial infection
Secondary infection another infection by a different microbe
Acute infection comes on rapidly, with sever but short-lived effects
Chronic infections progress and persist over a long period of time
epidemiology the study of where and when diseases occur, and how they are transmitted
Mortality rate total number of deaths in a population due to a certain disease
Morbidity rate number of people afflicted with a certain disease
Prevalence number of total cases of a disease in a given area during a given period of time
Sporadic when occasional cases are reported at irregular intervals
Endemic disease that exhibits a relatively steady frequency over a long period of time in a particular geographic locale
Epidemic when prevalence of a disease is increasing beyond what is expected
Pandemic epidemic across countries and continents
Created by: KatelynnJoy