chapter 14

normal flora

community of normal microbes

mutualism

organism 1: benefits

organism 2: benefits

commensalism

organism 1: benefits

organism 2: neither benefits nor is harmed

amensalism

organism 1: is harmed

organism 2: neither benefits nor is harmed

parasitism

organism 1: benefits

organism 2: is harmed

symbiosis

organisms living together

resident microbiota

• apart of the microbiome of humans

• usually commensal

transient microbiota

• apart of the microbiome of humans

• don’t live with us for long

reservoirs

sites where pathogens are maintained as a source of infection

zoonoses

diseases that are naturally spread from their usual animal hosts to humans

direct contact with animals, eating animals, bloodsucking arthropods

common transmission routes for zoonoses

human carriers

infected individuals who are asymptomatic but infective to others

soil, water, and food

examples of nonliving reservoirs

contamination

the mere presence of microbes in or on the body

infection

results when the organism has evaded the body’s external defenses, multiplied, and become established in the body

skin, mucous, placenta, parenteral route

4 portals of entry for infection

Attachment proteins

Viruses use ________ ________ for adhesion

Adhesions

Bacteria use _______ for adhesion

Etiology

Cause of infection

Symptoms

Subjective characteristics of disease felt only by the patient

Signs

Objective manifestations of disease that can be observed or measured

Syndrome

Group of symptoms and signs that characterize a disease or abnormal condition

Asymptomatic/ subclinical

Infections that symptoms but there are signs of infection

Pathogenicity

Ability of a microorganism to cause disease

Virulence

Degree of pathogenicity

incubation period, prodromal period, illness, decline, convalescence

5 stages following infection

incubation period

1st stage in disease where there are no signs or symptoms

prodromal period

2nd stage in disease where you experience vague general symptoms

illness

stage in disease where you experience the most severe signs and symptoms

decline

stage in disease where signs and symptoms decrease

convalescence

the final stage of recovery where strength and health return after illness; no signs or symptoms

direct contact

mode of contact transmission through physical contact (ex. handshaking, kissing, physical intercourse, bites)

indirect contact

mode of contact transmission through contaminated objects or surfaces (ex. drinking glasses, toothbrushes, toys, punctures)

droplet

mode of contact transmission from droplets from sneezing within 1 meter

airborne

mode of vehicle transmission air particles (ex. dust particles or droplets carried more than 1 meter)

waterborne

mode of vehicle transmission through contaminated water sources (ex. streams, swimming pools)

foodborne

mode of vehicle transmission through contaminated food

mechanical

mode of vector transmission by insects or animals that carry pathogens mechanically on their bodies or in their saliva

biological

mode of vector transmission by insects or animals that carry pathogens within their bodies or through feces

acute disease

disease in which symptoms develop rapidly and runs its course quickly

chronic disease

disease with usually mild symptoms that develop slowly and last a long time

subacute disease

disease whose time course and symptoms range between acute and chronic

asymptomatic disease

disease without symptoms

latent disease

disease that appears a long time after infection

communicable disease

disease transmitted from one host to another

contagious disease

communicable disease that is easily spread

noncommunicable disease

disease not passed from person to person

local infection

infection confined to a small region of the body

systemic infection

widespread infection in many systems of the body; often travels in the blood or lymph

focal infection

infection site that serves as a source of pathogens for infections at other sites in the body

primary infection

initial infection within a given patient

secondary infection

infections that follow a primary infection often by opportunistic pathogens

incidence

number of new cases of a disease in a given area during a given period of time

prevalence

number of total cases of a disease in a given area during a given period of time

frequency; geographic

occurrence is also evaluated in terms of ______ and ______ distribution

pandemic

worldwide epidemic

epidemic

unusual cluster of cases in a particular region

sporadic disease

diseases that occur infrequently and irregularly

endemic

diseases that are consistently present within a particular geographic area or population

descriptive epidemiology

• careful tabulation of data concerning a disease

• records the location and time of the cases of disease

• collects patient info

• tries to ID the index case (first case) of the disease

analytical epidemiology

• seeks to determine the probable cause, mode of transmission, and methods of prevention

• often retrospective (investigation occurs post outbreak)

experimental epidemiology

• involves testing a hypothesis concerning the cause of a disease

• application of Koch’s postulates or other hypothesis testing

exogenous

pathogen acquired from health care environment

endogenous

pathogen arises from normal microbiota due to factors within healthcare setting

latrogenic

results from modern medical procedures

superinfections

infections on top of other infections