CH 14: Infection, Infectious Disease, Epidemiology

Which of the following is an example of mutualism?

bacteria living in the human colon

Humans acquire normal microbiota in all of the following ways except

in the womb

All of the following are examples of zoonotic diseases except

chicken pox

Which of the following types of toxins are produced only by Gram-negative bacteria?

endotoxins

___________ is not an example of direct contact transmission of disease.

Sharing a drinking glass

When a housefly walks across feces containing Salmonella and then walks across food, the fly is serving as a

mechanical vector

____________ is a relationship in which both members benefit.

Mutualism

What is a zoonotic disease?

A disease that can spread from animals to humans

Why are bacterial capsules effective as virulence factors?

Capsules enable pathogens to “hide” from the immune system

Which of the following is a definition of disease transmission by fomites?

Transmission by inanimate objects

What term best describes the total number of disease cases in an area during a given period of time?

Prevalence

Symbiosis

live together

Mutualism

benefits both

commensalism

benefits organism #1, doesn’t harm or benefit #2

Amensalism

harms #1, doesn’t harm or benefit #2

Parasitism

benefits #1, harms #2

Microbiome of humans

organisms that colonize body’s surfaces without normally causing disease

redisent microbiota

part of normal microbiota throughout life. mostly commensal

transient microbiota

remain in body for short period, found in same regions as resistant microbiota, cannot persist in body

acquisition of microbiome

develops during birth, most established during first months of life

opportunistic pathogens

normal microbiota that cause disease under certain circumstance

reservoirs

sites where pathogens are maintained as source of infection

Animal reservoirs/zoonoses

humans are dead-end hosts, hard to eradicate, transmitted by direct contact with animal waste, eating animals, blood sucking arthropods

human carriers

asymptomatic infected individuals

non-living reservoirs

soil, water, and food due to contamination by feces or urine

contamination

mere presence of microbes

infection

when organism evades body’s external defenses, multiplies, becomes established in the body

portals of entry

skin, mucous membranes, placenta

adhesion

microorganisms attach themselves to cells

pathogenicity

ability of microorganisms to cause diseasev

virulence

degree of pathogenicity

virulence factors

adhesion factors, biofilms, extracellular enzymes, toxins, antiphagocytic factors

extracellular enzymes

secreted by pathogen, dissolve structural chemicals in body, help pathogen maintain infection, invade, avoid body defenses, important to virulence

avirulent

do not secrete enzymes

toxins

chemicals that harm tissues or trigger host immune responses that cause damage

two types of toxins

endotoxins, exotoxins

Toxemia

presence of toxins in the bloodstream

antiphagocytic factors

prevent phagocytosis, allows pathogens to remain in host for long time

bacterial capsule

chemicals not recognized as foreign, slippery + difficult to engulf

antiphagocytic chemicals

prevent fusion of lysosome and phagocytic chemicals

incubation period

no signs/symptoms, before prodromal

prodromal period

vague/general symptoms

illness

most severe signs and symptoms

decline

declining signs and symptoms

convalescence

no signs or symptom, after decline

symptoms

characteristics felt only by patients

signs

manifestations observed or measured by others

syndrome

symptoms + signs that characterize a disease or abnormal condition

asymptomatic/subclinical

lack symptoms, may have signs of infection

etiology

study of cause of disease

hereditary

errors in genetic code

congenital

birth defects

degenerative

aging

nutritional

lack of essential nutrients in diet

endocrine

excess or deficiencies of hormones

mental

emotional or psychosomatic

immunological

hyperactive or hypoactive immunity

neoplastic (tumor)

abnormal cell growth

infectious

caused by infectious agent

iatrogenic

caused by medical treatment/procedures

idiopathic

unknown cause

healthcare-associated

acquired in healthcare setting

Robert Koch

postulates to prove pathogen causes disease

Germ theory of disease

infections by pathogenic microorganisms cause disease

transmission

form a reservoir or portal of exit to another host’s portal of entry

three groups of transmission

contact, vehicle, vector

direct contact transmission

body contact or self-contact

indirect contact transmission

spread by fomites

droplet transmission

droplets of mucus 

airborne transmission

when pathogens travel 1+ meter via aerosol

waterborne transmission

spread gastrointestinal diseasesf

foodborne transmissions

inadequately processed, cooked, refrigerated foods

bodily fluid trasmission

blood, urine, saliva contact the skin or mucus membranes

biological vectors

transmit pathogens, serve as host for some stage of pathogen’s life cycle

mechanical vectors

passively transmit pathogens present on body to new hosts

classification of disease

taxonomic categories, body system they affect, longevity + severity, how they spread, effects on populations

incidence

# of NEW cases in a given area during a given period

prevelance

# of TOTAL cases in a given area during a given time period

occurence

frequency and geographic distribution

exogenous

acquired from health care environment

Endogenous

arises from normal microbiota

superinfections

use of antimicrobial drugs inhibit some resident microbiota, allowing other microbes to thrive

acute disease

symptoms develop rapidly and runs its course quickly

chronic disease

usually mild symptoms that develop slowly and last a long time

subacute disease

time course and symptoms range between acute and chronic

asymptomatic disease

no symptoms

latent disease

appears a long time after infection

communicable disease

transmitted from one host to another

contagious disease

easily spread

noncommunnicable disease

not passed from person to person

local infection

confined to a small region of the body

systemic infection

many systems of the body, travels in blood or lymph

focal infection

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

primary infection

initial infection with a given patient

secondary infection

follows primary infection, often by opportunistic pathogens