Chapter 14-Infection Flashcards
symbiosis
to live together
types of symbiosis
mutualism, commensalism, parasitism
mutualism
both members benefit
commensalism
one member benefits without affecting the other
parasitism
parasite benefits while host is harmed
normal microbiota
microbes that colonize the surfaces of the body without causing disease
types of normal microbiota
resident and transient
resident microbiota
remain as part of the host for life
transient microbiota
remain in the host for a certain amount of time before disappearing
opportunistic pathogens
normal microbiota may become harmful if the opportunity arises
conditions which create opportunities for microbiota to become pathogenic
normal microbiota in different site than usual; immune suppression; changes in number of normal microbiota
reservoirs of infection
sites where pathogens are maintained as a source of infection
types of reservoirs
animal reservoirs, human carriers, and nonliving reservoirs
animal reservoirs
zoonoses; spread from animal hosts to humans
human carriers
human source of infection
nonliving reservoirs
soil, water, and food
contamination
presence of microbes in or on the body
infection
microbes that overcome the body’s external defenses and invade the body
portals of entry
sites in which most pathogens enter the body
four portals of entry
skin, mucous membrane, placenta, parenteral route
adhesion
process by which microbes attach to cells using adhesion factors
adhesion factors
specialized structures or attachment proteins
ligands
enable them to bind to complementary receptors on host cells
avirulent
bacterial cells that have lost ability to make ligands, making them harmless
disease
when an infection is significant enough to interfere with normal body function
morbidity
any change from state of health
symptoms
subjective characteristics of a disease felt by the patient alone
examples of symptoms
pain, headache, dizziness, and fatigue
signs
objective manifestations of disease that can be seen by others
examples of signs
swelling, rash, redness, and fever
syndrome
group of symptoms and signs that characterize a disease
asymptomatic
infections with no symptoms
congenital disease
diseases present at birth regardless of the cause
etiology
study of the cause of a disease
pathogenicity
ability of a microorganism to cause disease
virulence
degree of ability to cause disease
virulence factors
factors that interact with a host and enable the pathogen to enter a host
three virulence factors
extracellular enzymes, toxins, and antiphagocytic factors
extracellular enzymes
enzymes that enable them to dissolve structural chemicals in the body
four types of extracellular enzymes
hyaluronidase, collagenase, coagulase, kinases
hyaluronidase
digests hyaluronic acid that holds animal cells together
collagenase
breaks down collagen
coagulase
causes blood proteins to clot
kinases
digests blood clots
toxins
chemicals that harm or trigger host immune responses that cause damage
types of toxins
exotoxins and endotoxins
exotoxins
destroy host cells or interfere with host metabolism
types of exotoxins
cytotoxins, neurotoxins, and enterotoxins
cytotoxins
kill host cells in general or affect function
neurotoxins
interfere with nerve cell function
enterotoxins
affect cells lining the GI tract
antitoxins
protective molecules that bind to toxins and neutralize them in the body
toxoids
toxins treated to make them nontoxic but still capable of stimulating antibody productions
endotoxins
lipid A from lipopolysaccharide of Gram-
two types of antiphagocytic factors
capsules and antiphagocytic chemicals
antiphagocytic chemicals
chemicals produced by some bacteria that prevent fusion of lysosomes with phagocytic vesicles
incubation period
time between infection and first sign or symptom, depends on virulence factor
prodromal period
short time of generalized, mild symptoms that precedes illness
illness
most sever stage; signs and symptoms are most evident
decline
immune response and/or treatment fight off pathogen
convalescence
recovery from illness
modes of infectious disease transmission
contact transmission, vehicle transmission, and vector transmission
types of contact transmission
direct, indirect, and droplet
direct contact transmission
body contact between hosts
indirect contact transmission
pathogens are spread by fomites
fomites
inanimate objects that are used to transfer pathogens to hosts
droplet transmission
droplets of mucus that exit body during respiratory processes
types of vehicle transmission
airborne, waterborne, and foodborne
airborne transmission
spread of pathogens farther than one meter to the respiratory mucous membrane of host via aerosol
waterborne transmission
water acts as a reservoir as well as a vehicle of infections
foodborne transmission
pathogens in or on food that is inadequately processed, undercooked, or poorly refrigerated
vector transmission
animals that transmit diseases from one host to another
types of vector transmission
biological and mechanical vectors
biological vectors
transmit pathogens and serve as hosts for reproduction
mechanical vectors
passively carry pathogens to new hosts on body parts
acute disease
develops rapidly but lasts for short time
chronic disease
develops slowly and lasts long time, sometimes recurrent
subacute disease
durations and severities that are between acute and chronic
latent disease
pathogen remains inactive for long time before becoming active
communicable disease
infectious disease comes directly or indirectly from another host; contagious disease
noncommunicable disease
source of infectious disease is not a host
epidemiology
study of where and when disease occur and how they are transmitted
incidence
number of new cases in a given area during a given time
prevalence
total number of cases, new and old, in a given area during a given time
endemic
disease that normally occurs continually in a given area
sporadic
few scattered cases occur in an area or population
epidemic
disease that occurs more than normal for an area
pandemic
epidemic occurring at the same time on more than one continent
descriptive epidemiology
careful recording of data concerning a disease including: location, time, ages, gender, occupations, and health histories
index case
the first case of a disease
analytical epidemiology
determines the probable cause of disease; retrospective
experimental epidemiology
testing a hypothesis resulting from analytical epidemiology
nosocomial infections
acquired by patients or health care workers in health care facilities
nosocomial diseases
diseases acquired in a health care setting
types of nosocomial infections
exogenous, endogenous, and iatrogenic
exogenous nosocomial infections
caused by pathogens acquired from the health care environment
endogenous nosocomial infections
arise from normal microbiota that become opportunistic within a health care setting
iatrogenic infections
nosocomial infection that is direct result from modern medical procedures
