Micro 3- principles of disease Flashcards
pathology
study of disease
etiology
the cause of a disease
pathogenesis
the development of disease
opportunistic pathogen
organisms that cause disease under specific circumstances
normal microbiota
permanently colonize the host and do not cause disease under normal conditions
transcient microbiota
may be present for days, weeks, or months and then disappear
microbiota:
-symbiosis
the relationship between normal microbiota and the host
microbiota:
-commensalism
one organism benefits, and the other is unaffected
ex: staphylococcus epidermis (skin), corynebacteria (eye)
microbiota:
-mutualism
both organisms benefit
E coli synthesize vitamin K and some B vitamins
microbiota:
-parasitism
one organism benefits at the expense of the other
microbiotal antagonism (competitive exclusion)
is a competition between microbes
how do normal microbiota protect the host by
- competing for nutrients
- producing substances harmful to invading microbes (bacteriocins)
- affecting pH and available oxygen
bacteriocins
proteins that inhibit the growth of other bacteria
what does it mean that some normal microbiota are opportunistic pathogens
they don’t cause disease in their normal habitat in a healthy person
examples of how opportunistic pathogens can work
- unhealthy or compromised host
- infection outside its normal habitat
what are koch’s postulates used to prove
used to prove the cause of an infectious disease
4 Koch’s postulates
- the same pathogen must be present in every case of the disease
- the pathogen must be isolated from the diseased host and grown in pure culture
- the pathogen from the pure culture must cause the disease when its inoculated into a healthy, susceptible lab animal
- the pathogen must be isolated from the inoculated animal and must be shown to be the original organism
exceptions to koch’s postulates
- some pathogens can cause several disease conditions (mycobacterium tuberculosis)
- some pathogens cause disease only in humans (HIV)
- some microbes have never been cultured (syphilis, leprosy)
symptoms are
changes in body function that are felt by a patient as a result of a disease
ex: pain, malaise
signs are
changes in body that can be measured or observed as a result of a disease
ex: fever, purulent discharge
syndrome
a specific group of signs and symptoms that accompany a disease
communicable disease
a disease that is spread from one host to another
ex: chickenpox, measles, influenza, genital herpes, typhoid fever, tuberculosis
contagious disease
diseases that are easily and rapidly spread from one host to another
ex: chickenpox, measles
noncommunicable disease
a disease that is not spread from one host to another
ex: tetanus
incidence of a disease
number of people who develop a disease during a particular time period
-indicates spread of a disease
prevalence of a disease
number of people who develop a disease at a specified time, regardless of when it first appeared
-indicates spread of a disease (takes into account old and new cases)
acute disease
symptoms develop rapidly but the disease lasts only a short time
chronic disease
symptoms develop slowly
ex: tuberculosis, infectious mononucleosis, hepatitis B
latent disease
causative agent is inactive for a time but then activates and produces symptoms
sporadic disease
disease that occurs only occasionally
ex: typhoid fever in US
endemic disease
disease constantly present in a population
ex: common cold
epidemic disease
disease acquired by many people in a given area in a short time
ex: influenza or AIDS
pandemic disease
worldwide epidemic
ex: influenza and AIDS
local infection
pathogens are limited to small areas of the body
ex: boils and abscesses
systemic (generalized) infection
infection throughout body
ex: measles
focal infection
systemic infection that began as local infection, confined to specific area
ex: infections in teeth, tonsils or sinuses
sepsis
toxic inflammatory condition raisins from the spread of microbes, especially bacteria or their toxins, from a focus of infection
septicemia
also known as blood poising, growth of pathogens in the blood (an example of sepsis)
bacteremia
bacteria in the blood
toxemic
toxins in the blood
viremia
viruses in the blood
primary infection
acute infection that causes the initial illness
secondary infection
opportunistic infection after a primary (predisposing) infection
subclinical disease
no noticeable signs or symptoms (inapparent infection)
what types of reservoirs of infection can you have
- human reservoirs
- animal reservoirs
- nonliving reservoirs
human reservoirs
carries may have inapparent infections or latent diseases
ex: AIDS, typhoid fever
animal reservoirs
zoonoses are diseases transmitted from animals to humans
ex: rabies, lyme disease, malaria)
nonliving reservoirs
- soil (clostridium botulinum - botulism, clostridium tetani - tetanus)
- water (virbir cholera - cholera, cryptosporidium - diarrhea, salmonella typhi - typhoid fever)
direct contact transmission
requires close association between the infected and a susceptible host
ex: staphylococcal infections and STDs
indirect contact transmission
spreads to a host by a nonliving object called a famine
ex: contaminated syringes in AIDS and hepatitis B
droplet transmission
transmission via airborne droplets less than 1 meter
ex: influenza, pneumonia ana pertussis
vectors
arthropods, especially fleas, ticks, and mosquitos
-transmit disease by two general methods: mechanical, biological
mechanical transmission of vectors
arthropod carries pathogen on its feet, passive transport
biological transmission of vectors
pathogen reproduces in the vector, transmitted via bites or feces, active transport
vehicle transmission
transmission of a disease agent by a medium (inanimate reservoir)
- waterborne (cholera)
- foodborne (food poisoning, tapeworm)
- airborne (tuberculosis)
recipe for nosocomial infections/ HAIs
- microorganisms in the hospital environment
- weakened status of the host
- chain of transmission in a hospital
