C-8 Flashcards
epidemiology
The study of the occurrence and spread of disease and how it can be prevented or limited
etiology
The cause of disease or infection
incidence
Number of new cases of a disease in a given area/population in a given period of time; tells you what the risk of acquiring the infection is
prevalence
Total number of all individuals affected by the disease in an area at a particular time
(includes both new and old cases); tells you how widespread the disease is
morbidity
Another term for disease but not deaths (can include incidence and prevalence)
mortality
death due to disease
endemic
expected disease that normally
occurs at regular intervals at stable incidence within a given population or area (i.e. flu)
sporadic
disease with only a few scattered cases within a population or area; occurs
infrequently and irregularly (i.e. rabies)
epidemic
disease that occurs at a greater
frequency than is normal/usual for an area or population. Can be endemic!
pandemic
if an epidemic occurs
simultaneously worldwide (on multiple continents) (i.e. covid)
reservoirs
Sites where pathogens are normally maintained and act as a source of infection
portals of entry and exit (skin, mm, placenta)
skin: broken skin, natural openings, hair follicles and sweat glands, insect bites or burrowing
mm: Line the GI, respiratory, urinary, and reproductive
tracts – also line the eyes, nose, and mouth; Thinner and easier to penetrate
placenta: Barrier between fetus and mother – some pathogens can cross
direct transmission (contact)
Ex. Handshake, kissing,
intercourse, placenta,
unwashed hand to own mouth
indirect transmission (contact)
- Ex. Touching a fomite - toothbrush, drinking glass, money
- Puncture wound
droplet transmission (contact)
- Larger droplets from an
aerosol less than 1 meter away - Ex. Droplets from sneezing
mechanical transmission (vector)
don’t act as hosts for the
pathogens they transmit – only
passively carry pathogens to new hosts on feet or other body parts (flies and cockroaches)
biological transmission (vector)
transmit pathogens and serve as hosts for the multiplication of a pathogen during its life cycle (biting - mosquitos, lice, ticks, mites, etc)
airborne transmission (vehicle)
Transmitted by the air. Farther distance than droplet transmission; finer aerosolized particles. Ex. fungal spores or measles virus
waterborne transmission (vehicle)
Many GI diseases are waterborne caused by fecal
contamination of drinking water (fecal-oral infection).
Ex. cholera
foodborne transmission (vehicle)
Similar to waterborne – Ex. produce contaminated with
fecal matter from animals; parasitic worms from undercooked meat
bodily fluid transmission (vehicle)
Bodily fluid from infected individuals can also be a
source of transmission.
Ex. semen or blood
fomite
inanimate object
pathogenicity vs virulence
The ability to cause disease vs The degree of pathogenicity
pathogen
microbes that are able to cause disease
opportunistic pathogen
microbes that don’t normally cause disease unless an opportunity arises like a compromised immune system or weakened microbiome
virulence factor
Characteristics of pathogenic
microbes that allow them to be pathogenic/virulent
how a capsule affects virulence and survival in the human body
Prevents phagocytes from
ingesting/killing pathogenic
bacteria
how exotoxins and endotoxins affect virulence and survival in the human body
Cytotoxins inhibit protein
synthesis and destroy cells
(Diptheria toxin)
Neurotoxins prevent nerve
transmission (Botox)
Enterotoxins promote fluid loss
from cells (cholera toxin)
LPS – pyrogen and can induce
inflammation and shock
how enzymes (and other extracellular products and components like adhesions) affect virulence and survival in the human body
Help pathogenic bacteria
invade deeper tissues and
evade immune response
Describe how we experimentally determine how something is a virulence factor
need to assess whether it is necessary and/or sufficient for a
microbe to cause disease;
necessary: make a deletion mutation in that gene and
see if the microbe is still able to cause disease
sufficient: add that protein into another microbe’s genome and see if that protein is all a microbe needs to cause disease
infection vs disease
infection: A progression of contamination – where contaminating microbes have
invaded the body, overcome immune defenses, and multiplied
disease: When an infection adversely affects the body and health
stages of infectious disease
- incubation period (microbes replicating
- prodromal period (pathogen multiplying and host feels illness)
- period of illness (signs and symptoms most severe)
- period of decline (signs and symptoms suppress)
- period of convalescence (recovery)
signs vs symptoms
signs: Objective manifestations of disease observed or measured by those other than the patient (outside observations)
symptoms: Subjective characteristics of a disease that are only felt by the patient
HAI
hospital acquired infections (dirty beds, linen, handling patient to patient, etc)
how HAI arise
exo: infection acquired form others in health care environment
endo: acquired opportunistic infection from hospitalization or chemotherapy
prevention and control methods of HAI
- Disinfect surfaces/good housekeeping
- Handwashing
- Bathing / hygiene
- Proper food handling
- Aseptic practices in surgery/procedures
- Isolation of contagious or
vulnerable patients
innate (nonspecific) immune
first and second lines of defense
phagocytosis
cell eating
roles of eosinophils in innate immunity
Phagocyte/Microphage - involved in parasitic infection; Degranulate to secrete antimicrobial chemicals to
kill pathogens too big to be ingested
roles of neutrophils in innate immunity
Phagocyte/Microphage - releases cytotoxic chemicals like ROS; Degranulate to produce reactive oxygen species
(ROS, trigger inflammation, produce NETs
roles of NK cells in innate immunity
Degranulate and secrete toxins called perforins and granzymes onto the surfaces of virally infected cells and tumor cells marked for destruction
inflammation (How are basophils and molecules like histamines, prostaglandins, and leukotrienes involved? What are the consequences of too much inflammation?)
response to tissue damage and infection; the molecules help stimulate inflammations; HIPER (heat, induration, pain, edema, and redness)
complement (opsonization and MAC)
collection of serum proteins that form MAC and do opsonization; MAC= membrane attack complex that punches holes in gm- membranes; opsonization=enhances abilities of antibodies and phagocytes to clear infection
interferons (how do they specifically interfere with viral infections)
signaling proteins by host cells infected by viruses to warns other cells that viruses are coming (type 1 and type 2)
fever (purpose, pyrogens, too much fever)
fever increases body temp to kill or inhibit microbial growth; pyrogens trigger hypothalamus to reset the body’s thermostat to higher temps to enhance inflammation; too much fever=can damage normal, good cells (DNA damage, membrane damage, cellular damage, too much inflammation, bacteria can enter blood stream rather than just exit, losing BP)
animal reservoirs
Responsible for spreading
zoonoses – diseases that spread from animals to humans
human carries
People who incubate the pathogen in their bodies; some become sick and others don’t
nonliving reservoirs
Inanimate things like soil, water,
food, can harbor pathogens
