BIOL 437 Week Two Part 2 Flashcards
exposure examples
- micro-organism
- tobacco components
incumbation/latency period
- stage of subclinical disease when individual is unaware of pathological changes that are occuring
- asymptomatic
- variable duration
incubation period
- infectious disease
- some pathological changes can be detected with specific tests
- interventions most effective at this stage before symptomatic
latency period
-chronic conditions
onset of symptoms
- transition from subclinical to clincal disease
- when most diagnoses are made
spectrum of disease
- variability of severity from mild to severe
- disease process ends with recovery, disability or death
infectivity
-the proportion of exposed persons who become infected
pathogenicity
-the proportion of infected individuals who develop clinically apparent disease
virulence
-the proportion of clinically apparent cases that are severe of fatal
carrier state
-individuals who are infectious but have subclinical disease (incubating disease)
>have an inapparent infection who never shows symptoms
-individuals who have recovered from clincial illness but remain infectious
iceberg concept
- recognizes the importance of inapparent cases
- host and cell level
clincial disease
-signs and symtoms evident
non-clinical (inapparent) disease types
- Preclinical
- Subclinical
- Persistant (chronic)
- Latent
preclinical
-will become clinical
subclinical
-diagnosed with serology or culture
persistant (chronic)
-infection persists
latent
-infection with no active agent replication
>not a risk to other individuals
carrier status
- individual ‘hosts’ the organism but is not infected
- no serological evidence of antibody
- limited duration or chronic
- able to infect others
Typhoid Mary (Mary Mallon)
- carrier for samonella
- caused at least 10 typhoid fever outbreaks
- was a cook in NYC
viability
- the capacity of the pathogen or disease-causing agent to survive outside the host and to exist in the environment
ex. guinea worm is 1 year, must break the cycle for 1 year
5 major disease categoreies
- Congenital and hereditary diseases
- Allergies and inflammatory diseases
- Degenerative diseases
- Metabolic disease
- Cancer
congential
-at birth
cogenital and hereditary diseases
- spontaneous developmental abnormalities (ex. some forms of Down Syndrome, congenital hypothyroidism)
- familial tendenceies toward certain inborn abnormalities and inherited conditions (eg. colourblindness, some forms of breast cancer)
- injury to the enbryo or fetus by environmental factors (eg. thalidamide, radiation, opoids)
allergies and inflammatory diseases
- body reacting to an invasion of or injury by a foreign object or substance
- includes diseases caused by pathogens (communicable and non-communicable)
any foreign object
-can act as an allergen which activates the immune system
degenerative diseases
- deterioriation of body systems, tissue and functions
- often associated with the aging process
metabolic diseases
- casue the dysfunction, poor function, or malfunction of certain organs or physiological processes within the body leading to disease states
ex. cells may no longer utilize glucose normally causing diabetes
cancer
-characterized by abnormal growth of cells from a variety of tumours, both benign and malignant
chain of infection
- reservoirs/hosts
- portal of exit
- mode of transmission
- portal of entry
- susceptible host
modes of transmission
- direct contact
- vector
- vehicle
- droplet
- airborne
reservoirs
- habitiat in which an agent lives, grows and multiplies
- humans, animals, the environment
- may or may not be the source from which the agent is transferred to the host
human reservoirs
- many diseases
- person-person transmission (eg. measels, mumps, STDs)
- may or may not show illness effects
types of human reservoirs
- asymptomatic healthy carriers
- incubatory carriers
- convalescent carriers
animal reservoirs
- animal-animal
- humans as incidental hosts
- zoonosis
- newly recognized human diseases that are thought to have emerged from animals hosts (Ebola, SARS)
zoonosis
- infectious disease transmissilbe from vertebrate animals to humans (Ex. rabies)
- newly emergent in N. America (ex. monkeypox: prarie dogs)
environmental reservoirs
- plants
- soil
- water
portal of exit
-path by which a pathogen leaves its reservior hosts
examples of portal of exits
- respiratory tracts
- urinary tracts
- GI tracts
- skin lessions
- conjuctival secretions (eye)
- cuts/needles
- crossing placenta
modes of transmission
- direct
- indirect
direct
- direct contact (touch, bodily fluids)
- droplet spread
indirect
- airborne
- vehicle borne
- vector borne
common vehicles
- contaminated air
- water
- food
- fomites (objects)
vector borne
- fly, fleas, mosquitos
- mechanical or biological
biological vector borne
-pathogen changes as part of its life cycle within the vector
zika virus
-mosquito as vector (indirect)
influenza virus
- person-person (direct)
- air borne and fomites (indirect)
portal of entry
- how the pathogen enters a susceptible host
- access to tissues where pathogen can multiply or toxin can act
- may be the same portal as portal of exit from reservoir
- fecal, skin, mucous membranes, blood
common modes of entry
- respiratory
- oral
- reproductive
- intravenous
- urinary
- skin
- GI
- conjuctival
- transplacental
susceptible host
- genetics
- specific immunity
- nonspecific defenses
- malnutrition
- alcoholism
- concurrent diseases
