Test 3 Flashcards
Vectors
“zoonosis”
- disease of animals transmissible to humans
- can be direct or indirect transmission
Reservoirs
Hold pathogen between infections
- vectors, vehicles, and fomites can be reservoirs if pathogen survives in/on them and infects many individuals over time
- carriers
- always indirect because individuals are not sick
Direct transmission
Diseased and those they infect are in the same place at the same time
Must stay warm, if cook and dry no longer direct transmission
-touching
-respiratory droplets (if they remain suspended and moist)
-sexual contact
-bites (only if thing that bites you has the same disease that you get - pass same disease via bite)
-kissing
-fecal contact
Indirect transmission
Diseased not in the same place and time with those they infect
-vehicles, fomites, vectors
Vehicles
Anything taken into body voluntarily that pathogens can hitch a ride on
- contaminated food, water, air (dust)
- pathogens in dust use air to transport
Fomites
Inanimate objects
-fork, knife, spoon, table
Vectors
Living organisms (not diseased) -mosquitos carrying Zika, flies, mites, ticks
Carriers
Ex. of reservoir
Asymptomatic infected individuals who infect many overtime
-transmit directly or indirectly
-“all carriers are reservoirs but not all reservoirs are carriers”
5 stages of disease
- Incubation
- Prodromal
- Acute
- Decline
- Convalescence
Incubation phase
No symptoms, pathogen is in body and growing, immune system hasn’t recognized pathogen yet
-can be used to determine when someone should come out of quarantine
Prodromal phase
First vague symptoms appear: fever, malaise, lack of appetite)
Acute phase
Recognizable, severe symptoms
-usually when diagnosis occurs
Decline phase
Pathogen and symptoms are “declining” recognizable symptoms are still there but become less severe or less frequent
Convalescence
Symptoms gone, strength/stamina diminished
-dont have specific symptoms, but have overall weakness
Acute disease
- rapid onset (incubation and prodromal are short)
- Severe symptoms - peak of cut period has characteristic “crisis point”
- rapid recovery
Crisis point
- point during acute disease where symptoms are the worst
- if an individual is going to die they are most likely to die during this phase
Chronic disease
- delayed onset
- less severe symptoms - no crisis point, gradual transition between acute and decline
- prolonged recovery (ex. with tuberculosis, lungs will always be somewhat immunocompromised)
- never leave convalescence stage
Primary disease
- occurs in previously healthy individuals
- can make someone sick even if you are not immunocompromised
- ex. flu, strep
Secondary disease
- “piggy back” another disease, due to immunocompromised host
ex. flu (primary), pneumonia (secondary) - almost never occur on their own
- could be same pathogen gaining strength or spreading to another location (sequelae)
Sequelae
Type of secondary disease
Same pathogen gaining strength or spreading to another location
ex. scarlet fever (strep with rash) - if strep is left untreated, makes toxin that causes rash, if still gone untreated can get in blood and infect heart and kidneys
Nosocomial infection
- acquired in health care setting
- 40% of hospital deaths are from nosocomial infections
- ex. MRSA, VRE, C. Dif
Local infection
Pathogen remains at portal of entry
ex. strep, skin anthrax
Systemic infection
Spread throughout system or entire body
Septicemia
Specific type of systemic blood infection (systemic infection involving the blood)