Wk 1 Infection Flashcards
Infection
colonization of a host by a microbial species
Localized
in a specific place
Systemic
spread to several regions/areas of the body
Common cause of infection
- virus - only DNA or RNA, surrounded by a protein shell, must have a host cell
- bacteria = much larger than a virus, single-celled organism
Rare causes of infection
- fungal = spore forming organisms
- protozoa = typically live in water/environment = malaria
- helminths - parasitic worms
- prions = rarest, proteinaceous infectious particles, only composed of protein, ex is mad-cow disease
Modes of transmission
microorganism must have a reservoir –> habitat where they usually live and grow (can be human, animal, insect, environment)
Direct transmission
kissing, sex, direct contact with contaminated soil or vegetation, droplet
Indirect transmission
airborne (droplet stay suspended in air), vehicle or vector born
Vehicle born
indirect transmit from food, water, or blood
Vector born
when something else carries the disease, like mosquitoes carry malaria
Portal of entry
how they get into the body
- oropharynx or nasopharynx (bronchial airways, lungs, stomach or GI tract)
- genitourinary tract (urinary tract)
Body’s biggest barrier
skin
Translocation
movement of bacteria across the intestinal lining
- occurs frequently in the peritoneal cavity
- bloodstream (like infection in your blood, then blood takes it to your bones)
Blood
blood transfusion contamination or needlestick
Maternal-fetal transmission
- some microorganisms can cross the placental barrier and get directly to the fetus
- some can occur during childbirth
Stages of Infection
- Incubation
- prodromal
- period of illness
- period of decline
- period of convalescence
- resolution
Incubation period
time from when that microorganism gets into the body and when symptoms first appear
Prodromal stage
onset of non-specific symptoms
Acute stage
period of illness
- full-blown
Convalescent stage
coming out of acute stage, symptoms getting better
Resolution phase
pathogen is completely eliminated from your body
- some infectious agents never get to this stage, like chickenpox laying dormant in your body
The infectious/inflammatory process
- injury
- increased permeability
- immigration of leukocytes
- phagocytosis
- exudate
- systemic symptoms
Injury
- initial insult to area occurs
- short period of vasoconstriction (very short so you stop bleeding and prevent movement of invading organisms)
- Prolonged period of vasodilation
Injury + Vasodilation
- allows blood to flow freely to the area
- brings immune cells to the area
- contributes to symptoms of inflammation such as warmth, redness, and swelling