Infection, Infectious Diseases, and Epidemiology pt.1 Flashcards
Types of symbiosis that exist between microbes and humans
Mutualism
Commensalism
Paratism
Mutualism
both benefit, colon microbes
Commensalism
one benefits, skin microbes
Paratism
one benefits, other harmed. disease causing microbe
Normal microbiota
colonizes body surface without normally causing disease
resident
permanent
established first year of life
transient
present short period
Cant persist due to: elimination by immune system, chemical/physical changes that dislodge, microbial antagonism(competition with resident microbiota)
What opportunistic pathogens are
microbes that can cause disease under certain conditions
Conditions that enable them to cause disease
introduction into usual site:
- gut e.coli –>urethra–> UTI
- Immune surpresion
- AIDs patient
Changes in resident microbiota:
- loss of microbial antagonism
- long term antibiotic use –> yeast infection
What reservoirs of infection are
sites where pathogens maintained as source of infection
types of reservoirs of infection associated with humans
animal reservoir
human carriers
nonliving reservoirs
animal reservoir
direct contact with animal/waste, eating animals, blood sucking arthropods
human carriers
asymptomatic infected indivuals can be inefective to others
nonliving reservoirs
soil, water, food
major modes of transmission associated with infectious disease
contact transmission
vehicle transmission
vector bug transmission
contact transmission
direct contact transmission: body contact between host
indirect transmission: spreads by fomites
Droplet transmission: pathogens in droplets that travel short distances. exhaling, coughing, sneezing
vehicle transmission
pathogens travel more than 1 meter via aersol. sneezing, coughing, air-conditioning stystems, sweeping.
waterborne transmission: ingestion, gastrointestinal diseases, fecal-oral infection.
Foodborne transmission: ingestion, pathogen in and on food, inadequitly proceeded, cooked/refrigerated foods. food may become contaminated with feces.
vector bug transmission
mechanical vectors: passively transmit on their body to new host
Biological Vectors: biting insect
Major portals of entrty
skin
mucous membrane
Placenta
Skin
barrier to most microbes
entry via: hair follicle opening, gland ducts
Mucous membrane
line cavities open to outside
conjunctiva: eyelids and eyeballs
Respitory Tract: inhalation droplets, aersols and dust particles
Gastrointestinal tract: ingestion contaminated food and water
Genitourinary tract: reproductive and urinary
Placenta
connection to female. some pathogens can cross
spontaneous abortion, birth defects, premature birth
Parenteral route
not major portal
direct deposition: tissues beneath skin/mucous membranes
- blood
- puncture, injection, bite, cut, wound
