T3- Epidemiology of Infectious Diseases Flashcards
Define flora/microflora.
Microorganisms present on the surface of AND within the body.
What is the term to describe flora that has no adverse effects?
Commensalism
What is the term to describe flora that benefits the host?
Mutualism
Why are flora useful?
They can compete with disease-producing microorganisms, thus inhibiting their growth.
What are the 3 ways pathogens cause disease?
Direct destruction of host cell
Interference with host cell metabolism
Exposure of host cell to toxins
What is a prion?
It is a protein that causes infection. It is just mutated protein particles, but causes incurable and 100% fatal diseases such as Creutzfeld-Jakob Disease, kuru, and bovine spongiform encephalopathy (mad cow disease)
What is the mechanism behind prions?
They interact with normal proteins and cause the normal ones to turn into more infected ones. They generally accumulate in nerve cell axons, causing slow but progressive NONinflammatory neuronal degeneration.
What is a virion and capsid?
Virion refers to the entire virus particle.
Capsid is a protein coat found on all viruses.
Note:
We can just inject some proteins from a capsid for vaccines instead of the entire virus.
What does not always surround a virion?
Lipoprotein envelope
What are obligate intracellular pathogens?
They bind to receptors on host cells, entering it and converting the host cell’s metabolism to make more viral nucleic acids and proteins instead.
Eventually, the cell goes haywire and undergoes lysis.
What period do viruses sometimes undergo prior to symptoms? What is a famous virus that works like this?
Latency period. HIV is a prime example of a virus with a latency period, in which there are little to no symptoms.
What are the layers of a typical virus?
Superficial to deep:
Glycoproteins
Lipoprotein Envelope (optional)
Tegument
Capsid
DNA/RNA core
What are the two types of metabolism for bacteria?
Aerobic and anaerobic.
What does it mean to be facultatively anaerobic?
They can switch between aerobic and anaerobic.
What is a key difference between virus and bacteria replication?
Viruses require hosts. Bacteria can live on their own.
What is a key distinguishing factor between a bacteria and a human cell?
Cell walls made of peptidoglycan. Human cells lack this cell wall.
What organelles do bacteria lack compared to human cells?
No organized nucleus
Mitochondria
Endoplasmic reticulum
What is a plasmid?
A circular strand of DNA that replicates independently of chromosomes.
How do bacteria move around?
Flagella
How do bacteria stick to things?
Pili
Where do we have a lot of bacteria in our body?
GI tract, which is anaerobic.
What 3 things do we generally categorize bacteria by?
Shape (cocci, bacili, spirochete, spirilla)
Grouping (diplo, strepto, staphylo)
Staining (G+, G-, acid-fast)
What is the difference between an endotoxin and exotoxin?
Endotoxins are the physical remnants of bacteria that can produce an immune response.
Exotoxins are what bacteria make, often as a byproduct of their metabolism.
What is an endospore?
A dormant bacteria that has been reduced down to a simpler form. It is way more resistant to everything and requires reactivation later.
What color are G+ bacteria usually?
Purple
What color are G- bacteria usually?
Pink
What kind of infection is a fungal infection?
A mycotic infection.
What are the two types of mycoses?
Superficial, limited to surface areas of the body.
Deep, invading deep tissue.
Where do I usually find fungi?
Skin and mucous membranes. They can become opportunistic pathogens.
Whats the difference between yeast and mold?
Yeast are UNIcellular (you and u)
Mold are multicellular (M and M)
Yeast reproduce via budding and pseudohyphae.
Mold reproduce via hyphae.
They can all form spores which are highly resistant.
What are protozoa?
Unicellular, complex organisms with a nucleus and organelles.
They usually have motility and spend part of their life outside of humans.
What diseases do protozoa cause?
Malaria
Toxoplasmosis
Trichomoniasis
Giardiasis
Amoebiasis
How are protoza transmitted?
Direct host-host contact
Contaminated food/water
Arthropod vectors
Note:
They can also form cysts to aid in transmission.
What are helminths?
Wormlike parasites
What is included in helminths?
Nematodes (roundworms)
Cestodes (tapeworms)
Trematodes (flukes)
How are helminths transmitted?
Ingestion of fertilized eggs
Penetration of skin by larvae
Arthropod vectors
Where are helminths most commonly found?
Developing countries
What are the ectoparasites?
Things that infest external body surfaces.
Mites (scabies), chiggers, lice, flea
How are ectoparasites transmitted?
Contact with arthropods or larvae/egg forms.
What kind of bacteria is rickettsiae?
G-, obligate intracellular pathogen.
What is unique about rickettsiae?
Infects arthropod vectors, but does NOT cause any disease in them