9: Parasites And Prions Flashcards
Parasite
An organism living in/on/with another organism in order to obtain nutrients, grow, or multiply - often in a state the harms the host
Three typical groups of parasites
- Protozoa
- Helminths
- Arthropods (ticks, mites, lice, etc.)
Test that can detect most parasites and how it works
Ova and Parasite test: collect stool, centrifuge, stain and examine -> ID eggs or parasites in stool
What is the prototypical protozoan parasite?
Entamoeba histolytica
Key histo finding of cryptosporidium parvum
Acid-fast oocyst in stool
How to dx malaria
Peripheral blood smear
Sickle cell and malaria
In pts with the sickle cell trait (asymptomatic), pts lack Duffy RBC Ags -> protects against plasmodium
Intestinal roundworms with lung involvement: where are they found?
Tropical and subtropical regions
Two ways to ID intestinal roundworms with lung involvement
- Stool sample
2. Respiratory specimens
What does “auto infection of larvae to lung” in threadworm infection mean?
Once the parasite is already in the body, they mature into adults in the SI, produce eggs, hatch larvae, and the larvae go back to the lungs, forming a cycle of self infection
How capture eggs in a pinworm infection
Scotch tape test
How to dx trichinella spiralis
Muscle biopsy
Pork tapeworm and beef tapeworm
Pork: taenia solium
Beef: taenia saginata
Explain prions
- PRPc: normal prion proteins, are found in the brain
2. PRPsc: abnormally folded prion proteins -> not broken down -> accumulation -> disease
What does accumulation of PRPsc cause in the brain?
Neuropil develops spongiform changes (small vacuoles)
