General- parasites Flashcards
What are Sarcodina?
Ameba (protozoa)
What are Mastigophora?
Flagellates (protozoa)
What are Ciliophora?
Ciliates (protozoa)
What are Sporozoa?
Protozoa that are nonmotile in adult stage
What are the categories of helminths?
- Flat worms/platylhelminths (trematodes and cestodes)
- Thorny-headed worms/acanthocephalins
- Roundworms (nematodes)
- Segmented worms (annelids)
What are ectoparasites?
Blood-sucking ectoparasites, fleas, ticks, lice, mites, etc. that burrow into skin and remain for a long time. May serve as vectors of other pathogens.
Which parasites can be cultured? What do they usually cause?
Acanthamoeba species and Naegleria fowleri; CNS and ocular infections
Common causes of acanthamoeba
Eye contact contamination causing ocular infection (e.g. dirty hands)
Which parasite may be seen in routine bacterial culture?
Strongyloides (note: not cultured this way)
Which parasite can cause CNS infection by Gram-negative rods? How?
Strongyloides; tissue invasion may bring GI flora into bloodstream (note: Gram-negative rods may cause meningitis in neonates and children without Strongyloides infection)
How is a Giemsa stain performed?
Drop of blood is hemolyzed for visualization of intracellular organisms. in thick smear. Thin smear is not hemolyzed, but morphology is preserved.
How many specimens are needed to check for parasites in a stool O&P?
3 specimens on 3 separate days.
Which parasites cannot be identified on stool O&P?
- Cryptosporidium
- Cyclospora
- Cystoisospora
- Microsporidia
Which stain is used if cryptosporidium is suspected?
Acid-fast stain (EIA or DFA can also be used)
When is stool antigen testing the optimal choice?
Giardia, Cryptosporidium, and Entamoeba (antigen testing also available for Plasmodium species)
Which parasites can be detected by serology?
Strongyloides, Entamoeba histolytica (disseminated only)
Loa loa (microfilariae)- Presentation
Swelling in skin; worm in conjunctiva
Loa loa (microfilariae)- Labs
Blood smear/Giemsa
