Parasitology Exam 2 Flashcards
- eggs can be mamalated (bumpy) or smooth when fertilized
- eggs are barrel-shaped when unfertilized
- requires both male and female worm present to fertilize
Ascaris lumbricoides
Ascaris lumbricoides: Diagnostic and Infective
Diagnostic: eggs
Infective: eggs
- eggs have “flat football” appearance (one flat side)
- eggs collected from the peri-anal area with a sticky-sided spatula
Enterobius vermicularis (Pinworm)
Enterobius vermicularis: Diagnostic and Infective
Diagnostic: eggs
Infective: eggs
- eggs have distinctive “polar plugs” and are barrel-shaped
- light amber color on bile stain
Trichuris trichuria (Whip worm)
Trichuris trichuria: Diagnostic and Infective
Diagnostic: eggs
Infective: eggs
- eggs have granular cluster of larvae with visible space between them and the cell wall
- two organisms have the same egg morphology
Ancylostoma duodenale (Old World Hookworm)
Necator americanus (New World Hookworm)
Hookworm: Diagnostic and Infective
Diagnostic: eggs
Infective: filariform larva penetrates skin
“Worm burden”
a measure of how many hookworms are in the gut, can relate to the severity of iron deficiency anemia that may develop from chronic bleeding
Differences in adult hookworm morphology
- Ancylostoma duodenale has 2 pairs of teeth for attachment
- Necator americanus has two cutting plates for attachment
Differences between strongyloides and hookworm rhabditiform larvae
- Strongyloides has short buccal cavity
- Hookworm has long buccal cavity
Which nematode can cause autoinfection?
Strongyloides stercoralis
Strongyloides stercoralis: Diagnostic and Infective
Diagnostic: rhabditiform larvae
Infective: filariform larva penetrates skin
Usually obtained from infected animal tissue, especially raw pork. “Wood knots” appearance in tissue
Trichinella spiralis
Trichinella spiralis: Diagnostic and Infective
Diagnostic: Larvae in tissue
Infective: encysted larvae in undercooked meat
Adult worm releases larvae from a blister on the leg or foot. Eliminated by slowly winding on a stick.
Dracunulus medinensis
Dracunulus medinensis: Diagnostic and Infective
Diagnostic: Blister bursting
Infective: ingesting copepods in water
- Causes elephantiasis of the lower extremities
- Microfilariae in the blood have a sheath, but no nuclei in the tip of the tail
Wucheria bancrofti
Wucheria bancrofti: Diagnostic and Infective
Diagnostic: microfilaria in blood
Infective: skin penetration of microfilariae by insect vector (Anopheles)
- Causes elephantiasis of the lower extremities
- Microfilariae in the blood have a sheath and 2 terminal nuclei in the tail
Brugia malayi
Brugia malayi: Diagnostic and Infective
Diagnostic: microfilaria in blood
Infective: skin penetration of microfilariae by insect vector (Anopheles)