2. Nematodes Flashcards
Most common intestinal helminth infection worldwide
A. lumbricoides
Diagnostic stage (DS) of A. lumbricoides
Ova in stool
Infective stage (IS) of A. lumbricoides
Ova
Pinworm
Enterobius vermicularis
Specimen of choice for E. vermicularis
Scotch tape preparation
IS of E. vermicularis
Ova
DS of E. vermicularis
Ova
Larva
E. vermicularis ova is infective within
4-6 hours
Mechanism of retroinfection by E. vermicularis
Ova hatch in anus but migrate back into colon to reproduce
Mechanism of autoinfection by E. vermicularis
Infective ova are ingested, hand to mouth
E. vermicularis ova may cary _______________
Dientamoeba fragilis
New world hookworm
Necator americanus
DS of N. americanus
Ova
IS of N. americanus
Third-stage filariform larvae
Roundworm
Ascaris lumbricoides