MLT GlobeParasitology: Nematodes (roundworms) – page 4
66 Parasitology MCQs on Nematodes (roundworms) with answers and explanations.
Patients with Strongyloides stercoralis infection are at greatest risk of life-threatening hyperinfection when they receive:
Corticosteroids and other immunosuppression allow massive autoinfection and dissemination of larvae.
Cough, wheeze and eosinophilia with transient lung shadows (Loeffler's syndrome) occur in Ascaris infection when:
Ascaris larvae pass from the blood into the alveoli before being swallowed, causing pneumonitis with eosinophilia.
A soil-dwelling larva with a closed oesophagus and a POINTED tail penetrates the skin of a barefoot farmer. This infective stage belongs to:
Hookworm filariform (L3) larvae have a pointed tail and infect through skin. Strongyloides filariform larvae have a notched tail, and rhabditiform larvae are non-infective feeding stages.
Which nematode is described as ovoviviparous, its eggs hatching in the intestinal mucosa so larvae rather than eggs appear in stool?
Strongyloides eggs hatch almost immediately in the mucosa, so rhabditiform larvae are passed. Trichinella and Dracunculus are viviparous (release live larvae), while Enterobius is oviparous.
A sheathed microfilaria with a tail tip free of nuclei is found in blood collected at midnight. The species is most likely:
W. bancrofti is sheathed, nocturnally periodic, and has no nuclei in the tail tip. Brugia has two separate terminal nuclei; Loa loa has nuclei to the tail tip and daytime periodicity.
A night blood film from a patient from Malaysia shows sheathed microfilariae with two separate nuclei at the tip of the tail. The species is:
Brugia malayi microfilariae are sheathed and have two distinct terminal tail nuclei. W. bancrofti has no nuclei in the tail tip, and M. perstans is unsheathed.