MLT GlobeParasitology: Trematodes (flukes) – page 2
25 Parasitology MCQs on Trematodes (flukes) with answers and explanations.
For the best recovery of Schistosoma haematobium eggs, urine should be collected:
Egg excretion in urine peaks between about 10:00 and 14:00, and the terminal portion contains the most eggs. Urine is then sedimented or filtered.
A small (about 30 µm) operculated egg with prominent 'shoulders' around the operculum and a small knob at the other end is typical of:
The Chinese liver fluke egg is small with a shouldered operculum. Fasciola eggs are very large (130–150 µm) with an indistinct operculum.
A stool from a patient from the Philippines shows rounded eggs about 80 × 60 µm with a tiny, barely visible lateral knob. The most likely species is:
S. japonicum eggs are rounder and smaller than other schistosome eggs, with a minute lateral knob, and occur in East Asia. S. mansoni has a large lateral spine and S. haematobium a terminal spine.
How do schistosomes differ from most other human flukes?
Schistosomes are dioecious, with the female held in the male's gynaecophoric canal; most other trematodes are hermaphrodites.
A large yellow-brown egg (about 140 × 80 µm) with an indistinct operculum is found in a patient who eats watercress. The parasite is most likely:
Fasciola eggs are among the largest helminth eggs, with a small indistinct operculum; infection follows eating contaminated aquatic plants. Fasciolopsis eggs look the same, so history is important.