MLT GlobeParasitology: Cestodes (tapeworms) – page 2
34 Parasitology MCQs on Cestodes (tapeworms) with answers and explanations.
The Casoni intradermal test, now obsolete and replaced by imaging plus serology (ELISA/immunoblot), was historically used for which infection?
Casoni's test used hydatid fluid antigen but had poor specificity; hydatid disease is now diagnosed by ultrasound/CT and serology. It was never used for the other infections.
Which finding confirms intestinal Taenia solium infection and distinguishes it from T. saginata?
Taenia eggs look alike, so species identification relies on gravid proglottids (T. solium 7–13 branches, T. saginata more than 12) or molecular tests. Tapeworms have no trophozoite or cercarial stage.
Which tapeworm can complete its whole life cycle in a single human host, without an intermediate host?
H. nana (dwarf tapeworm) eggs hatch in the villi, form cysticercoids and mature in the same host. The Taenia species and Echinococcus require intermediate hosts.
Among these helminths, which can reach the greatest length in the human intestine (often 4–10 m)?
The beef tapeworm T. saginata commonly grows to several metres. Ascaris, though the largest intestinal nematode, is only 20–35 cm long.
Beef containing which larval stage transmits Taenia saginata to humans?
Cysticercus bovis in cattle muscle develops into the adult worm. C. cellulosae is the T. solium larva, the coracidium belongs to Diphyllobothrium, and the miracidium to flukes.
Which helminth produces operculated eggs?
D. latum eggs have an operculum (lid) at one end, as do Fasciola, Paragonimus and Clonorchis. Schistosome eggs have spines but no operculum.
Human cysticercosis (larvae in brain or muscle) is acquired by swallowing:
Ingested T. solium eggs hatch and larvae spread to tissues to form cysticerci. Eating cysticerci in pork causes only intestinal taeniasis.
To identify a Taenia saginata proglottid, it is pressed between two slides after injecting its uterus with:
India ink fills the uterine branches; T. saginata has about 15 to 20 lateral branches per side, compared with 7 to 13 for T. solium.
Humans acquire all of the following from pigs or dogs except:
A. lumbricoides spreads person to person through eggs in fecally contaminated soil. Echinococcus comes from dogs, and T. solium and Trichinella from pigs.
A round egg about 35 µm with a thick radially striated shell containing a six-hooked oncosphere is seen. The correct report is:
Eggs of T. solium and T. saginata look identical, so they are reported as Taenia species. Species identification requires the scolex or gravid proglottids, or molecular testing.
Alveolar hydatid disease, which grows like an invasive tumour in the liver, is caused by:
E. multilocularis, with foxes as main definitive hosts, forms infiltrating multivesicular (alveolar) cysts; E. granulosus forms unilocular cysts.
Taenia eggs are seen in a stool sample. Why is the result reported as 'Taenia species' rather than naming the species?
The eggs of the two species cannot be told apart, so species identification needs a gravid proglottid (uterine branches) or the scolex.
Which tapeworm uses humans only rarely, as an accidental intermediate host with larvae (coenurus) in the brain or eye?
Coenurosis is a rare zoonosis from dog tapeworm T. multiceps eggs. T. saginata, T. solium and H. nana commonly infect humans.
A round egg about 75 µm with a six-hooked oncosphere is seen in stool. There are no polar filaments between the inner and outer membranes. It is most likely:
H. diminuta (rat tapeworm) eggs are larger than H. nana eggs and have polar thickenings without filaments. Taenia eggs have a thick striated shell.