Intestinal and Tissue Cestodes

Question 1

Life cycle: larvae-intestine-adults
Route of infection: ingestion infected raw, poorly cooked or pickled freshwater fish
Geography: freshwater lakes
Specimen source: stool sample
Morphology: adults; scolex, strobila. eggs; percolated, 58-75 mcm
Lab tests: wet prep, formalin ethyl-acetate concentration of stool
Pathology: diarrhea, obstruction, B12 deficiency, macrycytic anemia

Answer 1

Diphyllobothrium latum

Question 2

Life cycle: cysticerci-intestine-adults
Route of infection: ingestion infected raw or poorly cooked pork/ cysticercosis - ingestion of egg
Geography: worldwide. Hispanic population - US Southwest
Specimen source: stool sample
Morphology: adults; scolex, strobila, gravid proglottids=7-13 uterine branches. eggs; thick, striated shell, 6 hooked embryo, 31-43 mcm.
Lab tests: wet prep, formalin ethyl-acetate conc. of stool; ELISA - coproantigen test
Pathology: diarrhea, weight loss; cysticercosis: ingestion of egg - pseudo-brain tumor, Immunoblot test, CDC

Answer 2

Taenia solium

Question 3

Life cycle: cysticerci-intestine-adults
Route of infection: ingestion infected raw or poorly cooked beef
Geography: worldwide
Specimen source: stool sample
Morphology: adults; scolex, strobila-proglottids; gravid proglottids=15-20 uterine branches. eggs; like Tania solium, 31-43 mcm
Lab test: wet prep, formalin ethyl-acetate conc. of stool
Pathology: diarrhea, weight loss, appendicitis.

Answer 3

Taenia saginata

Question 4

Life cycle: eggs-larvae-adults
Route of infection: ingestion of eggs
Geography: worldwide
Specimen source: wet prep conc. stool
Morphology: adults; 25-40 mm, long, scolex-4 sucker, short restellum with hooks, proglottids-broad. eggs; 30-47 mcm long, oval to round, polar filaments, polar thickening
Lab test: wet prep conc. stool
Pathology: asymptomatic, dizziness, nausea, auto infection possible

Answer 4

Hymenolepis nana - Dwarf tapeworm

Question 5

Life cycle: cysticercoids-intestine-adults
Route of infection: ingestion infected arthropods (various beetles, larval fleas)
Geography: worldwide
Specimen source: stool sample
Morphology: adults; 20-60 cm. long. eggs; like H. nana, except to no polar filaments, 70-85/60-79 mcm.
Lab test: wet prep conc. stool
Pathology: few symptoms - nausea, anorexia, diarrhea, headache

Answer 5

Hymenolepis diminuta

Question 6

Life cycle: cysticercoid larva-intestine-adult
Route of infection: ingestion of infected dog or cat flea
Geography: worldwide
Specimen source: stool sample
Morphology: adults; 10-70 cm. long, scolex-4 suckers, proglottids-barrel shaped. eggs; 25-40 mcm often in egg packet.
Lab tests: wet prep conc. stool
Pathology: indigestion, appetite loss

Answer 6

Dipylidium caninum

Question 7

Life cycle: eggs-hydatid cysts, lung, liver
Route of infection: ingestion eggs from dogs. Humans are accidental intermediate hosts
Geography: Australia, New Zealand, Alaska, Canada, Continental U.S.
Specimen source: stool sample
Lab test: history, x-rays or scans. variety of immunoassay tests-Enzyme-linked immunoelectrotransfer blot (ELIB), ELISA, Arc-5 double diffusion assay (DD5)
Pathology: abdomen discomfort, anaphylactic rxn

Answer 7

Echinocactus granulosus - Hydatid disease

Question 8

Life cycle: eggs-hydatid cysts-liver
Route of infection: ingestion eggs from dogs, foxes, wolves, and cats
Geography: Alaska, former USSR, Japan, China
Specimen source: stool sample
Lab test: variety immunoassays, PCR-specimen obtained from fine needle aspiration (FNA)
Pathology: may resemble a slow growing carcinoma, hepatomegaly, splenomegaly

Answer 8

Echinocactus multicularis - Alveolar Hydatid disease