Cestodes Flashcards
Taxonomy of Cestoda
General features of Cestoda
- no sexual dimorphism
- life cycle indirect with one intermediate host, except for Pseudophyllidea order
- adults live in small intestine
- eggs: contain embrionated egg L1 (6-hooked oncosphere) except for D.latum (zygote)
- infection: per os with L2 except for D.latum(L3)
- cestodes: infection caused by adults
- metacestodes:infection caused by larvae in intermediate hosts
Morphology of Cestodes
Morphology of Cestodes
Morphology of Cestodes
The only Cestode that develops with 2 intermediate hosts
D.latum
Becomes L1 in the environment, L2 in 1st intermediate host, L3 in 2nd intermediate host (infectious state for final host)
The only cestode producing unembridionated eggs
D.latum
Develop in environment to L1
L1 — ?
L2 — ?
L3 — ?
L1 = 6-hooked oncosphere
L2 =
L3 = (only in D.latum)
Diphyllobothrium latum. Name
Broad tapeworm, fish tapeworm
Mainly fishborn (fresh water) disease of human and animals
D.latum. Why is it called broad tapeworm?
Width of the segments are much bigger than height
Very characteristic!
D.latum. General characteristic
D.latum. Life cycle
Egg ->
coracidium (L1) ->
small copepod crustaceans (Cyclops spp.) where procercoid (L2) develops ->
freshwater fish hets infected by eating crustaceans and plerocercoid (L3) develops
D.latum. Prepatent period
2-6 weeks, in dogs 11-15 days
D.latum. Pathogenesis, clinical signs
Animals: usually asymptomatic
Man: long-lasting infection (decades), often subclinical or mild (e.g. abdominal discomfort, diarrhea, vomiting), uptake of vitamin B12 may lead to a macrocytic, megaloblastic anaemia in heavily infected individuals
D.latum. Diagnosis. Treatment
- FEC with sedimentation method
- examination of proglottids passed in the stool
Treatment: praziquantel