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
Spirometrosis and sparganosis
Caused by plerocercoid of Spirometra spp
The old name of plerocercoid of Spirometra
…..
Monieziosis, stilesiosis, thysanosomosis
Tapeworm disease of ruminants
Caused by:
Moniezia expansa (dominant, cosmopolitan) up to 6m, width 15 mm
Moniezia benedeni (less common) up to 4 m, width 25 mm in large animals
Thysaniezia giardi
Avitellina centripuncuta
Stilesia globipuncata
Morphology of tapeworms …
Life cycle:
Tape worms of carnivores
Echinococcus granulosus - dwarf tapeworm of dogs
Echinococcus multilocularis - dwarf tapeworm of foxes
Dipylidium caninum - cucumber-like tapeworm
Taenia pisiformis (0.3-1.5m)
T. hydatigena (0.5-2.5 m)
T. ( syn. Multiceps) multiceps (0.4-1 m)
T. krabbei (syn. T. cervi) (2-2.5 m)
T. ovis (0.5-1.4 m)
T. crassiceps (0.1-0.2 m) foxes
T. taeniaeformis cat tapeworm (0.2-0.6 m) cat, lynx, red foxes
T. serialis (0.2-0.8 m)
Mesocestoides spp. (M. litteratus, M. lineatus) (0.3-2.5 m)
What egg type of tapeworms of carnivores is called?
Taenia type egg
- 30-40 micrometers
- oval
- inside 6-hooked oncosphere (L1)
Life cycle of tapeworms of carnivores
indirect with 1 intermediate host
Infective stage: L2
Echinococcus granulosus
- adult 3-6 mm long
- 3 (2-6) segments
- 4 suckers and rostellum
- lives up to 1 year in anterior half of the small intestine
- taenia-type eggs
Echinococcus multilocularis
The dangerous fox tapeworm
Hosts: red foxes, dogs, cats
- adults 2-4 mm long
- 5 segments
- eggs survive 2-3 months in summer, about 8 months in cooler seasons
- 20.000 eggs/segment