Cestodes Flashcards
- collectively called the______
- dorsoventrally flattened
- bilaterally symmetrical
Phylum Platyhelminthes
flatworms
Platyhelminths are covered by a membrane called
tegument
Platyhelminths are hermaphrodite except for
Schistosoma species
Characteristics of Class Cestoda
Taenia species (example)
Adult worms are seen in the intestine
Proglottids contain male and female parts
Eggs have 6 hooked embryos
World-wide distribution
nO digestive tract, no circulatory system
Ribbon-like body, flat
Middle (intermediate host is required)
Pseudophyllidea
2
● Diphyllobothrium latum
● Spirometra: S. erinacei ; S. mansoni ; S. ranarum
Cyclophyllidea
5
Taenia solium and Taenia saginata
Hymenolepis nana and Hymenolepis diminuta
Dipylidium caninum
Raillietina garrisoni
Echinococcus granulosus
CN
T soium
Pork tapeworm
CN
T saginata
Beef tapeworm
T multiceps
Coenurus Tapeworm
Echinococcus granulosus CN
Hydatid Tapeworm
Echinococcus multilocularis CN
The Multiloculate or
Alveolar Hydatid Tapeworm
Hymenolepis nana CN
Dwarf tapeworm
Hymenolepis diminuta CN
Rat tapeworm
Dipylidium caninum CN
Double-pored Tapeworm
Diphyllobothrium latum CN
Broad Fish Tapeworm
3 types of proglottid:
Immature
Mature
Gravid
– undeveloped sexual organ, nearest to the neck
immature
– fully mature sexual organ
mature
– contains fertilized egg, undergoes apolysis
gravid
Species of Class Cestoda
Species which require a vertebrate intermediate host
Taenia solium (pork tapeworm)
Taenia saginata (beef tapeworm)
Echinococcus granulosus (dogs, carnivores)
Species of Class Cestoda
Species which require an invertebrate intermediate host
▪ Dipylidium caninum (dog tapeworm, double-pored tapeworm)
▪ Hymenolepis diminuta (rat tapeworm)
▪ Raillietina garrisoni (Tribolium confusum)
Species of Class Cestoda
Species which may or may not require intermediate host
▪ Hymenolepis nana (dwarf tapeworm)
Species of Class Cestoda
Species which infect man in their larval stages
▪ Diphyllobothrium latum
▪ Echinococcus granulosus (hydatid worm)
▪ Echinococcus multilocularis
▪ Taenia solium
D latum
• Scolex is ____ shaped
• Scolex bears 2 slit-like grooves called_______ (1 on the dorsal surface and 1 on the ventral surface)
• Scolex has no ____ and ____
•_____ is thin and unsegmented and is much longer than the head
spoon-shaped or spatulate
bothria
no rostellum and no hooklets
Neck
Morphology
• 3,000 to 4,000 proglottids
• A mature segment is filled with male and female reproductive organs
• Terminal segments shrink and becomes empty as eggs are constantly discharged
• Dried up segments break off from the body in chains and are passed out in the host’s feces
• Uterus at the center of the segment appears in the form of a rosette
Diphyllobothrium latum
D latum
Uterus at the center of the segment appears in the form of a___
rosette
D latum ova
Bile stained or not?
Bile stained
Ova of _____
• Oval
• Bile stained
• Contains abundant granules and unsegmented ovum
• Inconspicuous operculum at one end and a small knob at the other end
• Does not float in saturated solutions of common salt
• A single egg gives rise to a single larva
• Not infective to man
• About 1 million released everyday
D latum
D latum
First stage larva
• Ciliated oncosphere that develops from egg in water
Coracidium
D latum
Second stage larva
• Spindle-like solid body with cephalic invagination
• Found inside the_____ (the first IH)
Procercoid
cyclops
D latum
Third stage larva
• Head is invaginated in the neck
• Found in the_____, the second IH
Plerocercoid
fresh water fish
Diphyllobothrium latum
• Definitive Host
• Habitat
• Man, dog, cat
Small intestine
D latum
• 1 st I.H.
• 2 nd I.H.
• Cyclops or Diaptomus
• Fresh water fish, pike, trout, salmon, perch
D latum
Mode of Infection
• Ingestion of imperfectly cooked infected fish or roe containing plerocercoid larvae
Diphyllobothrium latum
• Diagnosis
• Microscopic examination of feces for the characteristic operculated eggs
T solium
Color and length
whitish, creamy white, measures 3-5 meters
T saginata
Color and length
white and semitransparent, measures 5- 10 meters