Cestodes

Question 1

tapeworms

Answer 1

cestodes

Question 2

morphology of cestodes

Answer 2

• Flattened, ribbon-like
• Body made of chain (strobila) of segments (proglottids), each containing it’s own set of internal organs (including male and female genital systems)

Note – they do NOT have a gastrointestinal tract!!!
- absorb food through entire SA

• Head (scolex) equipped with attachment organs (via suction)
  > no muscles connecting segments = floppy; so scolex need to have efficient organs to keep attached to bowel (SUCTION)
• No body cavity

Question 3

two main groups of cestodes that infect humans

Answer 3

Pseudophyllid cestodes (genus Diphyllobothrium only)
Cyclophyllid cestodes (all other tapeworms)

Question 4

T or F. Adult cestodes infect vertebrates and larvae infect both vertebrates and invertebrates

Answer 4

T!

Question 5

Pseudophyllid cestodes

Answer 5

• D. latum = fish tapeworm
  > renamed Dibothriocephalus latus
• Spirometra sp. = sparganosis

> elongated scolex with sucking grooves bothria (instead of sucking discs)
flat-ribbon like worms
minimum of 3 hosts

Question 6

Cyclophyllid cestodes

Answer 6

Tenia solium
Tenia saginata
Echinococcus granulosus
Echinococcus multilocularis
Dipylidium caninum

Question 7

morphology of Cyclophyllid cestodes

Answer 7

Adult Body = 3 mm to 25 m long

Head (scolex) with round suckers and (for some - hooks or suckers (on rostellum)

Immature forms
- Egg
- Larva (cysticercus = contains one larval form, hydatid = contains huge larval forms growing freely into lumen cyst)

Life cycle generally requires 2 hosts
(sometimes definitive host serves as intermediate host)

Question 8

organs of attachment

Answer 8

round suckers
- keeps long floppy tapeworms suctioned onto internal surface of gut

Question 9

characteristic for tapeworm eggs

Answer 9

little embryonic hooklets

Question 10

T or F. T. solium does not have rostellum

Answer 10

F! T. saginata doesn’t; just four suckers

Question 11

gravid segments to differentiate between T. solium and T. saginata

Answer 11

T. saginata = uterine branches ; 15-30 branches on each side

T. solium = 7-13 branches

Question 12

Cyclophyllid tapeworms location

Answer 12

small intestine (adult worms)
liver, brain, muscle, etc. (larvae)

Question 13

distribution of Cyclophyllid tapeworms

Answer 13

worldwide

Question 14

ingestion of eggs tapeworm

Answer 14

(through contaminated food/water usually)
larval form of disease of E. granulosus and T. solium