Class Cestoidea

Question 1

Diphyllobothrium latum

Answer 1

Fish or broad tapeworm, longest tapeworm found in man, from 3-10 m long with more than 3000 proglottids
Scolex has dorsal and ventral grooves (bothria) - no hooks or rostellum, scolex resembles 2 almond shaped leaves
Proglottids are wider than long
Rosette-shaped central uterus centrally filled with eggs
Parasites of humans and dogs, and inhabit the intestine
Causes: diphyllobothriasis, anemia, sparganosis

Question 2

Diphyllobothrium latum eggs

Answer 2

Similar to trematode eggs, has an operculum and possess a small knob at the opposite end
Ovoid shape
Contain embryos with 3 pairs of hooklets

Question 3

Taenia pisiformis

Answer 3

Dog tapeworm
Reaches up to 1m and 400 proglottids
Scolex has 4 suckers and a row of hooks
Proglottids are rectangular with unilateral genital pores
Causes taeniasis pisiformis in dogs and cats, inhabits small intestine

Question 4

Taenia pisiformis eggs

Answer 4

Mostly spherical
Oncosphere is surrounded by a thick inner wall (embryophore) that is riddled with numerous pores giving it a striated appearance

Question 5

Taenia solium

Answer 5

The most dangerous taenid in humans
Long, flat body around 100cm in length
Globular scolex with 4 suckers and a rostellum with 2 circular row of hooks (rostellum) that gives it a solar appearance

Question 6

Echinococcus granulosus

Answer 6

Smallest of all tapeworms, 3-9mm long
Comprised of a scolex, neck and strobila
1 immature, 1 mature, and 1 gravid proglottid
Scolex has 4 suckers and rostellum
Causes unilocular hyatid cyst disease in liver of dogs, pigs, and sheep

Question 7

Hymenolepis diminuta eggs

Answer 7

Large, spherical oncosphere with 6 hooks and a clear area between the oncosphere and shell wall
Infects rats and humans
Causes: hymenolepiasis diminuta in rats and mice and is located in intesting
Adult has no hooks

Question 8

Hymenolepis nana

Answer 8

Most common tapeworm
Scolex has 4 cup shaped suckers and 20-30 hooks
Proglottids are wider than long
Genital pores are unilateral, and there are 3 testes per segment
Causes: hymenolepiasis nana in rates and mice
Located in intestine

Question 9

Dipylidium caninum

Answer 9

Scolex has a retractable rostellum, armed with 4-7 rows of hooks and 4 suckers
Proglottids are double-pored: delicate, elongate, possess double the sexual organs
One genital pore on each side of the proglottid (key diagnostic)

Question 10

1. How can humans get diphyllobothrium latum? What is the vector or intermediate host?
2. How can humans become infected by hymenolepis nana?
3. How can humans become infected by dipylium caninum?

Answer 10

1. Through ingesting undercooked freshwater fish. Copepods
2. By ingesting eggs through water, food or hands that are contaminated or by ingesting an arthropod with cystercoid larvae
3. By ingesting a infected flea