Lesson 1 - Cestodes

Question 1

Intermediate host: Pigs. Transmitted by ingestion or larvae from undercooked pork or eggs in food and water contaminated by human feces

Answer 1

Taenia solium

Question 2

Scolex has four suckers and circle of hooks arranged around a rostellum

Answer 2

Taenia solium

Question 3

Adult tapeworm in intestines causes taeniasis, Cystericercus in brain causing cysticercosis

Answer 3

Taenia solium

Question 4

Diagnosed by Gravid Proglottids in stool (Larvae) or by Biopsy, CT scan (Eggs)

Answer 4

Taenia solium

Question 5

Treatment of choice: Praziquantel

Answer 5

Taenia solium / Taenia saginita / Diphyllobothrium latum

Question 6

Scolex has four suckers but no hooklets (no rostellum). Gravid proglottids has 15-25 uterine branches. Larvae (cysticerci) infective stage.

Answer 6

Taenia saginata

Question 7

Transmitted by ingestion of larvae (cysticerci) in undercooked beef. Adult tapeworm in intestine causes taeniasis.

Answer 7

Taenia saginata

Question 8

Symptoms include: Abdominal pain, weight loss, Pruritus ani, intestinal obstruction

Answer 8

Taenia saginata

Question 9

Difference between T. solium and T. saginata

Answer 9

T. saginata does not cause cysticercosis in humans.

T. solium has 5-10 uterines, while T. saginata hsa 15-25 uterine branches.

Question 10

Longest of the tapeworms. Scolex has two elongated sucking grooves for attachment, no hooks. First Intermediate Host: Copepods, Second IH: Fish.

Answer 10

Diphyllobothrium latum

Question 11

Transmitted by ingestion of plerocercoid larvae in undercooked fish.

Answer 11

Diphyllobothrium latum

Question 12

Adult tapeworm in intestines can cause diphyllobothriasis.

Answer 12

Diphyllobothrium latum

Question 13

Vitamin B12 deficiency in D. latum caused by preferential uptake of the vitamin by the worm

Answer 13

Megaloblastic anemia

Question 14

Unembryonated operculated eggs in stool

Answer 14

Diphyllobothrium latum

Question 15

Composed of a scolex and only three proglottids - one of the smallest tapeworms. Scolex has circle of hooks and four suckers.

Answer 15

Echinococcus granulosus

Question 16

Intermediate host are Sheep. Humans are accidental IH. Eggs ingested in food contaminated with dog feces (dogs are definitive host)

Answer 16

Echinococcus granulosus

Question 17

Larva causes unilocular hydatid cyst disease, especially in liver and lung.

Answer 17

Echinococcus granulosus

Question 18

Liver Cyst > hepatic dysfunction.
Pulmonary Cyst > erode into a bronchus > bloody sputum
Cerebral cysts > headache and focal neurological signs.
Rupture of cysts > anaphylactic shock

Answer 18

Echinococcus granulosus

Question 19

Treatment of Choice: Albendazole or surgical removal of cysts

Answer 19

Echinococcus granulosus

Question 20

Definitive Hosts: FOXES. IH: Rodents.

Transmitted by accidental ingestion of food contaminated with fox feces.

Larvae form multiloculated cysts (honeycomb vesicles).

Treatment: ALBENDAZOLE or surgical cyst removal

Answer 20

Echinococcus multilocularis

Question 21

Dwarf tapeworm (smallest cestode). Most frequently found tapeworm in developed countries.

Ingestion of cysticercoid larvae from infected RICE or FLOUR BEATLE.

Eggs are directly infectious for humans and can pass in the stool or reinfect the small intestine (autoinfection).

PRAZIQUANTEL treatment of choice.

Answer 21

Hymenolepsis nana

Question 22

Rat tapeworm.

Transmitted by ingestion of Rat Flea cysticercoid larvae. Accidental parasite.

Answer 22

Hymenolepsis diminuta

Question 23

Most common tapeworm of dogs and cats. Transmission is by ingestion of dog or cat fleas carrying cysticerci.

Diagnosis is by identification of “barrel-shaped” proglottids in stool.

NICLOSAMIDE drug of choice.

Answer 23

Dipylidium caninum