GI cestodes and trematodes

Question 1

What are the three basic structures of the tapeworm?

Answer 1

1. Scolex - attachment 2. Neck - new segment generation 3. Body (strobila) - a long segmented structure

Question 2

What is the cause of beef tapeworm?

Answer 2

Taenia saginata

Question 3

What is the transmission for beef tapeworm (taenia saginata)?

Answer 3

Ingestion of encysted larvae in undercooked beef

Question 4

What is the diagnosis for taenia saginata?

Answer 4

Detection of proglottids or eggs in stool

Question 5

What is the cause of pork tapeworm?

Answer 5

Taenia solium

Question 6

What is the transmission for pork tapeworm (taenia solium)?

Answer 6

Ingestion of cysts from undercooked pork

Question 7

How does extra-intestinal disease (cysticercosis) result from pork tapeworm (taenia solium)?

Answer 7

Ingestion of embryonated eggs

Question 8

What are the properties of extra-intestinal pork tapeworm (taenia solium) infection?

Answer 8

1. Ingested eggs hatch in intestine and release infectious larvae which enter circulation to encyst in various locations 2. Space filling lesions cause localized inflammation 3. Neurocysticercosis - severe complication

Question 9

What is the cause of fish tapeworm?

Answer 9

Diphyllobothrium latum

Question 10

What is the transmission of fish tapeworm?

Answer 10

Ingestion of infectious larvae from undercooked fish

Question 11

What are the symptoms of fish tapeworm (diphyllobothrium latum)?

Answer 11

1. Transient nausea 2. Abdominal pain 3. Diarrhea 4. Macrocytic anemia - B12 deficiency (rare)

Question 12

What is the genus and species of dog tapeworm?

Answer 12

Echinococcus granulosus

Question 13

What are the properties of dog tapeworm infection?

Answer 13

1. Humans are intermediate host 2. Acquired through exposure to dog feces

Question 14

What is the pathogenesis of dog tapeworm?

Answer 14

1. Ingested eggs hatch in intestine 2. Larvae travel via blood stream to multiple body sites 3. Larvae create fluid filled cysts 4. Cysts must be surgically removed without breaking hyaline membrane

Question 15

What are properties of trematodes?

Answer 15

1. Humans are definitive host 2. Freshwater snails are intermediate hosts 3. Larval forms released from snails encyst on fish, shellfish, or vegetation - acquired via ingestion

Question 16

What are the features of fasciolopsis buski?

Answer 16

1. Transmission via freshwater aquatic plants 2. In small intestine cercariae excyst, attach to columnar epithelium and mature to egg laying adults (hermaphroditic)

Question 17

What is the diagnosis for fasciolopsis buski?

Answer 17

Detection of eggs in stool

Question 18

What are the two liver flukes?

Answer 18

1. Fasciola hepatica 2. Clonorchis sinensis

Question 19

Where is the liver fluke fasciola hepatica found?

Answer 19

Larval forms encyst on freshwater vegetation

Question 20

Where is the liver fluke clonorchis sinensis found?

Answer 20

Larval forms encyst in fish

Question 21

What are the features of fasciola hepatica infection?

Answer 21

1. Acquired through ingestion of aquatic plants 2. Migration through liver may induce tenderness and hepatomegaly 3. Fever and eosinophilia common 4. Biliary obstruction may occur (jaundice)

Question 22

What are the features of clonorchis sinensis infection?

Answer 22

1. Acquired through ingestion of undercooked fresh water fish with attached encysted cercariae 2. Light infections asymptomatic 3. Heavy infections - biliary obstruction, jaundice, hepatitis, hepatomegaly, gall stones 4. Endemic throughout Asia