E3- Helminths

Question 1

What is the causative agent of enterobiasis “pinworm disease”?

Answer 1

Enterobius vermicularis

Question 2

What is the lifecycle of Enterobius vermicularis?

Answer 2

• Eggs are deposited on perianal region and are then ingested
• Adults mature and gravid females migrate at night to the perianal region to deposit eggs
• Deposited eggs becomes infectious in 4-6 hours

Question 3

How does a Enterobius vermicularis infection present clinically?

Answer 3

Pruritis ani

Question 4

How is Enterobius vermicularis dx?

Answer 4

-Tape method to detect the presence of eggs on perianal skin

Question 5

What is the most effective way to minimize the spread of Enterobius vermicularis?

Answer 5

Handwashing

Question 6

Which 2 types of nematodes are transmitted via contaminated soil ingestion?

Answer 6

• Ascaris lumbricoides

- Trichuris trichiura

Question 7

What nematode is known as the “large intestinal roundworm”?

Answer 7

Ascaris lumbricoides

Question 8

What nematode is known as the “whipworm”?

Answer 8

Trichuris trichiura

Question 9

What is the lifecycle of Ascaris lumbricoides?

Answer 9

• Infective eggs are ingested
• Larvae travel through the bloodstream to the lungs
• Larvae travel to the mouth where they are swallowed
• Adult worms produce eggs that take weeks to become infectious

Question 10

What syndrome is a Ascaris lumbricoides infection associated with?

Answer 10

Pulmonary-Loeffler’s syndrome

Question 11

How is Ascaris lumbricoides dx?

Answer 11

Eggs in stool

Question 12

What is seen on the morphology of Trichuris trichiura?

Answer 12

• Whiptail

- Egg capsules

Question 13

What is the lifecycle of Trichuris trichiura?

Answer 13

• Infective (embryonated) eggs are ingested
• Larvae are released and mature into adults
• Adults release eggs

Question 14

How does a Trichuris trichiura infection present clinically?

Answer 14

• Frequent painful passage of stool
• Rectal prolapse can occur
• Children may suffer growth retardation and anemia

Question 15

How is Trichuris trichiura dx?

Answer 15

Presence of eggs in stool

Question 16

Which worms are considered hookworms?

Answer 16

• Necator americanus

- Ancylostoma duodenale

Question 17

What is the pathophysiology of Necator americanus and

Ancylostoma duodenale?

Answer 17

Feed on blood from intestinal mucosa

Question 18

How are Necator americanus and

Ancylostoma duodenale transmitted?

Answer 18

Infective stage larvae (filariform) penetrate skin

Question 19

How do Necator americanus and

Ancylostoma duodenale infections present clinically?

Answer 19

• Blood-filled, pruritic lesions at the site of larval penetration “ground itch”
• Anemia

Question 20

How are Necator americanus and

Ancylostoma duodenale dx?

Answer 20

Presence of eggs in stool sample

Question 21

What worm is known as “threadworms”?

Answer 21

Strongyloides stercoralis

Question 22

What are the two multiplication cycles of Strongyloides stercoralis?

Answer 22

In host (parasitic) or in soil (free living)

Question 23

How is Strongyloides stercoralis transmitted?

Answer 23

Infective larvae in soil penetrate the skin

Question 24

How does Strongyloides stercoralis present clinically?

Answer 24

• Diarrhea, pain constipation, malabsorptioon

- Autoinfection can occur leading to chronic infection

Question 25

A Strongyloides stercoralis infection can be life threatening in pts with what?

Answer 25

A defect in cell mediated immunity

Question 26

How is Strongyloides stercoralis dx?

Answer 26

-Presence of larvae in stool sample

Question 27

What is the morphology of trematodes (flukes)?

Answer 27

- Flattened, leaflike body - Presence of suckers - Hermaphroditic

Question 28

What type of worms have 2 intermediate hosts and 1 definitive host?

Answer 28

Trematodes (flukes)

Question 29

What type of worm is commonly found in pork?

Answer 29

Taenia solium

Question 30

What type of worm is commonly found in beef?

Answer 30

Taenia saginata

Question 31

What type of worm are Taenia solium and Taenia saginata?

Answer 31

Tapeworms

Question 32

What structure is unique to tapeworms (Taenia solium and Taenia saginata)?

Answer 32

Scolex (head structure)

Question 33

Are eggs released in the proglottids of Taenia solium and Taenia saginata infectious or non-infectious?

Answer 33

Immediately infectious

Question 34

What are the larvae of Taenia solium and Taenia saginata called?

Answer 34

Cysticeri

Question 35

What is the lifecycle of Taenia solium and Taenia saginata?

Answer 35

- Infective eggs ingested by cattle or pigs - *Cysticerci (larvae)* develop in muscle - Poorly cooked meat ingested by a human releases the cysticercus - Proglottids (segments) released in the feces contain infectious eggs

Question 36

What can develop in Taenia solium infections if infective eggs are ingested?

Answer 36

Cysticercosis | -Typically asymptomatic, but serious sequlae can occur depending on infected site

Question 37

How are Taenia solium and Taenia saginata dx? (3)

Answer 37

- Presence of eggs or proglottids in stool sample - Lesions demonstrated by CT scans - Definitive = histology

Question 38

What type of worm can become very long and contain thousands of proglottids?

Answer 38

Diphyllobothrium latum

Question 39

What is the difference between the proglottids in Taenia solium/Taenia saginata and Diphyllobothrium latum?

Answer 39

Diphyllobothrium latum eggs are released singly, not in proglottids

Question 40

Where is Diphyllobothrium latum geographically predominant?

Answer 40

The great lakes region and Alaska

Question 41

What is the lifecycle of Diphyllobothrium latum?

Answer 41

- Infective larvae found in muscles of fish - Poorly cooked fish ingested by a human release the larvae - Adult worm develops and releases eggs in the feces - Eggs hatch in fresh water and are ingested by crustaceans - Crustaceans ingested by a small fish

Question 42

What does the Diphyllobothrium latum worm compete for in humans? What other infection did we talk about that can cause this?

Answer 42

Vitamin B12 | Giardia lamblia

Question 43

How is Diphyllobothrium latum dx? (3)

Answer 43

- Presence of eggs in stool - ID of adult worm - Anemia