Nematodes - Intestinal

Question 1

What are the Intestinal Nematodes? (6)

Answer 1

• Enterobius Vermicularis
• Trichuris trichiura
• Ascaris lumbricoides
• Necator americanus
• Ancylostoma duodenale
• Strongyloides stercoralis

Question 2

Enterobius Vermicularis:

-AKA

Answer 2

PInworm (oxyuriasis)

Question 3

Enterobius Vermicularis - Adult Morphology:

• Sex
• Shape
• Cross-section

Answer 3

Female

• Slightly bent/pointed (pinlike) tail
• Lateral alae (characteristic)

Question 4

Enterobius Vermicularis - Egg:
-Morphology (3)

*Identification

Answer 4

• 30-50 um
• Thin-walled
• 1 flattened side

*Cellophane tape test (NOT seen in stool)

Question 5

Enterobius Vermicularis:

• Transmission
• Symptoms
• Complication

Answer 5

• Ingestions of Eggs
• Anal pruritis, vaginitis, and/or enuresis (urinary incontinence)
• Appendicitis

Question 6

Enterobius Vermicularis:

-Adult female life

Answer 6

• Inhabit Cecum/Appendix

- Lay eggs in perianal region (nocturnally)

Question 7

What is the most common helminthic infection in American Children?

Answer 7

Enterobius vermicularis (pinworm)

Question 8

Trichuris trichiura:

-AKA

Answer 8

Whipworm

Question 9

Trichuris trichiura - Adult worm:

-Morphology (2)

Answer 9

• up to 5 cm

- Whiplike anterior end

Question 10

Trichuris trichiura - Egg:

-Morphology (4)

Answer 10

• 50x25 um
• Brownish Thick shells
• Barrel-Shaped
• Bilateral Polar Plugs

Question 11

Trichuris trichiura:

• Infection sxs
• Complication

Answer 11

• Asymptomatic to Dysentery-like

- Rectal prolapse in young children

Question 12

Ascaris lumbricoides:

-AKA

Answer 12

Roundworm

Question 13

Ascaris lumbricoides - Adult worm:

-Morphology

Answer 13

Largest nematode

-up to 35 cm

Question 14

Ascaris lumbricoides - Eggs:

-Morphology (4)

Answer 14

• 60 um
• Bile-stained
• Thick Hyaline shell
• Rough mammillated surface

Question 15

Ascaris lumbricoides - Life cycle in humans. (6)

Answer 15

1. Ingestion of eggs
2. Hatch to produce larvae
3. Larvae enter bloodstream
4. Lungs (Loeffler syndrome)
5. Cough, swallow
6. Adults infect Duodenum

Question 16

Ascaris lumbricoides:

• Symptoms
• Complications

Answer 16

Asymptomatic

• Bowel obstruction
• Cholangitis
• Appendicitis

Question 17

Necator americanus and Ancylostoma duodenale:

-AKA

Answer 17

Hookworms

Question 18

Necator americanus and Ancylostoma duodenale:

• Adult size
• Differing features (Mouth Parts)

Answer 18

-1 cm in length

Necator americanus:
-Cutting plates

Ancylostoma duodenale:
-“Teeth”

Question 19

Necator americanus and Ancylostoma duodenale:

-Eggs (2)

Answer 19

• Thin, translucent wall
• Morula-like cluster of spherical embryos

*Indistinguishable

Question 20

Where is N. americanus found?

Answer 20

Southeastern US

*A. duodenale NOT found in US

Question 21

Necator americanus and Ancylostoma duodenale:

-Life Cycle (3)

Answer 21

• Larvae penetrate skin (feet)
• Lungs (cough/swallow)
• Adults infest Small bowel

Question 22

Necator americanus and Ancylostoma duodenale:

-Symptoms (3)

Answer 22

• Pruritic lesion (ground itch)
• Loeffler syndrome
• Iron deficiency anemia

Question 23

Strongyloides stercoralis:

-AKA

Answer 23

Thread worm

Question 24

Strongyloides stercoralis - Adult worm:

• Sex
• Size
• Location

Answer 24

• Female
• 3 mm
• Intestinal crypts

Question 25

Strongyloides stercoralis egg is identical to what other nematode? -Stool (+/-)

Answer 25

``` Hookworm egg (N. americanus/A. duodenale) -Not typically found in stool ```

Question 26

Strongyloides stercoralis - Eggs hatch in ____ and feces contain _____.

Answer 26

- Hatch in bowel | - Rhabditoid larvae in stool

Question 27

How do you distinguish Strongyloides stercoralis larvae from hookworm larvae? (2)

Answer 27

Strongyloides stercoralis: - Shorter buccal groove - Prominent genital primordium

Question 28

Where is Strongyloides stercoralis typically found? (3)

Answer 28

- Southeastern US - Tropics - Subtropics

Question 29

Strongyloides stercoralis: | -Life cycle (4)

Answer 29

Similar to hookworms. 1. Penetrate skin 2. Migrate through lungs 3. Cough/Swallow 4. Duodenal infection

Question 30

Strongyloides stercoralis: | -Complication in malnourished host

Answer 30

Autoinfection | -larvae may penetrate bowel wall, circulating through the lungs and reinfecting the duodenum

Question 31

Strongyloides stercoralis: | -Complication in immunocompromised host

Answer 31

Autoinfection/Hyperinfection | -Disseminated larvae-Deadly