Chapter 56: Nematodes

Chapter 56: Nematodes

SELF-ASSESSMENT QUESTIONS

1. You are a volunteer with Doctors Without Borders in sub-

Saharan Africa. In certain villages, you detect anemia in a significant

number of children. This is most likely due to infection with

which one of the following?

(A) Ancylostoma duodenale

(B) Ascaris lumbricoides

(C) Enterobius vermicularis

(D) Trichinella spiralis

(E) Wuchereria bancrofti

1. In the same villages as described in Question 1, you observe that

some people are eating unwashed raw vegetables. Which one of

the following organisms is most likely to cause infection in these

people?

(A) Ancylostoma duodenale

(B) Ascaris lumbricoides

(C) Enterobius vermicularis

(D) Trichinella spiralis

(E) Wuchereria bancrofti

1. Which one of the following nematodes is transmitted by a filariform

larva penetrating the skin?

(A) Anisakis simplex

(B) Onchocerca volvulus

(C) Strongyloides stercoralis

(D) Toxocara canis

(E) Trichuris trichiura

1. One of the most important public health measures in the United

States in the twentieth century was recommending that children

in rural areas wear shoes. This effort was designed to prevent

infection through the feet with which one of the following

organisms?

(A) Ascaris lumbricoides

(B) Enterobius vermicularis

(C) Necator americanus

(D) Onchocerca volvulus

(E) Trichuris trichiura

1. The larvae of certain nematodes migrate through the lung and

cause pneumonitis characterized by cough or wheezing. Infection

by which one of the following nematodes is most likely to

cause this clinical picture?

(A) Anisakis simplex

(B) Ascaris lumbricoides

(C) Enterobius vermicularis

(D) Trichinella spiralis

(E) Trichuris trichiura

1. Of the following drugs, which one is the MOST effective in nematode

infections?

(A) Albendazole

(B) Chloroquine

(C) Praziquantel

(D) Primaquine

(E) Stibogluconate

1. Your patient is a 60-year-old man with abdominal pain, vomiting,

and weight loss for the past 2 months. He has a history of

asthma that requires 20 mg of prednisone daily to control. He

lived most of his life in Cuba, moved to Spain 10 years ago, and

has lived in this country for 1 year. Abdominal exam is normal,

and radiographic studies are unrevealing. His white blood cell

count is 10,900 with 16% eosinophils. Examination of the stool

reveals rhabditiform larvae. Of the following, which organism is

the MOST likely cause?

(A) Ascaris lumbricoides

(B) Onchocerca volvulus

(C) Strongyloides stercoralis

(D) Toxocara canis

(E) Trichinella spiralis

1. Regarding the patient in Question 7, which one of the following

is the best drug to treat the infection?

(A) Ivermectin

(B) Metronidazole

(C) Nifurtimox

(D) Pentamidine

(E) Praziquantel

1. Your patient is a 40-year-old man with fever, myalgia, and facial

swelling. White blood cell count was 14,400 with 24% eosinophils.

Additional history reveals that he shot a bear in Canada

and ate some of it about 6 weeks ago. He emphasized that he likes

his meat rare. A muscle biopsy was performed, and a H&E stain

of the tissue showed coiled larvae within skeletal muscle. Of the

following, which one is the most likely cause?

(A) Ancylostoma caninum

(B) Anisakis simplex

(C) Necator americanus

(D) Trichinella spiralis

(E) Wuchereria bancrofti

1. Your patient is a 35-year-old woman with severe upper abdominal

pain for the past hour. There is no nausea, vomiting, or diarrhea.

You suspect she may have cholecystitis, pancreatitis, or a

perforated viscus but first ask her if she has ingested raw fish

recently. She says yes, and tells you that she had sashimi the night

before last. Endoscopy reveals a larva in the gastric mucosa. Of

the following, which one is the most likely cause?

(A) Ancylostoma caninum

(B) Ancylostoma duodenale

(C) Anisakis simplex

(D) Toxocara canis

(E) Trichuris trichiura

1. Your patient is a 5-year-old boy who complains of perianal itching,

especially at night. A “Scotch tape” preparation reveals the

eggs of Enterobius in the microscope. Which one of the following

is the best drug to treat his pinworm infection?

(A) Ivermectin

(B) Mebendazole

(C) Pentamidine

(D) Praziquantel

(E) Pyrimethamine and sulfadiazine

ANSWERS

1. (A)
2. (B)
3. (C)
4. (C)
5. (B)
6. (A)
7. (C)
8. (A)
9. (D)
10. (C)
11. (B)