Chapter 55: Trematodes

Chapter 55: Trematodes

SELF-ASSESSMENT QUESTIONS

1. Regarding schistosomes, which one of the following statements is

the most accurate?

(A) The visual appearance of male and female schistosomes is the

same.

(B) Humans are infected by schistosomes when cercariae penetrate

the skin.

(C) Infection of freshwater fish is a required part of the life cycle of

schistosomes.

(D) The pathology of schistosomiasis is principally caused by the

cercariae entering hepatocytes and killing them.

(E) Infection by nonhuman schistosomes can cause meningitis in

people who swim in certain lakes in the United States.

1. Regarding Schistosoma mansoni, which one of the following statements

is the most accurate?

(A) The main site of S. mansoni in the human body is the mesenteric

venules.

(B) Schistosomiasis caused by S. mansoni has been eradicated from

the Western hemisphere.

(C) The laboratory diagnosis of S. mansoni depends on seeing eggs

with a terminal spine in the stool.

(D) Adult schistosomes are passed in the stool, and it is obligatory

that they be ingested by freshwater snails to continue the life

cycle.

(E) Swimmer’s itch occurs when S. mansoni eggs spread from the

liver to the skin, where they induce a histamine-mediated

immediate (type 1) hypersensitivity reaction.

1. Which one of the following is the drug of choice for infections

with S. mansoni and S. haematobium?

(A) Albendazole

(B) Metronidazole

(C) Nifurtimox

(D) Praziquantel

(E) Stibogluconate

1. Your patient is a 30-year-old man with low-grade perineal pain

for several weeks who had an episode of painful ejaculation and

postcoital hematuria yesterday. He is in a long-standing monogamous

relationship. He has traveled extensively throughout the

world during the past 10 years. Urinalysis and urine culture were

negative. Cytologic examination of cells in the urine revealed no

tumor cells. Cystoscopy revealed several polypoid lesions, and a

biopsy of a lesion was taken. The tissue was examined in the light

microscope, and eggs with a terminal spine were seen. Of the following,

which one is the MOST likely cause?

(A) Clonorchis sinensis

(B) Paragonimus westermani

(C) Schistosoma haematobium

(D) Schistosoma japonicum

(E) Schistosoma mansoni

ANSWERS

1. (B)
2. (A)
3. (D)
4. (C)