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Chapter 37: Chemotherapy of Helminth Infections

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A 32-year-old man is seen because of megaloblastic anemia of unknown origin. After considerable workup, he is discovered to have an intestinal fish tapeworm, Diphyllobothrium latum. Treatment with praziquantel eliminates the worm and cures his anemia. The cause of the anemia in patients with Diphyllobothrium latum infection is

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a. iron deficiency.

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b. vitamin B12 deficiency.

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c. folic acid deficiency.

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d. vitamin E deficiency.

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e. intestinal blood loss.

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Answer is b. The cause of anemia in Diphyllobothrium latum infections is a deficiency of vitamin B12, which is taken up by the parasite.

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A 23-year-old woman returns from several years in sub-Saharan Africa. She has lymphadenitis and decreasing eyesight. She is diagnosed with onchocerciasis. Both ivermectin and diethylcarbamazine (DEC) are known to be effective against Onchocerca volvulus. Why is ivermectin chosen over DEC in the treatment of onchocerciasis?

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a. DEC may worsen ocular lesions.

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b. DEC is not absorbed from the GI tract.

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c. Ivermectin may be given by intramuscular injection.

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d. Resistance to DEC is common.

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e. DEC is contraindicated in women.

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Answer is a. DEC is contraindicated for the treatment of onchocerciasis because it causes severe reactions related to microfilarial destruction, including worsening ocular lesions. Such reactions are far less severe in response to ivermectin.

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A 4-year-old boy is brought into your office because of a possible pinworm infection. Examination of the anal area confirms the diagnosis of Enterobius (pinworm). Which of the following drugs would you recommend to treat this infection?

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a. Ivermectin

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b. DEC

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c. Praziquantel

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d. Pyrantel pamoate

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e. Metrifonate

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Answer is d. In the United States, pyrantel pamoate is sold as an over-the-counter pinworm treatment. High cure rates are achieved after a single oral dose, although it is wise to repeat the treatment after an interval of 2 weeks. If the child is in a day-care center, it may be prudent to recommend that other children in the center seek consultation with a physician and treatment if necessary. An alternate choice would be mebendazole.

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A 25-year-old woman immigrant from Guatemala is ...

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