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A 29-year-old Peruvian man presents with the incidental finding of a 10 × 8 × 8-cm liver cyst on an abdominal computed tomography (CT) scan. The patient had noted 2 days of abdominal pain and fever, and his clinical evaluation and CT scan were consistent with appendicitis. His clinical findings resolved after laparoscopic appendectomy. The patient immigrated to the USA 10 years ago from a rural area of Peru where his family trades in sheepskins. His father and sister have undergone resection of abdominal masses, but details of their diagnoses are unavailable. What is your differential diagnosis? What are your diagnostic and therapeutic plans?


Helminths (worms) are multicellular organisms that infect very large numbers of humans and cause a broad range of diseases. More than 1 billion people are infected with intestinal nematodes, and many millions are infected with filarial nematodes, flukes, and tapeworms in other organs. Many drugs, directed against a number of different targets, are available to treat helminthic infections. In many cases, especially in the developing world, the goal is control of infection, with elimination of most parasites, alleviating disease symptoms, and decreasing the transmission of infection. In other cases, complete elimination of parasites is the goal of therapy, although this goal can be challenging with certain helminthic infections, because of both limited efficacy of drugs and frequent reinfection after therapy in endemic areas.

Table 53–1 lists the major helminthic infections and provides a guide to the drug of choice and alternative drugs for each infection. In the text that follows, these drugs are arranged alphabetically. In general, parasites should be identified before treatment is started.

TABLE 53–11Drugs for the treatment of helminthic infections.1

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