A 29-year-old Peruvian man presents with the incidental finding of a 10 by 8 by 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. Ten years ago, the patient emigrated to the United States 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. Over 1 billion people are infected with intestinal nematodes, and many millions are infected with filarial nematodes, flukes, and tapeworms. They are an even greater problem in domestic animals. Many drugs, which are 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 controlling 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 53–1 Drugs for the Treatment of Helminthic Infections.1 |Favorite Table|Download (.pdf)
Table 53–1 Drugs for the Treatment of Helminthic Infections.1
|Infecting Organism||Drug of Choice||Alternative Drugs|
|Ascaris lumbricoides (roundworm)||Albendazole or pyrantel pamoate or mebendazole||Ivermectin, piperazine|
|Trichuris trichiura (whipworm)||Mebendazole or albendazole||Ivermectin|
|Necator americanus (hookworm); Ancylostoma duodenale (hookworm)||Albendazole or mebendazole or pyrantel pamoate|
|Strongyloides stercoralis (threadworm)||Ivermectin||Albendazole or thiabendazole|
|Enterobius vermicularis (pinworm)||Mebendazole or pyrantel pamoate||Albendazole|
|Trichinella spiralis (trichinosis)||Mebendazole or albendazole; add corticosteroids for severe infection|
|Trichostrongylus species||Pyrantel pamoate or mebendazole||Albendazole|
|Cutaneous larva migrans (creeping eruption)||Albendazole or ivermectin||Thiabendazole (topical)|
|Visceral larva migrans||Albendazole||Mebendazole|
|Angiostrongylus cantonensis||Albendazole or mebendazole|
|Wuchereria bancrofti (filariasis); Brugia malayi (filariasis); tropical eosinophilia; Loa loa (loiasis)||Diethylcarbamazine||Ivermectin|
|Onchocerca volvulus (onchocerciasis)||Ivermectin|
|Dracunculus medinensis (guinea worm)||Metronidazole||Thiabendazole or mebendazole|
|Capillaria philippinensis (intestinal capillariasis)||Albendazole||Mebendazole|
|Schistosoma haematobium (bilharziasis)||Praziquantel||Metrifonate|
|Clonorchis sinensis (liver fluke); Opisthorchis species||Praziquantel||Albendazole|
|Paragonimus westermani (lung fluke)||Praziquantel||Bithionol|
|Fasciola hepatica (sheep liver fluke)||Bithionol or triclabendazole|
|Fasciolopsis buski (large intestinal fluke)||Praziquantel or niclosamide|
|Heterophyes heterophyes; Metagonimus yokogawai (small intestinal flukes)||Praziquantel or niclosamide|
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