Snapshot A 30-year-old man presents to the urgent care clinic for fevers, a skin rash, and a cough. He reports that he had traveled to Japan last week. He had walked around the coastline barefoot and ate many meals of raw fish. He also reports having some unexpected weight loss and loss of appetite. On exam, he has edematous pink plaques consistent with urticaria. Basic laboratory evaluation is largely normal with the exception of elevated eosinophil levels. He is suspected of having Katayama fever and a stool exam is ordered, revealing eggs with a lateral spine. He is started on praziquantel. (Schistosoma japonicum infection) Introduction Drugs pyrantel pamoate ivermectin mebendazole praziquantel diethylcarbamazine niridazole Clinical use helminths cestodes (tapeworms) trematodes (flukes) nematodes (roundworms) Anti-Helminth Medications Drug Mechanism of Action Adverse Effects Helminth Pyrantel pamoate Neuromuscular blocking agent, causing depolarization Gastrointestinal upset Headaches Nematodes: Enterobius Ancylostoma Necator Ivermectin Binds to glutamate-gated chloride channels, causing hyperpolarization Skin pruritus Nematodes: Onchocerca (Rivermectin) Strongyloides Bendazole Inhibits tubulin polymerization, interfering with microtubule formation Gastrointestinal upset Stevens-Johnson syndrome Mebendazole Nematodes: Enterobius Ascaris Toxocara Trichuris Trichinella Strongyloides Ancylostoma Necator Albendazole: cestodes Taenia Echinococcus Praziquantel Unknown, may interfere with cell membrane permeability and cause paralysis in the helminth Gastrointestinal upset Dizziness Cestodes: Taenia Diphyllobothrium Trematodes: Schistosoma Clonorchis Paragonimus Diethylcarbamazine Inhibits arachidonic acid metabolism, making the helminth more susceptible to the host's innate immune system Skin pruritus Facial swelling Headaches Nematodes: Wucheria Loa loa Niridazole Inhibits oogenesis and spermatogenesis Central nervous system toxicity Nematode Dracunculus