A. Prescribe praziquantel without further diagnostic testing
The key to the correct diagnosis in this patient is the histopathologic finding of granulomas containing schistosome eggs (Figure, black arrows) with lateral spines (Figure, blue arrow), consistent with Schistosoma mansoni, for which praziquantel is indicated (choice A). Although stool microscopy (choice B) is an appropriate first step, returning travelers often have low parasite burdens, so additional stool samples are low yield. The presence of schistosome eggs argues against tuberculosis as the cause of the granulomatous inflammation, so tuberculosis testing (choice C) and treatment (choice D) are not warranted.
Schistosomiasis is a parasitic infection caused by flukes. Schistosoma mansoni, found in Africa and the Arabian Peninsula, resides in mesenteric venules, leading to intestinal, hepatic, and/or pulmonary disease as a result of an immune response to migrating eggs that deposit in these organs.1 Infection is acquired through freshwater contact, from which larvae infect humans via skin penetration.2 Exposure to upper Nile River water is a risk factor for S mansoni acquisition. In one study, 17% of persons exposed to Ugandan Nile River water developed acute schistosomiasis.3