Positive fecal occult blood test as a diagnostic cue for Schistosoma mansoni infection in a developed country

The rise in eco-tourism and travel off the beaten track have increased numbers of tourists with schistosomiasis which is seldom seen in developed countries, although this disease is considered a neglected tropical disease especially in poor communities. A Guinean male living in Japan was seen complaining of severe constipation. He was positive for fecal occult blood (FOB) and underwent colonoscopy. Colonoscopy showed petechiae of the rectal mucosa, with pathologic examination of biopsy tissue showing calcified eggs of the genus Schistosoma. Direct examination of eggs in feces and antibody tests of serum confirmed the diagnosis of schistosomiasis. The patient was administered Praziquantel (400 mg/day for 2 days) and FOB and fecal ova tests were negative after treatment. FOB tests have been reported as a useful assessment of morbidities associated with intestinal schistosomiasis. In developed countries, positive FOB result, which is used as a main examination for bowel malignant disease, are not recognized as being due to schistosomiasis. As this tropical disease is rarely present in developed countries, it may be under-diagnosed. Schistosomiasis should be included in the differential diagnosis of patients with positive FOB tests.