Parasitic rheumatism presenting as rheumatoid arthritis.

A symmetrical polyarthritis with low titer positive rheumatoid factor occurred in a young man who also complained of chronic diarrhea after returning from Vietnam. Endolimax nana grew on stool culture. Both the patient's diarrhea and arthritis responded effectively to therapy with metronidazole. The diagnosis of parasitic rheumatism was made in retrospect. Diagnostic consideration should be given to this entity in patients with unusual arthropathies, particularly if they have stayed in an endemic parasitic country and have gastrointestinal symptoms.