Dr. Fang: The patient, a 33-yr-old white fewas admitted to George Washington University Hospital on January 3, 1978, with a 10 mo history of diarrhea and a 20 lb weight loss. In March, 1977, she noted a change from her normal pattern of one stool daily to passage of 1-2 brownish semiformed stools/day. The frequency of the stools increased to five-six times a day in September, 1977. She did not use drugs or drink alcohol. By October, 1977, she had developed epigastric cramps with intermittent nausea. Occasional vomiting began in November, 1977, and at one time, she vomited coffee ground material. She drank bottled water shipped from Arkansas. Her private physician obtained a barium enema and an oral cholecystogram in October, both of which were normal. An upper gastrointestinal series revealed an enlarged duodenal bulb and a dilated jejunum with thickened jejunal folds. No ulcers were seen. She was hospitalized on November 23, 1977, for a work-up of the diarrhea. Physical examination revealed occasional high-pitched bowel sounds and mild diffuse abdominal tenderness. The stool was hemoccult negative and negative for fat by Sudan stain. The hematocrit was 45; white blood count was 7,700; transaminases were normal; serum albumin was 4.2 g/dl; serum cholesterol was 194 mg/dl. A small bowel biopsy specimen obtained at the duode-