1. From the Divisions Pediatric Gastroenterology and Nutrition and
2. Combined Program in Pediatric Gastroenterology and Nutrition,
3. University of Massachusetts, Lowell, Massachusetts.
4. Division of Clinical Epidemiology, Brigham and Women's Hospital, Harvard, Medical School, Boston, Massachusetts;
5. Pediatric Infectious Diseases, University of Rochester Medical Center, Rochester, New York;
6. Division of Infectious Diseases, Children's Hospital, Harvard Medical School, Boston, Massachusetts;
7. Department of Infectious and Community Medicine, Tufts University School of Medicine, Boston, Massachusetts; and the