Unusual systemic disease involving tissues that have large glycoprotein-containing macrophages and Tropheryma whippleii, which are small, rod-shaped, gram-positive, non-acid fast organisms. Disorder marked by variable occurrence of abdominal pain, diarrhea, weight loss, intestinal malabsorption, CNS involvement, hyperpigmentation, lymphadenopathy, anemia, arthralgias, pericarditis, pleuritis, and visual deterioration. Abdominal manifestations in small intestine and mesenteric lymph nodes include granulomatous inflammation, fatty degeneration, and chyle stasis. Biopsy of mucosa of duodenum or jejunum provides best tissue for diagnosis. Antibiotic treatment varies widely but should probably include 3rd-generation cephalosporin and/or TMP-SMZ for 6Ð12 months.