Definition: A chronic systemic infection by a gram-positive bacterium, Tropheryma whippelii, mainly affecting the SMALL INTESTINE but also the JOINTS; CARDIOVASCULAR SYSTEM; and the CENTRAL NERVOUS SYSTEM. The disease is characterized by fat deposits in the INTESTINAL MUCOSA and LYMPH NODES, malabsorption, DIARRHEA with fatty stools, MALNUTRITION, and ARTHRITIS.