Whipple's disease overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sadaf Sharfaei M.D.[2]
Overview
Whipple's disease is a rare, systemic infectious disease caused by the bacterium Tropheryma whipplei.[1] Whipple's disease primarily causes malabsorption but may affect any part of the body including the heart, lungs, brain, joints, and eyes.
Historical Perspective
Whipple described the disease for the first time in 1907 as a gastrointestinal disorder and named it as "intestinal lipodystrophy." Light and electron microscopy on small bowel biopsy were used to detect bacilli inside the intestinal mucosa. In 1952, systemic antibiotics were used to treat the disease which confirmed the infective nature of the disease. It took almost 100 years for investigators to cultivate the bacterium and sequenced the genome.
Classification
Whipple’s disease may be classified into 2 groups of acute and chronic infection. It might be classified as systemic or localized based on the organ involvement. It has 4 different clinical manifestations: Acute infection, asymptomatic carrier state, the classic Whipple’s disease, and localized chronic infection.
Pathophysiology
Whipple’s disease is a very rare disease. Therefore, some aspects of pathogenesis have remained unclear. Tropheryma whipplei is usually transmitted through oral route to human hosts. There is no known causative genetic factor for Whipple's disease. However, genetic and immunologic factors play important roles in clinical manifestation of Tropheryma whipplei infection. Individuals with positive HLA-B27 and defective cellular immunity including AIDS are at risk for Whipple's disease. Impaired macrophage function and cellular immunity are the main factors in replication of the bacteria and disease expansion to every tissue. There is a decreased activity of the T helper cells type 1 and increased activity of the T helper cells type 2. Defective phagocytic system is responsible for replication of bacteria in macrophages and spread of bacteria to other tissues. Characteristic of Whipple's disease is presence of foamy macrophages in the lamina propria that is periodic acid-Schiff stain positive.
Causes
Tropheryma whipplei is a bacterium and the causative organism of Whipple's disease. While Tropheryma whipplei is categorized with the Gram-positive Actinobacteria, the organism is commonly found to be Gram-negative or Gram-indeterminate when stained in the laboratory. Whipple himself probably observed the organisms as rod-shaped structures with silver stain in his original case, but no name was given to the organism until 1991 when the name Tropheryma whippelii was proposed after sections of the bacterial genome were sequenced. The name was changed to Tropheryma whipplei in 2001 (correcting the spelling of Whipple's name) after deposition in bacterial collections.
Differentiating Whipple's disease from other Diseases
Whipple's disease must be differentiated from other diseases that cause malabsorption, chronic diarrhea, abdominal pain, multisystem involvement, such as Celiac disease, Cystic fibrosis, inflammatory bowel disease and systemic infections.