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.
Epidemiology and Demographics
Whipple's disease is an extremely rare disease among middle-aged white males in North America and western Europe. It affects males 8 times more than females. Few studies were done to evaluate the demographics of Whipple's disease due to the sparsity of the disease. The incidence of Whipple's disease is approximately 0.1 per 100,000 individuals and the prevalence is approximately 0.3 per 100,000 individuals in north-western Italy. Although the prevalence of carrier state is higher in Asian and African countries, the prevalence of the classic Whipple's disease is less than American and western European countries. It is a fatal disease, if left untreated.
Risk Factors
Common risk factors in the development of Whipple's disease may be environmental, genetic, and immunologic. The most important risk factor in the development of Whipple's disease is poor sanitation including living in homeless shelters and absence of toilets. Defective cellular immunity is the less common risk factor.
Screening
There is insufficient evidence to recommend routine screening for Whipple's disease.
Natural History, Complications, and Prognosis
Tropheryma whipplei infection has different clinical manifestations. It could cause acute infection, localized infection and the classic Whipple's disease. Acute infection might present with gastroenteritis, pneumonia or bacteremia. Classic Whipple's disease has 3 clinical phases that starts with nonspecific symptoms and joint pain. It progresses to gastrointestinal symptoms such as diarrhea, steatorrhea, malabsorption, and weight loss. in the late phase, all the other organs including CNS, joints, eyes, heart, lung, liver and skin might be involved. Without treatment, whipple's disease is fatal. Long-term antibiotic therapy successfully limits the replication of the bacteria and cure the disease. However, relapse of Whipple's disease might occur after treatment in approximately 40% of patients.
Diagnosis
Diagnostic Criteria
There are no established criteria for the diagnosis of Whipple's disease.