Overview
Recognise Whipple disease and travel-related malabsorption without collapsing them into a single tropical diagnosis, select tissue, molecular and stool tests with microbiology, and begin prolonged organism-specific therapy only with infection and gastroenterology expertise using current reference-laboratory, UKHSA, BNF and local imported-infection guidance.
Whipple disease is a rare chronic infection by T. whipplei, an actinomycete-related organism. The classic sequence is intermittent arthralgia followed years later by diarrhoea, weight loss, fever, lymphadenopathy, abdominal pain, hyperpigmentation or oedema. Cardiac, central nervous system, ocular and focal joint disease may dominate. Histology typically shows foamy macrophages in the lamina propria containing PAS-positive material, but treated or extra-intestinal disease can be patchy and other organisms can mimic the stain.
PCR increases sensitivity but changes meaning by compartment. Detection in saliva or stool can occur in asymptomatic carriage and is insufficient alone. Concordant duodenal tissue histology and PCR are stronger; blood, synovial fluid, valve tissue, vitreous or cerebrospinal fluid is selected for the clinical phenotype. Diagnosis should be agreed with a reference microbiology service because specimen handling, assay and contamination affect interpretation.
Travel-related malabsorption begins with a timeline rather than the obsolete assumption that residence in the tropics proves tropical sprue. Protozoa, helminths, HIV, TB, post-infectious change, coeliac disease unmasked during travel and inflammatory bowel disease all compete. Tropical sprue remains a diagnosis of exclusion in people with chronic diarrhoea and small-bowel mucosal injury in relevant endemic settings after infections and coeliac disease are excluded. Treatment and duration are specialist-led because relapse and resistance consequences are substantial.