Tropical sprue

Tropical sprue is a malabsorption syndrome that primarily occurs in tropical regions such as South Asia and the Caribbean. The exact cause is unknown. Tropical sprue typically manifests with chronic diarrhea, progressive weight loss, anorexia, and features of nutritional deficiencies such as anemia, neuropathy, and bone disease. Diagnosis is based on the clinical presentation, evidence of malabsorption, and characteristic histological findings on a small bowel biopsy (e.g., villous atrophy), after other causes have been excluded. Management focuses on correcting fluid, electrolyte, and nutritional deficits, along with a prolonged course of antibiotics (e.g., tetracycline) and supplementation with folic acid and vitamin B₁₂.

Tropical sprue is a disease characterized by chronic diarrhea with subsequent malabsorption in association with a stay in the tropics or subtropics.

• The exact cause is unknown, but it is believed to be multifactorial. ^[1][2]
• Potential associations ^[1]
  • May occur after an episode of acute bacterial gastroenteritis that leads to structural damage of the intestinal mucosa
  • Gut dysbiosis, including small intestinal bacterial overgrowth
  • Protozoal, fungal, or viral exposures

• Chronic diarrhea ^[1][2]
• Progressive weight loss ^[1][2]
• Abdominal cramps
• Anorexia ^[1]
• Fatigue ^[1]
• Features of malabsorption and nutritional deficiencies ^[1]
  • Anemia
  • Neuropathy
  • Bone disease
  • Proximal muscle weakness (due to potassium deficiency)

Celiac disease and tropical sprue have similar features (e.g., steatorrhea, abdominal pain, weight loss), but only tropical sprue responds to antibiotics.

The diagnosis is established based on characteristic clinical features, laboratory evidence of malabsorption, characteristic histological findings, and the exclusion of other causes. ^[1][2]

Laboratory studies

• Blood tests: to assess for malabsorption and nutritional deficiencies and rule out differential diagnoses ^[1][2]
  • CBC: megaloblastic anemia
  • ↓ Vitamin B₁₂
  • ↓ Folate
  • Hypoalbuminemia
  • Hypocalcemia
  • Vitamin D deficiency
  • Celiac disease serology
• Stool analysis
  • Fecal fat 10–40 g/day
  • Diagnostics for infectious gastroenteritis: stool culture and/or PCR for pathogens such as Giardia lamblia and Entamoeba histolytica

Small bowel endoscopy with biopsies ^[2]

• Histological findings: villous atrophy, elongated crypts, inflammatory cells (plasma cells, lymphocytes, eosinophils)
• Mainly affects the duodenum and jejunum but may progress to the ileum

• Celiac disease
• Small intestinal bacterial overgrowth
• Small intestinal fungal overgrowth
• Environmental enteropathy (tropical enteropathy)
• Autoimmune enteropathy
• Drug-induced enteropathy (e.g., NSAID-induced enteropathy)

The differential diagnoses listed here are not exhaustive.

• Fluid and electrolyte repletion as needed ^[1]
• Tetracycline for 2 months ^[1]
• Vitamin supplementation ^[1][2]
  • Folic acid
  • Vitamin B₁₂
• Nutritional support to treat malnutrition, e.g.: ^[1]
  • Restriction of long-chain fatty acids (may reduce steatorrhea)
  • Supplementation with medium-chain triglycerides

• Malnutrition ^[1]
• Anemia (from folate and/or vitamin B₁₂ deficiency)^[1][2]
• Neuropathy from vitamin B₁₂ deficiency ^[1]
• Bone disease (e.g., osteomalacia) from calcium and vitamin D malabsorption ^[1]

We list the most important complications. The selection is not exhaustive.