OVERVIEW
• Tropical sprue is a rare condition marked by swelling and inflammation of the intestines.
• It is believed to be caused by chronic infection of the small bowel due to toxigenic strains of coliform bacteria
• Clinical features mainly include malabsorption and megaloblastic anemia.
• Diagnosis is made by clinical history/examination and small bowel biopsy.
• Management is with tetracycline and folic acid for 6 months.
• Tropical sprue is seen predominantly in southern India, the Caribbean and Southeast Asia, and affects natives as well as visitors

PATHOGENESIS
• The exact mechanism of initiation and propagation of the disease remains unclear. One hypothesis is that an acute intestinal infection leads to jejunal and ileal mucosal damage and injury followed by intestinal bacterial overgrowth resulting in malabsorption.
• Key to this pathogenesis is folate deficiency, which can contribute to further mucosal injury.
• Hormones enteroglucagon and motilin are increased in patients with tropical sprue. Injury to intestinal epithelium can cause these elevations. Enteroglucagon causes stasis of intestines, but the role of motilin remains unclear.
• The upper small intestine is predominantly affected. However, since it is a progressive and involves contiguous areas, the distal small intestine up to the terminal ileum may be involved.
• Pathological changes are rarely seen in the stomach and colon.
• Coliform bacteria, such as Klebsiella, E coli and Enterobacter species are the usual organisms associated with tropical sprue.

CLINICAL FEATURES
Symptoms of tropical sprue may include
• Abdominal pain
• Bloating and excessive flatulence
• Chronic diarrhea worsened by high-fat diet
• Poor digestion
• Weight loss
• Pallor and weakness
• Irritability
• Muscle aches and cramps
• Numbness and tingling of extremities

DIFFERENTIAL DIAGNOSIS
• Giardiasis
• Crohn’s disease
• Ulcerative colitis
• Irritable bowel syndrome

Bowel imaging studies and histopathological examination can help to rule out other possible conditions with similar presentation

DIAGNOSIS
TESTS FOR MALABSORPTION
One of the ways to diagnose tropical sprue is to check for nutritional deficiencies caused by the malabsorption. Tests include
• Complete blood count
• Bone density
• Vitamin D levels
• Folate level
• Vitamin B12 level

UPPER GI ENDOSCOPY
A thin tube is introduced through the mouth into the gastrointestinal tract. This helps the doctor to look for any abnormalities in the small intestine. A small sample of small bowel tissue may be removed (biopsy) and analyzed by histopathological examination. In tropical sprue, there may be features of swelling and inflammation in the lining of the small intestine.

SMALL BOWEL IMAGING
Barium meal and small-bowel follow-through studies may reveal segmentation of the barium, dilation of the lumen, and thickening of the mucosal folds but these findings are not specific for tropical sprue.

D-XYLOSE ABSORPTION TEST
The test is abnormal in over 90% of cases but is again non-specific

TREATMENT
ANTIBACTERIALS
Tropical sprue is treated with antibiotics for a period of two weeks to one year. It helps to kill the bacterial overgrowth in the intestines.
Tetracycline is the most commonly used antibiotic to treat tropical sprue. It’s cheap, effective and widely available. Other broad-spectrum antibiotics that can be used include
• Ampicillin
• Sulfamethoxazole and trimethoprim (Bactrim)
• Oxytetracycline

TREATMENT OF MALABSORPTION
While treating the bacterial overgrowth, deficiencies caused by the malabsorption have to be corrected. These may include
• Iron
• Folate
• Fluids and electrolytes
• Vitamin B12
• Vitamin D supplements

Medications to control diarrheal symptoms

PROGNOSIS
The main complications of tropical sprue are vitamin and mineral deficiencies due to malabsorption resulting in growth failure and issues with bone maturation in children.
With proper treatment, the long term prognosis is very good. According to the Postgraduate Medical Journal, most people show positive outcomes within three to six months following initiation of treatment.