Tropical sprue

Tropical sprue is a malabsorption disease commonly found in the tropical regions, marked with abnormal flattening of the villi and inflammation of the lining of the small intestine. It differs significantly from coeliac sprue.

Signs and symptoms

The illness usually starts with an attack of acute diarrhea, fever and malaise following which, after a variable period, the patient settles into the chronic phase of diarrhoea, steatorrhoea, weight loss, anorexia, malaise and nutritional deficiencies. The symptoms of tropical sprue are:

• Diarrhea
• Steatorrhea or fatty stool (often foul-smelling and whitish in colour)
• Indigestion
• Cramps
• Weight loss and malnutrition
• Fatigue

Left untreated, nutrient and vitamin deficiencies may develop in patients with tropical sprue. These deficiencies may have the following symptoms:

• Vitamin A deficiency: hyperkeratosis or skin scales
• Vitamin B₁₂ and folic acid deficiencies: anaemia
• Vitamin D and calcium deficiencies: spasm, bone pain, numbness and tingling sensation
• Vitamin K deficiency: bruises

Tropical sprue was responsible for one-sixth of all casualties sustained by the Allied forces in India and Southeast Asia during World War II.^[1]

Investigations

Diagnosis of tropical sprue can be complicated because many diseases have similar symptoms. The following investigation results are suggestive:

• Abnormal flattening of villi and inflammation of the lining of the small intestine, observed during an endoscopic procedure.
• Presence of inflammatory cells (most often lymphocytes) in the biopsy of small intestine tissue.
• Low levels of vitamins A, B₁₂, E, D, and K, as well as serum albumin, calcium, and folate, revealed by a blood test.
• Excess fat in the feces (steatorrhoea).
• Thickened small bowel folds seen on barium swallow

Tropical sprue is largely limited to within about 30 degrees north and south of the equator. Therefore, if one resides outside of that geographical region, recent travel to the region is a key factor in diagnosing this disease.

Cause

The cause of tropical sprue is not known.^[2] It has been suggested that it is caused by bacterial, viral, amoebal, or parasitic infection. Folic acid deficiency and rancid fat have also been suggested as possible causes.

In a condition called coeliac disease (also known as coeliac sprue), which has similar symptoms to tropical sprue, the flattening of the villi and small intestine inflammation is caused by an autoimmune disorder triggered by ingested gluten.

Affected regions

The disease was first described by William Hillary^[3] in 1759 in Barbados. Tropical sprue is endemic to the Caribbean, Central and South America, and India and southeast Asia.

Treatment

Once diagnosed, tropical sprue can be treated by a course of the antibiotic tetracycline or Sulfamethoxazole/Trimethoprim (Co-trimoxazole) for 3 to 6 months, as well as supplementation of vitamins B₁₂ and folic acid.

The use of folic acid in the treatment of tropical sprue was promoted in the late 1940s by Dr. Tom Spies of the University of Alabama, while conducting his research in Cuba and Puerto Rico.^[4][5]

Prevention

Preventive measures include using only bottled water for drinking, brushing teeth, and washing food, and avoiding fruits washed with tap water (or consuming only peeled fruits, such as bananas and oranges).

Prognosis

The prognosis for tropical sprue is excellent. It usually does not recur in patients who get it during travel to affected regions. The recurrence rate for natives is about 20%.

References

External links

• InteliHealth - Tropical Sprue
• Health In Plain English - Tropical Sprue
• Malabsorption Syndromes: Tropical Sprue at Merck Manual