| Tropical sprue | |
|---|---|
| Other names | Postinfectious tropical malabsorption[1] |
| Specialty | Gastroenterology  |
| Symptoms | Diarrhoea, abdominal pain, weight loss |
| Complications | Malabsorption, anaemia |
| Diagnostic method | Intestinal histology |
| Differential diagnosis | Coeliac disease, environmental enteropathy |
| Treatment | Antibiotics, folate replacement |
Tropical sprue is amalabsorption disease commonly found in tropical regions, marked with abnormal flattening of thevilli andinflammation of the lining of thesmall intestine.[1][2] It differs significantly fromcoeliac sprue. It appears to be a more severe form ofenvironmental enteropathy.[3][4]
The illness usually starts with an attack of acutediarrhoea,fever andmalaise following which, after a variable period, the patient settles into the chronic phase of diarrhoea,steatorrhoea,weight loss,anorexia, malaise, and nutritional deficiencies.[1][2][3]The symptoms of tropical sprue are:
Left untreated, nutrient andvitamin deficiencies may develop in patients with tropical sprue.[1][2] These deficiencies may have these symptoms:
The cause of tropical sprue is not known.[2] It may be caused by persistent bacterial, viral, amoebal, orparasitic infections.[5]Folic acid deficiency, effects of malabsorbed fat onintestinal motility, and persistentsmall intestinal bacterial overgrowth may combine to cause the disorder.[6] A link betweensmall intestinal bacterial overgrowth and tropical sprue has been proposed to be involved in the etiology of post-infectiousirritable bowel syndrome (IBS).[7] Intestinal immunologic dysfunction, including deficiencies in secretory immunoglobulin A (IgA), may predispose people to malabsorption and bacterial colonization, so tropical sprue may be triggered in susceptible individuals following an acute enteric infection.[1]
Diagnosis of tropical sprue can be complicated because many diseases have similar symptoms. The following investigation results are suggestive:[1]
Tropical sprue is largely limited to within about 30 degrees north and south of theequator. Recent travel to this region is a key factor in diagnosing this disease in residents of countries outside of that geographical region.[2]
Other conditions which can resemble tropical sprue need to be differentiated.[4]Coeliac disease (also known ascoeliac sprue or gluten sensitive enteropathy), has similar symptoms to tropical sprue, with the flattening of thevilli andsmall intestine inflammation and is caused by anautoimmune disorder in genetically susceptible individuals triggered by ingestedgluten. Malabsorption can also be caused byprotozoan infections,tuberculosis,HIV/AIDS,immunodeficiency,chronic pancreatitis andinflammatory bowel disease.[2]Environmental enteropathy is a less severe, subclinical condition similar to tropical sprue.[2]
Preventive measures for visitors to tropical areas where the condition exists include steps to reduce the likelihood ofgastroenteritis. These may comprise using onlybottled water for drinking, brushing teeth, and washing food, and avoiding fruits washed with tap water (or consuming only peeled fruits, such asbananas andoranges). Basic sanitation is necessary to reduce fecal-oral contamination and the impact of environmental enteropathy in the developing world.[2]
Once diagnosed, tropical sprue can be treated by a course of the antibiotictetracycline orsulphamethoxazole/trimethoprim (co-trimoxazole) for 3 to 6 months.[2][8]Supplementation of vitamins B12 and folic acid improves appetite and leads to a gain in weight.[4][9]
The prognosis for tropical sprue may be excellent after treatment. It usually does not recur in people who get it during travel to affected regions. The recurrence rate for natives is about 20%,[2] but another study showed changes can persist for several years.[10]
Tropical sprue is common in theCaribbean, Central andSouth America, andIndia and southeastAsia. In the Caribbean, it appeared to be more common in Puerto Rico and Haiti. Epidemics in southern India have occurred.[2]
The disease was first described byWilliam Hillary[11] in 1759 inBarbados.[12] Tropical sprue was responsible for one-sixth of all casualties sustained by the Allied forces in India and Southeast Asia during World War II.[2] The use of folic acid and vitamin B12 in the treatment of tropical sprue was promoted in the late 1940s by Dr.Tom Spies of theUniversity of Alabama, while conducting his research in Cuba and Puerto Rico.[13][14][15]