William Hillary and sprue in the Caribbean: 230 years later

Sprue tropicale

Tropical sprue associates prolonged diarrhea, a malabsorption syndrome, and nutritional deficiency in patients who live in or have visited tropical areas. Pathogenesis is still unknown but an infectious cause is suspected. Macrocytic anemia and hypoalbuminemia are present, together with progressive villus atrophy of the small intestine. Treatment with tetracycline, folic acid and proper nutritional support generally results in full recovery.

Tropical malabsorption

Malabsorption is an important clinical problem both in visitors to the tropics and in native residents of tropical countries. Infections of the small intestine are the most important cause of tropical malabsorption. Protozoal infections cause malabsorption in immunocompetent hosts, but do so more commonly in the setting of immune deficiency. Helminth infections occasionally cause malabsorption or protein-losing enteropathy. Intestinal tuberculosis, chronic pancreatitis and small-bowel bacterial overgrowth are important causes of tropical malabsorption. In recent years, inflammatory bowel disease and coeliac disease have become major causes of malabsorption in the tropics. Sporadic tropical sprue is still an important cause of malabsorption in adults and in children in South Asia. Investigations to exclude specific infective, immunological or inflammatory causes are important before considering tropical sprue as a diagnosis. This article briefly reviews the management of tropical sprue and presents an algorithm for its investigation and management.

Tropical sprue

Tropical sprue (TS) is a clinical entity of unknown etiology characterized by an acquired chronic diarrheal illness and malabsorption that affects indigenous inhabitants and expatriates, either long-term residents or short-term visitors, in the tropical countries. The exact pathogenetic sequence of TS remains incompletely characterized. Bacterial overgrowth, disturbed gut motility, and hormonal and histopathologic abnormalities contribute to the development of TS in a susceptible host. Treatment with tetracycline and folate is effective in some patients, although relapses after treatment are common. Research in the areas of microbial factors, pathogenesis, immunogenetics, and hormonal and immune regulation, using modern diagnostic techniques, may be able to settle some of the unanswered issues and open new venues for diagnosis, prevention, and treatment of tropical sprue.

[Tropical sprue: two cases in the Paris area]

Tropical sprue (TS) is a postinfective tropical malabsorption that occurs in tropical countries. TS is associated with a persisting colonization of the small-intestine lumen by enterotoxinogenic bacteria that cause subsequent enterocyte damage affecting all or part of the small-intestine. We report two cases of TS that occurred in inhabitants of Paris area returned from endemic areas. The first observation concerned a 76-year old woman admitted for anorexia, loss of 20 kg and anemia. The second observation concerned a 53-year old man referred for chronic diarrhea and loss of 40 kg within 4 years. In both cases, duodenal lesions consisted of subtotal and total villous atrophy with prominent infiltration of the damaged surface epithelium with lymphocytes and infiltrate of lymphocytes and plasma cells of the lamina propria. The two patients recovered under antibiotics, confirming the diagnosis of TS.

Tropical Sprue

Tropical sprue is a disease that causes progressive villus atrophy in the small intestine, similar to nontropical (celiac) sprue. The loss of intestinal villi profoundly affects intestinal absorptive function, and patients with tropical or nontropical sprue present with malabsorption. Whereas the etiology of celiac sprue has been elucidated in considerable detail, the etiology of tropical sprue remains obscure. The favored hypothesis is that the disease is either initiated or sustained by a still-undefined infection. Patients with tropical sprue typically present with macrocytic anemia due to malabsorption of folate and/or vitamin B(12). Treatment of tropical sprue with folic acid replacement was introduced more than 50 years ago and has become standard medical treatment. Vitamin B(12) replacement is usually added if there is evidence of B(12) deficiency or malabsorption. Treatment of tropical sprue with folate and B(12) cures the macrocytic anemia and the accompanying glossitis, and often results in increased appetite and weight gain. However, even prolonged treatment with these vitamins fails to restore villus atrophy, and malabsorption usually persists. The benefit of antibiotic treatment of tropical sprue was first documented during World War II, when sulfonamides were used to treat epidemics of tropical sprue in British and Italian troops in India. Antibiotic treatment has since become the standard treatment, and tetracycline has replaced sulfonamides. The recommended length of treatment with tetracycline is 6 months and it is given in combination with folate. The treatment has been shown to normalize mucosal structure in the small intestine and resolve malabsorption in most patients with tropical sprue. However, there is a substantial relapse rate in treated patients who return to, or remain in, endemic areas in the tropics.

A perspective on tropical sprue

A diagnosis of tropical sprue, an infrequent affliction of inhabitants and travelers in tropical regions, should be considered in patients with a compatible history, malabsorption, and chronic diarrhea. It can occur in either endemic or epidemic form and can be preceded by acute gastroenteritis. The cause of tropical sprue is still unknown, although most data support an infectious etiology. Therapeutic experience is greatest with folic acid and tetracycline. Most patients can be expected to recover with proper nutritional support, although relapses and slow responses occur.

Tropical sprue and subclinical enteropathy: a vision for the nineties

Aside from infectious intestinal diseases with known etiology, there is a group of gastrointestinal disorders mainly affecting the small intestine of individuals predominantly living in and less often visiting or returning from the Third World, usually the tropics, and ranging from asymptomatic structural and/or functional abnormalities of the gastrointestinal mucosa (subclinical enteropathy, SE) to a fully symptomatic condition highlighted by malabsorption of nutrients with associated nutritional deficiencies responsive to folate and broad spectrum antibiotic treatment (tropical sprue, TS). Mounting evidence supports an infectious cause in many instances. The exact nature of the infection, whether initiated and/or perpetuated by enterotoxigenic coliform bacteria, virus(es) or a combination of these, is not clear. Further studies, including those using molecular techniques, are needed in order to clarify various aspects of these widely prevalent disorders.