Patients suffering from acute, symptomatic TS usually present gastrointestinal symptoms. Diarrhea is most frequently observed and is associated with malaise and fever. Subsequently, diarrhea partially subsides, but nausea, anorexia, abdominal pain and fatigue are experienced. Steatorrhea may be an important indication of TS .
Chronic TS results in nutrient deficiencies. Deficits concerning vitamin B12, folate and liposoluble vitamins are most commonly detected. Interestingly, vitamin B12 deficiencies are more pronounced in TS cases originating from the Caribbean. Patients that presumably contracted the disease in Asia more frequently present folate deficits. Nutrient deficiencies are often associated with weight loss, edema and stomatitis. Dehydration and general pallor may also be observed. Generally, patients do not associate their symptoms with previous travels to tropical climates since years may have passed.
TS may be diagnosed in people indigenous to endemic regions and those who traveled there. Because up to ten years may pass until manifestation of first symptoms, a thorough medical history has to be obtained. There are no pathognomonic symptoms of TS. While an acute diarrhea may be caused by TS, this is not sufficient to confirm this diagnosis. Therefor, chronic gastrointestinal problems need to be detected.
After clinical examination, blood samples need to be analyzed to check for megaloblastic anemia and nutritional deficiencies. The former corresponds to disturbances regarding formation and maturation of erythrocytes and is characterized by reduced hematocrit and hemoglobin values whereas erythrocytic cell volume and erythrocytic hemoglobin content are increased. Vitamin B12 and folate levels are usually decreased. Additionally, hypoalbuminemia may be detected.
In order to distinguish steatorrhea caused by malabsorption from chronic diarrhea, stool should be tested for its fat content. While excretion of more than 15 g stool fat per day is diagnostic for steatorrhea, less than 7 g stool fat per day rule out the latter. D-xylose absorption tests may be very helpful to confirm malabsorption. In more than 90% of TS patients, D-xylose absorption is altered. Radiographic imaging with contrast agents such as barium sulfate may reveal dilation of the small intestine, thickening of the intestinal folds and therefore segmentation of the contrast agent.
So as to confirm TS, an endoscopic examination is required. Mucosal lesions are generally present but differ greatly in manifestation . During the endoscopic examination, biopsies should be obtained for further analyses. Ongoing research focuses on non-invasive markers for small intestine integrity and function. In this line, Australian scientists proposed to utilize a 13 C-sucrose breath test to detect intestinal damage in children .
If patients present with symptoms of acute diarrhea, TS is rarely diagnosed. Instead, symptomatic treatment will be realized in order to compensate for fluid loss, electrolyte imbalances and symptomatic anemia. Symptoms may be sufficiently severe to require urgent attention and hospitalization.
Only when blood screens reveal low levels of vitamin B12 and folate as well as megaloblastic anemia, malabsorption may be suspected. Deficient nutrients may not be limited to those characteristic for TS and should be replaced (e.g., 5 to 10 mg folate, per os, qd; 1 mg vitamin B12, i.m., qw). If fluid therapy is not sufficient to compensate for hemodynamic disturbances or if a severe case of anemia is registered, blood or blood product transfusions may be required. The anemia should improve considerably upon compensation for nutrient deficiencies .
Causative treatment is difficult due to the fact that the etiology of TS is not yet understood. It has been reported that antibiotics are effective in TS treatment. This could, however, not be confirmed in patients who contracted the disease in southern India. Tetracycline has been recommended for TS treatment. It should be administered in high doses for up to two months (250 mg, per os, qid) and in somewhat lower doses (250 mg, per os, bid) for another four months . Tetracycline may be replaced with doxycycline. Antibiotic treatment may be extended to up to one year if the patient is improving but if the disease could not yet be cured after six months.
Relapses may occur. Therefore, any TS patient should be revised at least once a month. It should be verified if all nutrient deficiencies are indeed corrected, if water and electrolyte imbalances do not persist. If a patient does not respond at all after four weeks of treatment, differential diagnoses have to be considered.
The etiology of the disease is poorly understood. Endemic regions are India, Southeast Asia and the Caribbean. The fact that not only the indigenous population but also long-term visitors may contract TS led to the hypothesis of an infectious disease. To date, the most widely accepted hypothesis is that of enteropathogenic, toxin-producing coliform bacteria colonizing the small intestine, causing small intestine bacterial overgrowth and mediating mucosal damage. Such damage does not necessarily occur right after bacterial infection. Distinct genera of Enterobacteriaceae, mainly Enterobacter, Escherichia and Klebsiella have been associated with TS    .
In some cases, TS is detected in travelers that visited endemic regions months or even years before. It is surprising that the aforementioned are usually eliminated within days after infection but that they are able to persist for such a long time in the intestinal tract of TS patients. Thus, a variety of additional, as of yet unknown factors presumably affects symptom onset and disease progress. It has been speculated that other gastrointestinal infectious diseases may finally trigger TS. Further research has to be conducted to confirm this suspicion and to clarify the role of genetics, diet and environmental factors. Indeed, dietary fats and seasonal eating habits have been proposed to affect TS development.
Mucosal damage is associated with malabsorption of certain nutrients, particularly of vitamin B12 and folate, and these deficits cause megaloblastic anemia and other symptoms associated with nutrient deficiencies.
As its name suggests, TS is endemic to tropical regions, even certain areas inside tropical regions of India, Southeast Asia and the Caribbean. It may be detected in patients that traveled to the aforementioned regions, especially if stays exceeded one month.
The overall incidence of the disease has been decreasing. It has been suggested that immediate use of antibiotics to treat cases of traveler's diarrhea may account for this trend. However, since the etiology of the disease is only poorly understood, no reliable conclusions can be drawn at this moment.
Absolute numbers concerning incidence and prevalence of TS are difficult to obtain. For Puerto Rico, a prevalence of up to 8% has been estimated.
No differences have been detected regarding males and females or people of different races. TS mainly affects adults, but can occasionally be observed in children.
Enteropathogenic, coliform bacteria presumably trigger small intestine bacterial overgrowth and mucosal damage that finally cause the malabsorption syndrome TS. Possibly, an acute infection with the above mentioned bacteria provokes certain damage to the mucosal layer of jejunum and ileum. Subsequently, malabsorption of certain nutrients, particularly of vitamin B12 and folate, occur. Simultaneously, enteroglucagon levels increase and delay the intestinal transit. Small intestine bacterial overgrowth may result from delayed transit and an altered intestinal environment. Apparently, these processes not only depend on each other but also potentiate each other. In this context, folate deficiencies have been proposed to aggravate mucosal damage, which would re-initiate the vicious circle.
The physiological flora of the small intestine mainly consists in Streptococcus and Lactobacillus strains. Here, coliform bacteria are not part of the normal intestinal flora, but they are nevertheless commonly found. Coliforms are known to frequently trigger acute enteritis and subsequent diarrhea . In this context, pathogenicity cannot be ascribed to certain species of coliform bacteria. It's rather the specific strain that may have adopted the facility to release exotoxins and to adhere to the intestinal mucosa by transformation, possibly also by transduction and conjugation. Enterotoxins released by coliform bacteria in the small intestine are grouped into highly antigenic, heat labile toxins and less antigenic, heat stable toxins.
As has been indicated above, TS mainly affects jejunum and ileum. Less frequently, pathological lesions are found in the duodenum and in the distal ileum in close proximity to the ileocecal valve. Stomach and colon are rarely affected.
No direct evidence indicates that antibiotic prophylaxis can prevent tropical sprue.
Tropical sprues (TS) is a disease that may be diagnosed in people living in or traveling to certain parts of the Caribbean, India and Southeast Asia. It's etiology is poorly understood. The most widely accepted hypothesis is based on the assumption that patients become infected with enteropathogenic Enterobacteriaceae while staying in the above mentioned regions. A series of unknown factors may then trigger the disease in any moment and up to ten years after initial infection.
Pathohistologic examinations of tissue samples obtained from TS patients revealed severe mucosal damage in jejunum and ileum. Such damage is associated with malabsorption and thus results in nutrient deficiencies, particularly in vitamin B12 and folate deficits.
Acute TS is associated with diarrhea and fever. These symptoms subside and are often replaced with nausea, abdominal pain and fatigue. The latter corresponds to a symptomatic anemia that is caused by nutrient deficiencies.
TS may be suspected based on presentation, medical history and laboratory analysis of blood samples, but an endoscopic examination and biopsy analysis is necessary to confirm the diagnosis.
Treatment primarily consists in fluid therapy, correction of electrolyte imbalances and compensation for nutrient deficiencies. Prolonged antibiotic treatment is recommended for TS and usually shows good effects.
Tropical sprue (TS) is a rare disorder that may be diagnosed in people living in or traveling to certain parts of the Caribbean, India and Southeast Asia. It is not yet known how the disease is caused, but scientist suggest that TS may be initialized by an infection with certain bacteria such as enteropathogenic Escherichia coli strains. These bacteria may colonize the small intestine, adhere to the intestinal mucosa and release different toxins. This way, they are causing significant damage to the intestinal mucosa. Because one of the main functions of the small intestine is to absorb nutrients, it does not come as a surprise that nutrient deficiencies may result from lesions in jejunum and ileum. These nutrient deficits, however, affect different processes throughout the body, e.g. erythrocyte formation and maturation as well as enterocyte function. Thus, anemia may be developed and intestinal damage is further aggravated. To date, it is not understood why this chain of events is triggered in some patients while others are apparently able to eliminate the above mentioned bacteria within a few days.
Symptoms may manifest up to ten years after initial infection, i.e., after traveling to endemic regions. Acute diarrhea, malaise and fever are the earliest symptoms, but they are very unspecific. Diarrhea may partially subside before nausea, abdominal pain, light-colored, greasy stools and generalized fatigue are experienced. Patients presenting with such symptoms to their physician will receive fluid therapy and will be thoroughly examined in order to reveal the trigger of the symptoms. Therefore, blood samples will be analyzed. In case of TS, they may reveal nutrient deficiencies, particularly reduced vitamin B12 and folate levels, but also hemogram alterations due to the above mentioned anemia. In order to confirm diagnosis, however, an endoscopic examination has to be conducted, tissue samples have to be collected and analyzed microscopically.
If TS is confirmed, prolonged antibiotic treatment will be initiated. Any deficient nutrients will be replaced. Patients usually respond well but slow to such treatment, which is why it is generally administered for six months. During recovery, blood samples will be obtained regularly in order to detect possible relapses, nutrient deficiencies that remain without compensation and electrolyte imbalances.