Travelers diarrhea is a polyethological infectious disease manifested by disorders in the digestive tract during travel to another climatogeographic zone. The main manifestation of the disease is a change in character, an increase in the multiplicity and volume of the stool. Nausea, abdominal pain, fever and vomiting are also characteristic. Diagnosis of the condition consists in finding an etiological agent, fixing the increase in the titer of antibodies. Treatment of pathology is mainly symptomatic (rehydration, antidiarrheal agents), if possible, verification of the pathogen – etiotropic (antibiotics, antiprotozoal drugs).
A09 Diarrhea and gastroenteritis of presumably infectious origin
Travelers diarrhea is an infection that occurs with a disorder of the digestive function of the body during the first two weeks of stay outside the country of residence. From 25% to 70% of tourists visiting foreign countries note the development of this syndrome. Nosology is found all over the world, but the predominant distribution area is the countries of Africa, Latin America and Asia. The smallest number of cases of this condition occur in Japan, Canada, the USA, European countries, Australia and New Zealand. The peak of the disease in tropical states is observed in the summer and the rainy season; the likelihood of developing diarrhea is related to living conditions, nutrition and the nature of activity.
The most common causative agents of the disease are E. coli bacteria (E. coli), which account for 10 to 50% of cases of diarrhea. Viral causes of the disease – rota and norovirus lesions (10-40%) are the next most common, especially in cases of infections during sea cruises. The proportion of other bacterial agents (salmonella, campylobacteria, non-choleric vibrions), protozoa (amoebas, giardia, cryptosporidia, cyclospores) and unidentified infectious agents may account for 1-20% of cases of diarrhea. The source of infection is a person who is sick or an asymptomatic carrier of the pathogen.
The traditional ways of transmission are considered food (salads, unwashed vegetables, fruits, meat, fish dishes) and water (ice, milk, water, juices), special importance is attached to the place of preparation (most often the victims indicate that they ate “street” food, used drinking fountains, swallowed water when bathing, washing in the shower, brushing teeth). Risk groups for the development of the disease are people with the first blood group, increased interleukin-8 formation, children under 2 years old, young adults (20-39 years old), patients with gastritis with reduced secretory function of the stomach, immunodeficiency (including HIV infection).
The main links in the pathogenesis of diarrhea of any infectious etiology are impaired absorption of water and nutrients (viral lesions) and the release of protein and electrolytes from the blood plasma into the intestinal lumen (escherichiosis, giardiasis). Often there is a local or diffuse inflammation of the intestine (bacteria, protozoa). The toxins produced are of great importance: thus, the protein of enteroinvasive E. coli contributes to the formation of erosions in the intestinal wall, the toxin of enterohemorrhagic E. coli damages the endothelium of the vessels of the colon, which can lead to necrotic changes in the intestinal wall. Rotaviruses and noroviruses are able to block the enzyme systems of enterocytes, resulting in lactase deficiency. The channel-forming protein and cysteine proteinase of amoebas are capable of forming crater-like defects in the mucosa of the large intestine with a necrosis zone up to the muscle layer.
The incubation period of the disease can range from several hours to 20 days. The onset of the disease is usually acute, with an increase in body temperature (38 ° C and above), chills, weakness, decreased appetite, body aches. Then nausea, vomiting, pain and rumbling in the abdomen (most often in the umbilical region), loose stools join. The nature of diarrhea varies depending on the etiological factor: from watery, fetid, copious stool with undigested fragments of food to meager, with an admixture of blood, mucus and pus. The frequency of stool depends on the infectious dose of the pathogen and the immune reactivity of the body and is usually three or more times a day.
Viral diarrhea can occur with symptoms of upper respiratory tract damage (runny nose, sore throat, dry cough). Prognostically unfavorable factors are considered to be an increase in the frequency of vomiting and acts of defecation, the appearance of pronounced thirst, dry skin and mucous membranes, hoarseness of voice, limb cramps, decreased skin elasticity (turgor) and the amount of urine. In young children, dangerous symptoms are refusal to eat and drink, drowsiness, silent crying, convulsions.
Travelers diarrhea occurs mainly in mild or moderate form; the aggravation of the course of the disease occurs due to untimely treatment to a doctor, self-medication, background pathology and a hot climate. 3-10% of those affected after the disease may develop irritable bowel syndrome, reactive arthritis, Guillain-Barre disease. Dehydration, infectious and toxic shock, acute renal failure, intestinal bleeding, peritonitis, sepsis are much less common.
Diagnosis of the syndrome requires consultation of an infectious disease specialist, gastroenterologist, surgeon – in the presence of symptoms of irritation of the peritoneum. A thorough collection of epidemiological anamnesis is required; often this is enough to make a correct diagnosis. The necessary laboratory and instrumental studies are presented by the following methods:
- Objective inspection. Physical examination evaluates the degree of dehydration (shade, turgor, moisture of the skin, mucous membranes, limb cramps, hoarseness of voice), the presence or absence of peritoneal signs (symptoms of Shchetkin-Blumberg, Sitkovsky, Voskresensky and others), blood pressure, pulse. With travelers diarrhea, soreness in the navel area, along the course of the large intestine, rumbling, bloating is most often determined. Visual assessment of bowel movements for the presence of blood, mucus, pus is necessary.
- General clinical studies. The general blood test remains within the physiological norm, a slight acceleration of ESR may appear. The presence of leukocytosis and a high index of hemoglobin and erythrocytes may signal a pronounced degree of dehydration. Among the biochemical parameters of the blood, violations of the electrolyte composition are recorded, in severe cases, a decrease in the level of total protein, an increase in creatinine, ALT, AST, changes in acid-base balance. The general analysis of urine usually does not change; in the case of large fluid losses, the relative density of urine increases. The coprogram may demonstrate steatorrhea, the presence of a large number of undigested fiber and muscle fibers; it is also possible to increase the number of leukocytes, erythrocytes.
- Identification of infectious agents. Microscopic examination of native feces makes it possible to detect protozoan cysts. To verify bacterial damage, it is necessary to sow feces, gastric lavage, bile and vomiting on nutrient media. At the same time, PCR diagnostics is carried out to confirm the viral nature of the infection (there are also immunochromatographic express tests). ELISA and other serological studies are carried out for the purpose of differential diagnosis; with a known pathogen, it is possible to record a dynamic increase in the titer of antibodies in paired sera.
- Endoscopic methods. They are used for severe and prolonged diarrheal syndrome. Rectoromanoscopy and colonoscopy can detect inflammatory bowel changes, the presence of ulcers, necrotic areas of the mucosa.
Differential diagnosis is carried out with intestinal infections, Crohn’s disease, ulcerative colitis, ischemic disorders in the colon and small intestine (thrombosis, atherosclerosis), enteropathy, Whipple’s disease, pancreatitis, malignant neoplasms of the gastrointestinal tract, decompensation of diabetes mellitus. Surgical pathology, the symptoms of which are similar to the manifestations of travelers diarrhea, includes mesenteric thrombosis, perforation of gastric or duodenal ulcers, acute appendicitis and cholecystitis.
Travelers diarrhea treatment
Patients are subject to hospitalization only in case of severe course, chronic diseases, pregnancy, childhood and epidemiological indications. Of great importance is the diet, which implies a gentle food regime with the exception of heavy, hard-to-digest food, fresh fruits and vegetables, juices, cocoa-containing products. Frequent fractional meals are allowed, food should be served in stewed, baked, boiled form. It is recommended to correlate the drinking regime with the lost liquid and make up for the losses with warm boiled water with the addition of oral rehydration agents.
Bed rest is necessary for up to 1-3 days of sustained absence of fever. Etiotropic therapy depends on the infected agent, drugs are usually not prescribed without laboratory diagnostics. With proven bacterial and protozoal nature, antibiotics are used (most often fluoroquinolones, cephalosporins, macrolides, imidazoles), in the case of viral etiology, the use of antiviral agents has no proven effectiveness. To relieve dehydration of 2-3 degrees, rehydration infusions (chlosol, acesil, trisol), diarrheal and pain syndrome – sorbents (activated charcoal, smectite) and antispasmodics (drotaverine), enzyme preparations (lipase, pancreatin) are used.
Prognosis and prevention
The prognosis of travelers diarrhea is usually favorable. The duration of the disease in 90% of cases is no more than one week, recovery within a month is noted in 98% of patients. Severe course occurs in patients who have sought medical help late, are self-medicating or do not comply with doctors’ prescriptions for nutrition and rehydration.
Specific prophylaxis (vaccination) has not been developed, with the exception of a vaccine against rotavirus infection (only for children). Tourists traveling to countries with a high incidence rate are recommended to take prophylactic antibacterial agents before, during and after arrival (in total, no more than a month). The drugs of choice are rifaximin, norfloxacin, ciprofloxacin, less often azithromycin. Measures of non-specific prevention consist in observing the rules of personal hygiene (washing hands with soap before eating, using bottled water for washing, brushing teeth, processing vegetables and fruits), food hygiene (refusing to eat food cooked in unsanitary conditions, dairy products, ice). Bathing in stagnant reservoirs and swallowing water while diving is not recommended.