Traveler's Diarrhea

Generality

Traveler's diarrhea is an "enteritis (infectious disease of the digestive tract) that affects people from highly hygienic countries when they travel to developing areas. The areas at greatest risk are Southeast Asia, India. , Bangladesh and some countries of Africa and Central America, in particular Mexico; the syndrome is particularly frequent also in North Africa and in the Middle East area.

It is estimated that around 6 million people are affected each year, of which 30% are bedridden. In most cases, strains of a bacterium called Escherichia Coli and known as ETEC (Enterotoxigenic E.Coli) strains, which produce an enterotoxin, which is a molecule toxic to the digestive system.

Traveler's diarrhea manifests itself with secretory diarrheal syndromes of varying severity, sustained by strains of E. Coli that do not invade the intestinal mucosa, but capable of causing alterations in intestinal transit through the production of enterotoxins.
In reality, however, the cause of traveler's diarrhea is variable and can be in 80% of cases of bacterial origin (in particular enterotoxigenic strains of E. coli and less frequently Salmonella, Campylobacter, Staphylococci), but also viral (Rotavirus) or from protozoa (parasites); in some cases it can be multiple.

The most severe form is usually the one sustained by Campylobacter and the mildest from enterotoxic E.Coli (ETEC).

Epidemiology

Enterotoxigenic strains of E. coli are ubiquitous (they are found everywhere), even if their frequency varies in different geographical areas: they are particularly widespread in the countries of the South of the world, probably also due to the lower hygienic level observable in the populations resident there, and constitute the most frequent cause of bacterial diarrhea worldwide.

Read more: Which countries are at greatest risk for traveler's diarrhea?

"Traveler's diarrhea" is the most frequent clinical problem during travel, with a much higher risk for those occurring in tropical areas, where food and drink hygiene is not always perfect.

Risk factors

In addition, other problems such as the lack of sanitation infrastructure make it easier to contaminate water and food.

Factors may favor the extreme ages of life (children and the elderly), hypochlorhydria (the poor production of hydrochloric acid by the stomach), a deficit of the immune system and the adoption of lifestyles of local populations.

To learn more: Traveler's diarrhea: what are the risk factors?

Infection

Transmission is mostly fecal-oral: the infectious agent is eliminated with the feces by the sick subject and whoever is infected comes into oral contact with the contaminated material of the same infected feces.

The transmission of the disease is therefore mainly linked to the quality of the water and drinks consumed. Among the non-infectious causes, the change in eating habits and travel-related stress play an important role, which can exacerbate a pre-existing infectious diarrhea or bring out a Quiescent intestinal pathology The enterotoxigenic strains of E.Coli are however widespread also in industrialized countries, where they can sustain both more or less extensive epidemics as well as sporadic cases in adults and children.

Mode of action of E.Coli

E. coli is a Gram Negative bacillus, that is, it has an elongated shape and is colored red with the Gram stain, and belongs to the family of Enterobacteria (Enterobacteriaceae). It is widespread in nature and is a normal inhabitant of the bacterial flora of the human intestine, as well as of the urinary tract, skin and vagina. The enterotoxigenic strains of E.Coli (ETEC) are capable of producing one or two distinct toxins of protein nature: the thermostable toxin (TS) and the thermolabile toxin (LT), similar to that of cholera and capable of causing the secretion of chlorine and water in the lumen of the intestine. In addition to the production of enterotoxins, other factors seem necessary to cause the disease, including the ability of ETEC strains to adhere to epithelial cells of the small intestine. Due to the absence of invasive properties, ETEC strains are very rarely involved in extra-intestinal infections from E. coli.

Symptoms

To learn more: Traveler's Diarrhea Symptoms

The onset is generally acute, brutal, after a short incubation period (24-48 hours), and is characterized by the presence of watery diarrhea, accompanied by crampy abdominal pain and sometimes even by vomiting and low-grade fever. light in color, they do not contain mucus, blood or white blood cells; the number of daily discharges is widely variable, but usually is between 4 and 8 in the 24 hours. Symptoms appear more frequently during the first days of the trip (2 ° -10 ° day).

Curiosity: Find out why traveler's diarrhea is also called "Montezuma's revenge"

Diagnosis

The diagnostic assessment of suspected cases on the basis of epidemiological and clinical pictures is carried out through coproculture (faecal culture), which often allows to highlight the growth of E. coli strains belonging to the enterotoxigenic ones. Only special methods performed in laboratories However, experts can demonstrate the precise mechanism responsible for individual cases; in this regard, tests (radioimmunological and immunoenzymatic) capable of identifying strains producing thermolabile and thermostable toxins have only been on the market for a few years.

Course and prognosis

In the adult the course is usually benign: the symptoms subside in 24-48 hours and disappear within a few days. In children, and in particular in infants, the clinical picture can be complicated by the onset of dehydration and alterations in the water balance. and salts, which can evolve towards a clinical picture that can closely resemble that of cholera. "Traveler's diarrhea" usually has a rapid spontaneous recovery (3-4 days); in 10% of cases it can last for more than 1 week.

Care and Therapy

To learn more: Medicines for the treatment of Traveler's Diarrhea

Treatment is mainly symptomatic and based on rehydration (administration of fluids by mouth and via drip) and on the reintegration of salts lost in faeces and vomit (especially potassium); antispasmodics and antidiarrheals are also useful, as well as lactic ferments supplements to restore the integrity of the intestinal flora. In severe forms of the infant, both rehydration therapy and supplementation with salts must be carried out according to the schemes usually used in cholera. Antibiotic therapy is indicated in cases where the symptoms are very pronounced and / or protracted over time: in adults the first choice drugs are fluoroquinolones, in children cotrimoxazole. If diarrhea is profuse (more than 4 discharges per day) and symptomatic therapy is not resolved after 2-3 days, antibiotic treatment with a fluoroquinolone is recommended (ciprofloxacin or norfloxacin); the "early" empirical therapy with a single dose of quinolone is not shared by all.

Prevention

Prevention is based on hygiene rules suitable for reducing the onset and spread of infection in pediatric communities (control of both personnel and linen, immediate isolation of infected cases); it is also based on compliance with simple food hygiene rules and on the prophylactic use of drugs in selected cases. In countries at risk, the consumption of water and other beverages of dubious origin which are not sterilized or contained in sealed bottles should always be avoided possible for some hygienic practices such as cleaning the oral cavity, as well as for the ingestion of raw vegetables, fruit that cannot be peeled, raw meat and fish, seafood, cheeses and artisanal ice creams; as a precaution, the prohibition can be extended to any kind of food prepared or sold outdoors. Prophylaxis with single dose fluoroquinolones (the doxycycline and the cotrimoxazole, once used, are now less effective due to the widespread diffusion of antibiotic resistance than E. coli) is not recommended in all subjects who go to areas at risk, given the potential toxicity of drugs and the risk of facilitating appearance of resistance; it should instead be reserved for subjects at risk of serious forms, such as people suffering from chronic inflammatory bowel diseases from HIV / AIDS or with gastric hypoacidity, even pharmacologically induced, as well as for those who for work reasons cannot suspend their activity even for short periods Vaccines against enterotoxigenic E.Coli strains are not yet available: partial coverage from traveler's diarrhea is provided by the oral cholera vaccine.