Traveler's diarrhea

During a trip, our body is exposed to various stressors to which it will have to adapt, such as tropical climates with high humidity, different food, food storage that is not always adequate, and sanitary conditions that are not always safe. These factors that stress our digestive system and in particular make our intestines irritable, together with the risk of exposure to pathogens are crucial to the development of traveler's diarrhea. The etiological agents most involved are bacteria, such as Escherichia coli, Campylobacter jejuni, Shigella, Salmonella, which cause up to 80% of traveler's diarrhea. Viruses, such as Rotavirus, Norovirus, Astrovirus, Hepatitis A virus, cause about 10-15% of diarrhea, while parasitic agents, such as Giardia, Amoeba, Strongyloides account for the third leading cause of all traveler's diarrhea.

Transmission typically occurs via the fecal-oral route: the causative agent is excreted by infected individuals via feces and can go on to contaminate food and drink that are then consumed by healthy individuals.

The pathogens that can cause this unpleasant travel companion are ubiquitous throughout the world, but generally the destinations with the highest risk are in the tropical and sub-tropical area of the globe, from Asia, to the Middle East, Africa, Central and South America.

Diarrhea of bacterial and viral origin generally manifests with thesudden onset of bothersome symptoms such as abdominal cramps, unformed or watery stools, fever, vomiting, and general malaise. In cases where symptoms linger for several days, or particularly acute pain is experienced, it is desirable to contact a physician or infectivologist, possibly specializing in tropical medicine. Bacterial pathogens usually cause the first symptoms within a few hours, whereas for some protozoa such as Giardia or E. histolytica there is a longer incubation, such as 1-2 weeks (except for Cyclospora cayetanensis, which can occur rapidly in high-risk areas). The clinical course also differs depending on the pathogen, and its observation may be useful for diagnostic purposes. Untreated bacterial diarrhea generally can last up to 7 days, while viral diarrhea has a shorter course, averaging 2-3 days. In contrast, diarrhea caused by protozoa can persist for weeks or months in the absence of treatment.

Diagnosis starts from the patient's clinical picture and travel characteristics. Raised the suspicion of traveler's diarrhea, one can proceed with coproculture (the culture of stool), which allows to highlight the growth of E.Coli strains or other pathogens . In any case, specific laboratory tests are required to be able to identify the exact etiologic agent.

Treatment depends on the cause of the disease. For this reason, it is essential to diagnose the pathogen in order to appropriately and effectively treat the disease. Hydration is the primary intervention to be implemented, often with mineral salt supplementation. A strong indication also includes the concomitant use of milk enzymes and intestinal disinfectants. Particular attention should be paid toward children, the elderly, and those with chronic conditions. The CDC recommends for moderate diarrhea, after consultation with a physician, treatment with:

• Fluoroquinolones (Ciprofloxacin, Levofloxacin)
• Azithromycin
• Rifaximin (intestinal disinfectant antibacterial and the drug's trade names are: Normix, Flonorm, Rifaximin Ranbaxy and Tixtar)
• Neomycin and Bacitracin (intestinal disinfectant antibacterial and the trade name of the drug containing them is Bimixin)
• Loperamide, which should never be used alone but in addition to antibiotic therapy because it can only treat the symptom and not the cause (the drug's trade names are Imodium and Loperamide Angelini). Do not use if fever or blood in the stool is present

For travelers in high-risk areas, the CDC recommends several behaviors that can reduce, but never completely eliminate, the risk for traveler's diarrhea.

• Caution in food and beverage selection:
  • Prefer foods that are cooked and still hot;Wash fruits and vegetables thoroughly;
  • Whenever possible, peel fruits and vegetables;
  • Avoid raw meat, fish and unpasteurized products;
  • Avoid ice;
  • If traveling with an infant, prefer breastfeeding;
  • If the infant is formula-fed, reconstitute the powder with water brought to a temperature of at least 70°C;
  • Always sterilize bottles, baby bottles and pacifiers;
• Beware of water:
  • In areas where tap water may not be safe, use only bottled water from an unopened, sealed container for drinking, food and beverage preparation, ice, cooking, and brushing teeth;
  • Beverages prepared with freshly boiled water, such as tea and coffee, are generally safe to drink;
• Attention to hand hygiene
  • Travelers should wash their hands with soap and water before preparing food, before eating, after using the bathroom or changing diapers, before and after caring for someone who is sick, and after contact with animals or their environment;
  • If soap and water are not available, use an alcohol-based hand sanitizer (with alcohol ≥60%) and wash hands with soap and water as soon as they become available.

Vaccines are not available for most of the causative agents, but we do have access to very effective vaccines against these, such as Cholera, Salmonella, and Hepatitis A.