Travelers Diarrhea

 

Travelers’ Diarrhea

Description

Travelers’ diarrhea (TD) is the most predictable travel-related illness. Attack rates range from 30% to 70% of travelers, depending on the destination. Traditionally, it was thought that TD could be prevented by following eating rules, but studies have found that people who follow the rules still get ill. Poor hygiene practice in local restaurants is likely the largest contributor to the risk for TD.
TD itself is a clinical syndrome that can result from a variety of intestinal pathogens. Bacterial pathogens are the predominant risk, thought to account for 80%–90% of TD. Intestinal viruses have been isolated in studies of TD, but they usually account for 5%–8% of illnesses. Protozoal pathogens are slower to manifest symptoms, and collectively account for about 10% of diagnoses in longer-term travelers. What is commonly known as “food poisoning” involves the ingestion of preformed toxins in food. In this syndrome, vomiting and diarrhea may both be present, but symptoms usually resolve spontaneously within 12 hours.

Infectious Agent

bulletBacteria are the most common cause of TD. The most common pathogen is enterotoxigenic Escherichia coli, followed by Campylobacter jejuni, Shigella sp., and Salmonella sp. Enteroadherent and other E. coli species have been found to also be common pathogens in bacterial diarrhea.
bulletViral diarrhea can be caused by a number of viral pathogens, including norovirus, rotavirus, and astrovirus.
bulletGiardia is the main protozoal pathogen found in travelers. Entamoeba histolytica is a relatively uncommon pathogen in travelers. Cryptosporidium is also relatively uncommon. The risk for Cyclospora is highly geographic and seasonal, with the most well-known risks in Nepal, Peru, Haiti, and Guatemala. Dientamoeba fragilis is a low-grade but persisent pathogen that is occasionally diagnosed in travelers.
bulletThe individual pathogens are each discussed in their own sections in Chapter 5, and persistent diarrhea is discussed in Chapter 4.

Occurrence

bulletThe most important determinant of risk is travel destination, and there are regional differences in both the risk for and etiology of diarrhea.
bulletThe world is generally divided into three grades of risk: low, intermediate, and high.
bulletLow-risk countries include the United States, Canada, Australia, New Zealand, Japan, and countries in Northern and Western Europe.
bulletIntermediate-risk countries include those in Eastern Europe, South Africa, and some of the Caribbean islands.
bulletHigh-risk areas include most of Asia, the Middle East, Africa, Mexico, and Central and South America.

Risk for Travelers

Travelers’ diarrhea occurs equally in male and female travelers and is more common in young adults than in older people. In short-term travelers, bouts of TD do not appear to protect against future attacks, and more than one episode of TD may occur during a single trip. A cohort of expatriates taking up residence in Kathmandu, Nepal, experienced an average of 3.2 episodes of TD per person in their first year. In more temperate regions, there may be seasonal variations in diarrhea risk. In South Asia, for example, during the hot months preceding the monsoon, much higher TD attack rates are commonly reported.
In environments where large numbers of people do not have access to plumbing or outhouses, the amount of stool contamination in the environment will be higher and more accessible to flies. Inadequate electrical capacity may lead to frequent blackouts or poorly functioning refrigeration, which can result in unsafe food storage and an increased risk for disease. Inadequate water supplies can lead to the absence of sinks for handwashing by restaurant staff. Poor training in handling and preparation of food may lead to cross-contamination from meat and inadequate sterilization of food preparation surfaces and utensils. In destinations in which effective food handling courses have been provided, the risk for TD has been demonstrated to decrease. It should be noted, however, that pathogens that cause TD are not unique to developing countries. The risk of TD is associated with the hygiene practices in specific destinations and the handling and preparation of food in restaurants in developed countries as well.

Clinical Presentation

bulletBacterial diarrhea presents with the sudden onset of bothersome symptoms that can range from mild cramps and urgent loose stools, to severe abdominal pain, fever, vomiting, and bloody diarrhea.
bulletViral enteropathogens present in a similar fashion to bacterial pathogens, although with norovirus vomiting may be more prominent.
bulletProtozoal diarrhea, such as that caused by Giardia intestinalis, or Entamoeba histolytica, generally has a more gradual onset of low-grade symptoms, with 2–5 loose stools per day.
bulletThe incubation period of the pathogens can be a clue to the etiology of TD.
bulletBacterial and viral pathogens have an incubation period of 6–48 hours.
bulletProtozoal pathogens generally have an incubation period of 1–2 weeks and rarely present in the first few weeks of travel. An exception can be Cyclospora cayetanensis, which can present quickly in areas of high risk.
bulletUntreated bacterial diarrhea lasts 3–5 days. Viral diarrhea lasts 2–3 days. Protozoal diarrhea can persist for weeks to months without treatment.
bulletAn acute bout of gastroenteritis can lead to persistent gastrointestinal symptoms, even in the absence of continued infection (see the Persistent Travelers’ Diarrhea section in Chapter 4). Other postinfectious sequelae include reactive arthritis and Guillain–Barré syndrome.

Food and Beverage Selection

Care in selecting food and beverages for consumption might minimize the risk for acquiring TD. Travelers should be advised that foods that are freshly cooked and served piping hot are safer than foods that may have been sitting for some time in the kitchen or in a buffet. Care should be taken to avoid beverages diluted with nonpotable water (reconstituted fruit juices, ice, and milk) and foods washed in nonpotable water, such as salads. Other risky foods include raw or undercooked meat and seafood, and unpeeled raw fruits and vegetables. Safe beverages include those that are bottled and sealed, or carbonated. Boiled beverages and those appropriately treated with iodine or chlorine may also be safely consumed. Although food and water precautions continue to be recommended, travelers may not always be able to always adhere to the advice. Furthermore, many of the factors that ensure food safety, such as restaurant hygiene, are out of the traveler’s control.

 

References

  1. Steffen R. Epidemiology of travellers’ diarrhoea. Scand J Gastroenterol Suppl. 1983;84:5–17.
  2. Black RE. Epidemiology of travelers’ diarrhea and relative importance of various pathogens. Rev Infect Dis. 1990;12(Suppl 1):S73–9.
  3. Adachi JA, Jiang ZD, Mathewson JJ, et al. Enteroaggregative Escherichia coli as a major etiologic agent in traveler’s diarrhea in 3 regions of the world. Clin Infect Dis. 2001;32(12):1706–9.
  4. von Sonnenburg F, Tornieporth N, Waiyaki P, et al. Risk and aetiology of diarrhoea at various tourist destinations. Lancet. 2000;356(9224):133–4.
  5. Shlim DR. Update in traveler’s diarrhea. Infect Dis Clin North Am. 2005;19(1):137–49.
  6. DuPont HL, Ericsson CD. Prevention and treatment of traveler’s diarrhea. N Engl J Med. 1993;328(25):1821–7.
  7. Connor BA. Sequelae of traveler’s diarrhea: focus on postinfectious irritable bowel syndrome. Clin Infect Dis. 2005;41(Suppl 8):S577–86.
  8. Hoge CW, Gambel JM, Srijan A, et al. Trends in antimicrobial resistance among diarrheal pathogens isolated in Thailand over 15 years. Clin Infect Dis. 1998;26:341–5.
  9. DuPont HL, Jiang ZD, Ericsson CD, et al. Rifaximin versus ciprofloxacin for the treatment of traveler’s diarrhea: a randomized double blind clinical trial. Clin Infect Dis. 2001;33(11):1807–15.