Acute diarrhea is the most common illness among travelers and therefore should be a concern for athletes who travel to various competitions. Over half of the people who travel from developed countries to developing countries are affected . Traveler's diarrhea (TD) is a common nuisance but is particularly distressing for athletes because it affects their performance. Although episodes of TD are nearly always benign and self-limited, the dehydration caused by diarrhea can be detrimental for athletes.
The classic presentation of TD is three or more unformed stools in 24 hours, as well as nausea, vomiting, fever, abdominal cramping, or bloody stools. Most cases occur within the first 2 weeks of travel and last approximately 4 days without treatment . TD should also be considered in athletes that develop diarrhea up to 10 days after they return home from traveling.
The most important determinant of risk for TD is the destination of travel. The Centers for Disease Control and Prevention (CDC) has divided regions of the world into three grades of risk: high, intermediate, and low [3••]. Low-risk countries include the United States, Canada, Australia, New Zealand, Japan, and countries in Northern and Western Europe. Intermediate-risk countries include those in Eastern Europe, South Africa, and some of the Caribbean islands. High-risk areas include most of Asia, the Middle East, Africa, and Central and South America.
TD is spread by food and water that is contaminated with fecal matter containing pathogens. The development of diarrhea is related to the number of ingested organisms that reach the intestine alive. Therefore, anything that helps the bacteria survive ingestion and transit to the intestine will increase the risk of developing diarrhea.
Unsafe foods and beverages include salads, unpeeled fruits, raw or poorly cooked meats and seafood, unpasteurized dairy products, and tap water. Food from street vendors , cold sauces, salsas, and reheated foods are risky and a common source of pathogens . Furthermore, athletes should be aware that food items on aircraft will often be prepared at the city of departure .
Diarrhea in travelers may be caused by a variety of bacterial, viral, and parasitic organisms (Table 1) . More than 90% of illnesses are caused by bacteria; the most common organism is Escherichia coli . Ingestion of a large amount of this organism is necessary to produce disease. This happens when there is a breakdown in sanitation, which is often the case in developing countries.
Other bacteria that cause the majority of TD include Salmonella species, Shigella species, Vibrio species, and Campylobacter jejuni. Campylobacter infections may be associated with bloody diarrhea as well as fever. Although Salmonella infections are frequently associated with food-borne outbreaks in industrialized countries, they are an infrequent cause of TD worldwide. Shigella infection may cause a bloody diarrhea with constitutional symptoms and fever.
Viral infections also cause morbidity for athletes and account for 5% to 10% of cases of TD. Outbreaks of Norwalk virus have been reported with a high percentage of susceptible athletes likely to become ill. This was the case in the Duke versus Florida State football game in 1998. In this event, a box lunch contaminated with Norwalk virus infected 62% of those who ate the lunch. There were 11 players on the opposing team that did not eat the box lunch but became ill because of the direct human transmission. It was therefore concluded that players with acute gastroenteritis should be excluded from playing contact sports .
Parasitic protozoan pathogens account for a small number of the cases of TD. Travelers often complain of persistent symptoms. The likelihood of finding a parasite rather than bacteria from stool specimens increases proportionately with the duration of symptoms. The most common organisms in this category include Giardia lamblia, Cryptosporidium parvum, Cyclospora cayetanensis, Entamoeba histolytica, and Dientamoeba fragilis .
Food poisoning should also be part of the differential diagnosis of TD. Gastroenteritis from preformed toxins (eg, Staphylococcus aureus, Bacillus cereus) is characterized by a short incubation period of 1 to 6 hours and usually resolves in less than 1 day.
Most episodes of TD occur within 4 and 14 days of the onset of travel , but can occur much sooner if the concentration of bacteria ingested is sufficiently high. The illness is generally self-limited with symptoms lasting for approximately 1 to 5 days. However, 8% to 15% of patients experience symptoms for more than 1 week and as many as 2% percent for more than 1 month .
The symptoms of TD depend upon the microorganism. The classic “turista” due to bacteria generally produces malaise, anorexia, and abdominal cramps followed by the sudden onset of watery diarrhea. Nausea, vomiting, and low-grade fever may occur, but typically there is not any blood or pus in the stool. Infections with C. jejuni and Shigella species may include symptoms of colitis, such as tenesmus, urgency, cramping, and bloody diarrhea. Belching and other upper intestinal symptoms are typical of giardiasis, whereas profuse watery diarrhea is characteristic of cryptosporidiosis and C. cayetanensis infection.
Because TD is generally self-limited, treatment is often initiated without identifying a particular organism. Routine stool cultures are rarely warranted, but a stool culture should be requested for patients with fever and colitis symptoms. Stool tests for G. lamblia and cyclospora should be performed in patients with predominantly upper gastrointestinal symptoms, such as bloating, gas, or nausea.
The essential treatment of TD is fluid replacement. TD usually causes volume depletion and fluids need to be replaced. The World Health Organization (WHO) recommends an oral rehydration solution (ORS) for severe fluid loss [3••]. ORS is a mixture of water, sodium chloride, potassium chloride, glucose, and sodium bicarbonate, and is available at pharmacies in most developing countries. Antibiotics and antimotility agents may be required, depending upon the circumstances . Most cases are self-limited and resolve on their own within 3 to 5 days of treatment with fluid replacement only. Antimicrobial therapy can shorten the disease duration to about 1 day.
The optimal diet for those with diarrhea is still controversial. A restricted diet beginning with only clear liquids to match diarrheal losses during the acute phase of diarrhea is often recommended. When antibiotic therapy is used, diet modification other than increased hydration is not likely to be important because disease duration is only about 1 to 2 days [14••].
Antibiotics are warranted to treat diarrhea in those who develop moderate to severe diarrhea as characterized by more than four unformed stools daily, fever, blood, pus, or mucus in the stool. In addition, some athletes desire antibiotic treatment for milder disease because diarrhea will affect their performance.
Antibiotic selection is based on the likelihood that an invasive organism is present and on antibiotic resistance patterns. Fluoroquinolones have been the drug of choice for TD in most parts of the world because of their efficacy against most enteropathogens. However, quinolones should be used with caution in athletes because of the increased risk of tendon rupture . Azithromycin is also an effective drug for the treatment of TD and has been shown to be equally effective as some fluoroquinolones . Because children are still developing their tendons and athletes are at risk for tendon injury, azithromycin is an excellent choice.
Rifaximin has become available for the treatment of noninvasive diarrhea caused by E. coli infection. For persons traveling to destinations where noninvasive E. coli is the predominant pathogen, such as Mexico, rifaximin is a good choice . Rifaximin is a nonabsorbed drug, has been demonstrated to be effective in the treatment of TD, and has equal efficacy to fluoroquinolones . Rifaximin use is becoming more common due to concerns about quinolone resistance. Rifaximin is not effective against infections associated with fever or blood in the stool, such as Campylobacter species [19•]. The absence of broad activity against the pathogens responsible for TD may limit its use.
Antibiotic resistance has developed among many routine enteric bacteria. Trimethoprim-sulfamethoxazole, ampicillin, and doxycycline are no longer recommended because of the development of widespread resistance .
The most common parasitic cause of TD is G. lamblia infection, and can be treated with metronidazole, tinidazole, or nitazoxanide. Cyclosporiasis is treated with trimethoprim-sulfamethoxazole and amebiasis is treated with metronidazole or tinidazole, followed by treatment with a luminal agent such as iodoquinol or paromomycin.
Bismuth subsalicylate can also be used to treat diarrhea, although large doses are required. This medicine has both antisecretory and antimicrobial properties, but it can potentially cause salicylate toxicity (Table 2) .
Antimotility agents such as loperamide and diphenoxylate are frequently used by travelers to reduce the rate of stooling, but they do not treat the cause of diarrhea. The use of loperamide in TD has been controversial because of concerns about prolonging illness, but it is now considered safe when combined with an antibiotic . A conservative approach would be to use loperamide for TD only if combined with an antibiotic and if the traveler has a long trip or will have no toilet access, or during a sports event.
Particular vigilance about hydration is important since the antimotility drugs do not kill the pathogen causing the diarrhea or stop the secretory process in the intestine. Athletes may be unaware of how much fluid they are losing into their intestine because they no longer have frequent bowel movements. Antimotility agents should be stopped if abdominal pain or other symptoms worsen or if the diarrhea continues to be intractable after 2 days.
There are several ways by which athletes can reduce their risk of developing traveler's diarrhea . Avoiding high-risk foods and adventuresome eating behaviors may reduce the amount of ingested pathogens. Freezing does not kill the organisms that cause diarrhea and therefore ice in drinks is not safe unless made from adequately boiled or filtered water. Also, alcohol does not sterilize water or ice and so mixed drinks may still be contaminated.
In addition, fruit salads and lettuce are examples of unwise food choices because the ingredients may have been improperly washed and may have been sitting for prolonged periods without refrigeration. Furthermore, condiments frequently become contaminated . Bottled drinks should be requested without ice. Fruits that can be peeled are safe as long as they are peeled just prior to eating.
Both antibiotics and certain other drugs have been evaluated for the prevention of TD. Antibiotic prophylaxis is usually not recommended by the CDC because it can lead to drug-resistant organisms and may give travelers a false sense of security. Prophylactic antibiotics are effective in preventing the majority of diarrheal disease in travelers, but cannot be recommended unless the complications of diarrhea or an underlying medical condition make the consequence of dehydration so severe that the benefits of using antibiotic prophylaxis outweigh the risks .
If prophylactic antibiotics are indicated, rifaximin is the preferred antibiotic because it is not absorbed and is well tolerated. Concerns regarding the development of fluoroquinolone resistance have led to increased interest in the use of rifaximin.
Nonantibiotic preventive methods have also been studied. Bismuth subsalicylate can prevent a significant number of cases of TD . However, the doses required make this inconvenient for the traveler, and the same cautions about salicylate toxicity apply when used for prevention as well as therapy. Bismuth subsalicylate provides a rate of protection of about 60% against traveler's diarrhea .
Probiotics such as Lactobacillus species have been shown to decrease the incidence of diarrhea in travelers . Probiotics are a more natural approach to prophylaxis of TD. Probiotics colonize the gastrointestinal tract and theoretically prevent pathogenic organisms from infecting the gut .
Acute diarrhea is the most common illness among travelers and should be a concern for athletes traveling to various competitions. Because athletes travel to competitions all over the world, sports medicine providers need to be able to diagnose and treat gastrointestinal infections.
TD is a self-limited condition caused by bacteria, viruses, or parasites, but it is uncommon to have to make an etiologic diagnosis. Stool cultures or examination for ova and parasites should generally be reserved for cases that last beyond 10 to 14 days, except for patients with fever and colitis in immunocompromised patients or in those with upper intestinal symptoms in whom giardiasis is more likely.
The mainstay of therapy for TD is fluid replacement. Athletes could be given a prescription for antibiotics to fill and take with them in case diarrhea develops. Antibiotics should be taken if unformed stools occur more than four times a day or for fever, blood, pus, or mucous in stools. Prophylactic antibiotics may be considered for short-term travelers who are high-risk hosts or are taking critical trips during which even a short bout of diarrhea could be devastating to their performance [3••].
Antimotility agents are usually not necessary for mild to moderate diarrhea and should not be used except for severe diarrhea in association with antibiotic therapy. These agents should be discontinued if abdominal pain develops, other symptoms worsen, or diarrhea persists.
Attention to food and drink choices, water purification, and antibiotic prophylaxis are all means of attempting to prevent TD. Antibiotic prophylaxis is usually reserved for patients in whom dehydration would put them at severe risk.
References and Recommended Reading
Papers of particular interest, published recently, have been highlighted as: • Of importance •• Of major importance
1. von Sonnenburg F, Tornieporth N, Waiyaki P, et al.
: Risk and aetiology of diarrhoea at various tourist destinations. Lancet
2. Hill DR: Occurrence and self-treatment of diarrhea in a large cohort of Americans traveling to developing countries. Am J Trop Med Hyg
3.•• Centers for Disease Control and Prevention: Traveler's diarrhea.
This is a great resource for up-to-date information for traveling.
4. Ansdell VE, Ericsson CD: Prevention and empiric treatment of traveler's diarrhea. Med Clin North Am
5. Adachi JA, Mathewson JJ, Jiang ZD, et al.
: Enteric pathogens in Mexican sauces of popular restaurants in Guadalajara, Mexico, and Houston, Texas. Ann Intern Med
6. Centers for Disease Control. Shigellosis related to an airplane meal - Northeastern US. MMWR Morb Mortal Wkly Rep
7. Steffen R: Epidemiologic studies of travelers' diarrhea, severe gastrointestinal infections and cholera. Rev Infect Dis
8. DuPont HL, Ericsson CD: Prevention and treatment of travelers' diarrhea. N Engl J Med
9. Becker KM, Moe CL, Southwick KL, MacCormack JN: Transmission of Norwalk virus during football game. N Engl J Med
10. Goodgame R: Emerging causes of traveler's diarrhea: Cryptosporidium, Cyclospora, Isospora, and Microsporidia. Curr Infect Dis Rep
11. Steffen R, Collard F, Tornieporth N, et al.
: Epidemiology, etiology, and impact of traveler's diarrhea in Jamaica. JAMA
12. Rendi-Wagner P, Kollaritsch H: Drug prophylaxis for travelers' diarrhea. Clin Infect Dis
13. Carpenter CC, Greenough WB, Pierce NF: Oral-rehydration therapy: The role of polymeric substrates. N Engl J Med
14.•• Huang DB, Awasthi M, Le BM, et al.
: The role of diet in the treatment of travelers' diarrhea: a pilot study. Clin Infect Dis
Well-conducted pilot study showing that diet restriction during treatment of TD is not associated with improvement of clinical symptoms.
15. Seeger JD, West WA, Fife D, et al.
: Achilles tendon rupture and its association with fluoroquinolone antibiotics and other potential risk factors in a managed care population. Pharmacoepidemiol Drug Saf
16. Adachi JA, Ericsson CD, Jiang ZD, et al.
: Azithromycin found to be comparable to levofloxacin for the treatment of US travelers with acute diarrhea acquired in Mexico. Clin Infect Dis
17. Steffen R, Sack DA, Riopel L, et al.
: Therapy of travelers' diarrhea with rifaximin on various continents. Am J Gastroenterol
18. 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
19.• Adachi JA, DuPont HL: Rifaximin: a novel nonabsorbed rifamycin for gastrointestinal disorders. Clin Infect Dis
Great review article explaining mechanism of action, pharmacokinetics, efficacy, and safety profile of rifaximin.
20. Murray BE: Resistance of Shigella, Salmonella, and other selected enteric pathogens to antimicrobial agents. Rev Infect Dis
21. Gilbert DN, Moellering RC, Eliopoulus GM, et al.
: The Sanford Guide to Antimicrobial Therapy. Sperryville, VA: Antimicrobial Therapy; 2006.
22. Murphy GS, Bodhidatta L, Echeverria P, et al.
: Ciprofloxacin and loperamide in the treatment of bacillary dysentery. Ann Intern Med
23. Ericsson CD, Pickering LK, Sullivan P, et al.
: Role of location of food consumption in the prevention of travelers' diarrhea in Mexico. Gastroenterology
24. Steffen R, Heusser R, DuPont HL: Prevention of travelers' diarrhea by nonantibiotic drugs. Rev Infect Dis
1986, 8(Suppl 2)
25. Hilton E, Kolakowski P, Singer C, Smith M: Efficacy of Lactobacillus GG as a diarrheal preventive in travelers. J Travel Med
26. Oksanen PJ, Salminen S, Saxelin M, et al.
: Prevention of travellers' diarrhoea by Lactobacillus GG. Ann Med