Traveler’s diarrhea (TD) as a syndrome in travelers was initially described more than 50 years ago. This was followed by the discovery of Escherichia coli (E. Coli) as the main culprit almost ten years later.
To this day, the risk of developing TD during a two week trip can be as high as 40% depending on destination and traveler characteristics.
Diarrheal disease is responsible for over a million deaths around the globe and is one of the five leading causes of mortality worldwide. This is a very common travel related illness and travelers need to be prepared to manage this illness that may occur during their trips overseas.
Risk factors can be broken down to environmental and the individual traveler factors.
The risk of TD depends not only on the destination and duration of exposure but also on the travel style. Particularly the available budget, that often determines where a traveler purchases meals.
Backpackers often favor street vendors, which are known to have a high risk of contaminated food.
However, the perceived quality of a hotel does not ensure protection from acquiring food borne illness. Studies of some 5-star hotels have found high TD rates, particularly following social events that serve buffet-style food exposed to warm environmental conditions.
Beach vacations are associated with lower rates of TD relative to travel for the purpose of visiting friends and relatives, multi-stop adventure tours, and ”all-inclusive” hotel arrangements.
Travelers on cruise vacations have a lower incidence of TD compared with those on land-based vacations. On the flip side, cruise ship passengers and staff are at risk of large outbreaks of norovirus that are difficult to contain once they have begun.
Decontamination of an entire ship after outbreaks is difficult if not impossible because of the large physical space that needs to be cleaned and decontaminated.
The virus is highly contagious and contact usually causes illness. To make matters worse, it is resistant to basic cleaning. Other outbreaks have also been seen in cruise ships when water is bunkered in foreign ports.
Although these outbreaks garner a great deal of media attention, the overall incidence of TD on cruise ships is declining.
Seasonal variations exist for the risk of traveler’s diarrhea, with lower rates occurring in winter. For example, in Mexico, the risk of TD increases with warmer temperatures and greater rainfall.
Exposure to recreational waters has been associated with several infections, including gastrointestinal tract infections, irrespective of preventive water treatment measures.
Individual traveler factors
Younger travelers tend to have a greater risk of acquiring TD. Infants and toddlers often having more severe disease and a greater propensity to require hospitalization.
Apart from being more adventurous, younger travelers may also eat more food, resulting in the ingestion of a larger inoculum of pathogens.
Numerous studies have shown that there is an equal incidence of traveler’s diarrhea between men and women. Women, being smarter than men, are more likely to seek medical care once they have TD.
Living in areas with high incidence of TD and chronic exposure to Escherichia coli can result in partial immunity. There is no difference in the incidence or duration of TD in travelers taking immunosuppressive agents.
Travelers with inflammatory bowel disease have a higher incidence of traveler’s diarrhea and longer duration of diarrhea and abdominal pain relative to others.
Prevention of Traveler’s Diarrhea
The advice to avoid potentially contaminated food and beverages by following the rule “boil it, cook it, peel it, or forget it” makes biological sense but often does not reduce the likelihood of getting TD.
Caution in food and beverage selection does not always mean you have a lower risk of TD and likely reflects sanitation practices at eating establishments that may not be apparent to the customer.
Enteropathogens are killed at 100°C and most food items served piping hot at 60°C are safe. However, foods are often not brought to an adequate temperature to kill pathogens.
Foods may have been left at a warm ambient temperature in a setting where there are neither screens at the windows to prevent the entry of flies nor sinks for employees to wash their hands after a visit to the toilet.
In some Mexican restaurants, both sauces and vegetables have been contaminated by pathogens. In Bangkok, touristy restaurants have been found to have enteric pathogens in cooked and raw foods.
Organisms in contaminated ice will survive concentrations of alcohol found in drinks mixed with hard alcohol.
Let’s be realistic, very few of us strictly adhere to all restrictive diet recommendations. It is unrealistic to rely entirely on a risk avoidance strategy. One of the many purposes of travel is to sample different foods.
Several antibiotic and nonantibiotic agents are available for prevention of traveler’s diarrhea.
Although the use of synbiotics, prebiotics, and probiotics to minimize the risk of development of traveler’s diarrhea is appealing because of their safety, the data supporting their use are not consistent.
Bismuth subsalicylate provides modest protection against TD. It is mostly marketed in North America and reduces the TD rate by 65% when given 4 times daily while traveling.
Bismuth subsalicylate adverse effects include turning the tongue and stools black. Because it contains salicylate, it should be avoided in patients taking anticoagulants or long term salicylate therapy.
Rifaximin is a poorly absorbed, gut-selective antibiotic. In several studies, rifaximin significantly reduced the incidence of TD.
Rifaximin is approved in more than 30 countries, including the United States, Canada, Australia, and some European countries, for treatment of traveler’s diarrhea caused by E coli infections.
Systemic antibiotics taken prophylactically can reduce the incidence of traveler’s diarrhea by more than 90%. However, antibiotic prophylaxis for TD is controversial and generally not recommended.
Antibiotic prophylaxis may be appropriate for high risk travelers who are prone to complications from diarrhea.
There is no vaccine that offers satisfactory protection against traveler’s di- arrhea. Typhoid vaccines are moderately effective against enteric fever caused by Salmonella enterica serotype Typhi, although this disease may not be associated with diarrhea.
The only commercially available cholera vaccine (not licensed in the United States) offers limited cross-protection. However, the estimated efficacy against TD from all causes is low.
Oral cholera vaccine for prevention of cholera can be considered for travelers who will be in areas of poor sanitation in cholera-endemic regions or where there is a current cholera outbreak.
Treatment of TD
Treatment is pretty simple. Volume, volume, volume. Keep yourself hydrated. It is probably a good idea to avoid alcohol, especially if you have severe TD as it can exacerbate the dehydration and cause other problems as well.
Adequate fluid and electrolyte replacement are essential to the management of TD. Antibiotics are not routinely recommended, but they do play a role in the treatment of bloody diarrhea.
In most cases, dehydration from TD can be effectively treated with oral intake. The recommendation from the World Health Organization (WHO) and The United Nations Children’s Fund (UNICEF) is oral rehydration salts (ORS) containing 75 mEq/L of sodium and 75 mmol/L of glucose.
Or if you have Gatorade, that will work just as well. A bland diet is probably best until you start feeling better.
The goal is to Keep hydrated, mitigate the symptoms of diarrhea such as abdominal pain, bloating and nausea and ultimately prevent any interruptions in your travel plans.
Loperamide can promptly decrease the number of loose stools when the traveler cannot accommodate frequent bowel movements.
Bismuth subsalicylate effectively controls nausea but takes longer to reduce diarrhea than loperamide.
Although probiotics may be helpful, their role in treating traveler’s diarrhea has not been established.
Antibiotics shorten the overall duration of moderate to severe traveler’s diarrhea to about a day and a half. The choice of the agent depends on the geographic location of the traveler and is not always indicated.
A combination of loperamide and an antibiotic can be taken when prompt reversal of symptoms is necessary.
TD, especially in resource-limited settings is very common. Poor sanitation is a major risk factor for the prevalence of diarrhea.
Adequate fluid and electrolyte replacement are the main treatment.
If diarrhea does not resolve, is so severe that you can’t keep yourself hydrated or you have bloody diarrhea, you should seek prompt medical evaluation as this may require antibiotic and intravenous fluid treatment.
Please remember that medical information provided by us must be considered an educational service only. This blog should not be relied upon as medical judgement and does not replace your physician’s independent judgement. This is NOT medical advice. Please seek the advice of your physician.