Everything you need to know about Traveler’s Diarrhea
By Dr. Jun R. Ruiz
Imagine yourself in your dream destination, with your loved ones, and enjoying the time of your life. Everything in your trip is unraveling wonderfully as planned, as you have spent the last few months organizing and preparing for this once-in-a-lifetime adventure.
You are making friends with wonderful people of diverse backgrounds from all over the world, and your tour guide is providing you with a plethora of interesting information on the history, culture, and several tourist attractions.
Suddenly, something explosive is about to happen and threatens your vacation. Diarrhea strikes, and you just have entered the realm of traveler’s diarrhea. Though it is usually mild in most of the cases, this type of diarrhea can restrict your fun in your scheduled long list of activities.
Traveler’s diarrhea is defined as “the passage of 3 or more sudden onset of unformed (abnormally loose or liquid) stools per day with one or more associated enteric symptoms occurring in the traveler after arrival.” The keywords in the definition are frequency (of at least three times) and the consistency of the stool after arrival.
It is the most common travel-associated disease, and it is transmitted through the fecaloral route in contaminated food and water. It is caused by a variety of bacteria, viruses, and protozoans. The highest rates occur in travelers to Africa, and Asia (South, Central and West Asian countries). 25 – 50 percent of travelers develop diarrhea in their first two weeks of travel.
Traveler’s diarrhea was previously classified based on the number of bowel movements per day. The latest guidelines now classify the disease based on its functional impact on the patient for severity.
• Mild: diarrhea that is tolerable, non-distressing, and doesn’t interfere with planned activities.
• Moderate: diarrhea that is distressing or interferes with planned activities.
• Severe: diarrhea that is incapacitating or completely prevents planned activities.
• Persistent: diarrhea lasting more than two weeks.
There are several risk factors for traveler’s diarrhea. These can be categorized, either as host-related factors, or travel-related factors. The country of origin and age are host-related, while the destination and duration of stay are travel-related.
Tourists from developed countries are at a higher risk for traveler’s diarrhea than those from developing countries. This highlights the role of acquired immunity protection against pathogens in the digestive tract in people who live in developing countries, who are exposed constantly to these pathogens growing up. Thus, the risk for traveler’s diarrhea in Americans visiting Southeast Asia is higher, compared to Filipinos tourists traveling to the United States.
The risk is also highest in younger groups, especially those in their twenties, due to risky behavior and adventurous travel, and not related to immune status. Backpackers have a higher risk due to higher environmental risks they encounter.
The travel destination is the single most important risk factor for traveler’s diarrhea. The countries of the world are divided into three risk categories (See Figure 1). Most of the developed countries, like the United States, Northern Europe, Japan, and Australia are in the Low-Risk category, with <8 percent risk during a two-week stay. Those countries that are considered as Intermediate-Risk include Southern and Eastern Europe, Russia, and China.
The rest of the world, like the Philippines and most the Asian continent, and as well as Africa are in the High-Risk category, with a risk of >20 percent. However, the degree of danger to the disease is not absolute, as the risk can vary within region, within the country, and even between hotels in the city.
The risk is highest during the first week of travel. Other risk factors include immunocompromised conditions, like those afflicted with the Human Immunodeficiency Virus (HIV), and patients on acid-suppressive medicines (proton-pump inhibitors, like omeprazole). The gastric acid serves as a barrier against enteric pathogens, and this protective acid is reduced in patients taking these medications.
An infectious pathogen can be identified in 60-80 percent of those afflicted with traveler’s diarrhea. The majority (50-80 percent) are caused by bacteria and its toxins. Escherichia coli is the most common culprit, but Campylobacter is the most prevalent agent in Southeast Asia. The non-bacterial causes of traveler’s diarrhea are viruses and protozoans. Occasionally, no pathogen is found despite an extensive workup.
Ninety percent of affected persons have acute watery diarrhea. The symptoms occur in the first 4-7 days after arrival. Most patients report between four to seven bowel movements per day. Those who have invasive infection (seen in 10-20 percent of patients) will present with fever and bloody diarrhea. Afflicted patients can also have nausea, vomiting, abdominal pain, tenesmus, and even non-gastrointestinal complaints. Some persons report incapacitation for at least a day.
The median duration of symptoms is three days. Fortunately, symptoms are usually mild. The classic traveler’s diarrhea typically resolves without complication. Because it is self-limiting, detailed laboratory and diagnostic investigations are unnecessary and not cost-effective.
Food and hygiene measures
Food and water have been implicated as source for traveler’s diarrhea. Bacteria can survive in food, if not heated up to 60 degrees. As traveler’s diarrhea is caused by ingestion of contaminated food and water, counseling on food and water hygiene is an important tool on preventing the disease.
Do not eat raw or undercooked meat and seafood. Avoid ground-grown leafy vegetables and fruits as the unwashed pieces can be contaminated with bacteria. Street food is a common source of this diarrhea, unless it is served piping hot. Bottled beverages are safe, but not tap water and ice cubes from unreliable sources.
Frequent handwashing with soap decreases the incidence of diarrhea. ‘Boil it, cook it, peel it, or forget it’ remains the standard preventive advice.
However, hygiene measures alone appear to be less effective as presumed. The Infectious Disease Society of America continues to advocate public education on these hygienic measures. The fact that we are unable to reduce traveler’s diarrhea on lifestyle modifications alone has led to the use of antibiotics as prophylaxis in the past during high-risk periods of travel.
The latest guidelines on traveler’s diarrhea were published by The International Society of Travel Medicine in the Journal of Travel Medicine last year. They are clear that antimicrobial prophylaxis should not be used routinely in travelers. It can be considered for travelers at high risk of health-related complications, like those with HIV and Inflammatory Bowel Disease. The drugs used in prophylaxis are rifaximin, azithromycin, and bismuth subsalicylate (not available in the Philippines).
Just like any other diarrhea, oral rehydration therapy, consisting of clean water and WHO-oral rehydration solutions (brands like Hydrite, Glucolyte Plus, Oralite),should be given. Loperamide is the most widely used drug in traveler’s diarrhea. It provides rapid symptom improvement in diarrhea. It is fast-acting, safe, and well-tolerated.
Early and rapid initiation of antibiotics reduces the duration of illness. The three most commonly used effective anti-bacterial drugs are quinolones, rifaximin, and azithromycin (See Table 1).
Ciprofloxacin is the most commonly used quinolone, and it was previously considered the firstline therapy for bacterial pathogens in traveler’s diarrhea. Quinolones effectively prevent enteric infection by diarrheagenic E. coli and many of the invasive pathogens encountered by travelers. However, these are not effective for Campylobacter and resistant E. coli in in India and Southeast Asia. Quinolones are not recommended in pregnancy.
Azithromycin is effective against bacterial pathogens that cause dysentery, including fluoroquinolone-resistant Campylobacter and Shigella, especially in Southeast Asia. It is safe for children and in pregnancy.
Rifaximin is a non-absorbed antibiotic. It is recommended for treatment of non-febrile and non-dysenteric traveler’s diarrhea, predominantly against E. coli. It is comparable to ciprofloxacin in efficacy against E. coli, but is not effective against Campylobacter and enteroinvasive organisms. The drug has a good safety profile.
Self-treatment with antibiotics will improve illness within one to one and-a-half day, shortening the overall duration by 1 to 2 days. The antibiotic treatment of choice depends on the prevalence of the type of bacteria in the travel destination. Fluoroquinolones are the drugs of choice in Mexico, Central America, sub-Saharan Africa, and possibly South America, where resistant Campylobacter is not likely to predominate. In South and Southeast Asia where Campylobacter is a higher risk, azithromycin is the first line.
Guidelines on treatment based on severity
In mild traveler’s diarrhea, antibiotic treatment is not recommended in patients. Loperamide may be considered for symptom relief. The traveler is encouraged to use supportive measures to prevent dehydration.
In moderate traveler’s diarrhea, antibiotics may be used. Fluoroquinolones, azithromycin, and rifaximin may be used, depending on the region. Loperamide is used as adjunctive therapy.
In severe traveler’s diarrhea, antibiotics should be used. Azithromycin is preferred to treat severe cases. Fluoroquinolones and rifaximin may be used to treat severe, non-dysenteric traveler’s diarrhea.
Probiotics are dietary supplements of living bacteria or yeast providing health benefits. However, there is insufficient evidence to recommend the use of commercially available probiotics to prevent or treat traveler’s diarrhea.
Persistent diarrhea is diarrhea persisting for more than 14 days after travel. Microbiologic testing is recommended in returning travelers with severe or persistent symptoms or in those who fail empiric therapy.
Some patients who had traveler’s diarrhea may develop persistent abdominal symptoms suggestive of Post-Infectious Irritable Bowel Syndrome, despite clearance of the infectious agent. This is believed to be a dysfunction of the brain-gut axis, where there is a new hypersensitivity of the gut.
As there are no travel clinics in the Philippines, unlike in the United States, it may be beneficial for a traveler here to consult first with a physician who is knowledgeable with travel-related conditions before embarking on his journey. It is better to be equipped with the knowledge on how to prevent and handle the common travel-related illnesses, as there may be no doctor in the house when it strikes. As you work hard to achieve your dream vacation, you deserve to be in near-perfect physical state and frame of mind while in utopia.
Sept 2018 Health and Lifestyle