Travelers' diarrhea

"Montezuma's revenge" redirects here. For other uses, see Montezuma's revenge (disambiguation).

Travelers' diarrhea
Specialty	Infectious diseases

Traveler's diarrhea (in American English) or traveller's diarrhœa (in British English), abbreviated to TD, is the most common illness affecting travelers. Traveler's diarrhea is defined as three or more unformed stools in 24 hours in a traveler, commonly accompanied by abdominal cramps, nausea, and bloating.

Wilderness diarrhea (WD), also called wilderness-acquired diarrhea (WAD) or backcountry diarrhea, is the name preferred by some backpackers, hikers, campers and other outdoor recreationalists for traveler's diarrhea that appears in wilderness or "backcountry" situations while still in their home country. It is due to the same agents as all other traveler's diarrhea, which are usually bacterial and viral in short expeditions and may be giardiasis in longer expeditions. and is largely due to the absence of treated water and poor hygiene. Some people reserve the name backpacker's diarrhea as a synonym for giardiasis.

Most cases are self-limited and the pathogen is most often not identified.

Incidence

Each year 20%–50% of international travelers, an estimated 10 million people, develop diarrhea. TD is also known to mountaineers, as it can occur in camps due to poor sanitary conditions.

Risk factors

The primary source of infection is ingestion of fecally contaminated food or water.

The most important determinant of risk is the traveler's destination. High-risk destinations are the developing countries of Latin America, Africa, the Middle East, and Asia. Some first world countries are also deemed risky. A worldwide rating of drinking water safety is kept at Safe Water for International Travelers website.

Among backpackers, additional risk factors for this class of infections include drinking untreated surface water and failure by the individual and his or her companions to maintain personal hygiene practices and clean cookware. Campsites often have very primitive sanitation facilities, if any, making them as potentially dangerous as any third-world country.

People at particular high-risk include young adults, immunosuppressed persons, persons with inflammatory-bowel disease or diabetes, and persons taking H-2 blockers or antacids. Attack rates are similar for men and women.

Although traveler's diarrhea usually resolves within three to five days (mean duration: 3.6 days), in about 20 percent of persons the illness is severe enough to cause bed confinement and in 10 percent of cases the illness lasts more than one week.

For those who get serious infections, TD can occasionally be life-threatening. The serious infections include bacillary dysentery, amoebic dysentery, and cholera.

Symptoms

The onset of TD usually occurs within the first week of travel, but may occur at any time while traveling, and even after returning home. When it appears depends in part on the specific infectious agent. The incubation period for giardiasis averages about 14 days and that of cryptosporidiosis about seven days. Certain other bacterial and viral agents have shorter incubation periods, although hepatitis may take weeks to manifest itself. Most TD cases begin abruptly.

The illness usually results in increased frequency, volume, and weight of stool. Altered stool consistency also is common. Typically, a traveler experiences four to five loose or watery bowel movements each day. Other commonly associated symptoms are nausea, vomiting, diarrhea, abdominal cramping, bloating, low fever, urgency, and malaise, and appetite is usually low or non-existent.

It is much more serious if there is blood or mucus in the diarrhea, belly pain, or high fever. With serious cases of cholera, there is a rapid onset of symptoms, which include weakness, malaise (feeling rotten), and torrents of watery diarrhea with flecks of mucus (called "rice water" stools). Dehydration is a serious consequence, with death occurring in as quickly as 24 hours with cholera.

Causes

Infectious agents are the primary cause of travellers' diarrhea. Bacteria represent approximately 61% of the microorganisms responsible. Bacterial enteropathogens cause approximately 80% of cases.

The most common causative agent isolated in countries surveyed has been enterotoxigenic Escherichia coli (ETEC). Enteroaggregative E. coli is increasingly recognized and many studies do not look for this important bacterium. Shigella spp. are the other most common bacteria involved. Incidents in which other bacteria, such as Salmonella, Campylobacter, Yersinia, Aeromonas, and Plesiomonas spp., have caused diarrhea are isolated and occur less often. Protozoan parasites such as Giardia lamblia and Cryptosporidium may also cause diarrhea.

Some bacteria release toxins which bind to the intestines and cause diarrhea; others damage the intestines themselves by their direct presence. In infants and children, it is estimated that nearly 70% of diarrhea is due to viruses; for adult travelers, this drops to around 30%. Diarrhea caused by viral agents is usually self-limited.

Pathogens implicated in travellers' diarrhea are:

E. coli, enterotoxigenic	20-75%
E. coli, enteroaggregative	0-20%
E. coli, enteroinvasive	0-6%
Shigella spp	2-30%
Salmonella spp	0-33%
Campylobacter jejuni	3-17%
Vibrio parahemolyticus	0-31%
Aeromonas hydrophila	0-30%
Giardia lamblia	0 to less than 20%
Entameba histolytica	0-5%
Cryptosporidium sp	0 to less than 20%
Rotavirus	0-36%
Norwalk virus	0-10%

A sub-type of travelers' diarrhea afflicting hikers and campers, sometimes known as wilderness diarrhea, may have a somewhat different frequency distribution of pathogens.

Treatment

TD usually is a self-limited disorder and often resolves without specific treatment; however, oral rehydration therapy is often beneficial to replace lost fluids and electrolytes. Clear, disinfected water or other liquids are routinely recommended for adults. Water that is purified is best, along with oral rehydration salts to replenish lost electrolytes. Carbonated water (soda), which has been left out so that the carbonation fizz is gone, is useful if nothing else is available.

Travelers who develop three or more loose stools in a 24-hour period — especially if associated with nausea, vomiting, abdominal cramps, fever, or blood in stools — should be treated by a doctor and may benefit from antimicrobial therapy. Antibiotics usually are given for 3–5 days, but single dose azithromycin or levofloxacin have been used. If diarrhea persists despite therapy, travelers should be evaluated and treated for possible parasitic infection. There are different medications needed for bacterial dysentery, for amoebic dysentery, for giardia and for worms. There is no medication for Cryptosporidium, which can devastate people with AIDS. There can be 100% recovery from cholera when properly treated, which usually only means rehydration, usually through an intravenous line.

Antimotility agents

Antimotility agents (loperamide, diphenoxylate, and paregoric) primarily reduce diarrhea by slowing transit time in the gut, and, thus, allows more time for absorption. Some persons believe diarrhea is the body's defense mechanism to minimize contact time between gut pathogens and intestinal mucosa. In several studies, antimotility agents have been useful in treating travelers' diarrhea by decreasing the duration of diarrhea. However, these agents should never be used by persons with fever or bloody diarrhea, because they can increase the severity of disease by delaying clearance of causative organisms. Because antimotility agents are now available over the counter, their injudicious use is of concern. Adverse complications (toxic megacolon, sepsis, and disseminated intravascular coagulation) have been reported as a result of using these medications to treat diarrhea.

Prophylaxis

It is not recommended to take antimicrobial drugs to prevent TD, because they kill off beneficial bacteria and create resistant breeds of pathogenic (disease-causing) bacteria. Among the primary measures to prevent gastrointestinal illness are keeping good hygiene, getting specific vaccines and prophylactic medications. Studies show a decrease in the incidence of TD with use of bismuth subsalicylate and with use of antimicrobial chemoprophylaxis.

Dukoral has been shown to prevent TD and cholera - one dose a few weeks before travel, and another about a week before travel. Additionally, vaccine candidates are in various stages of development for enterotoxigenic E. coli, the leading cause of traveler's diarrhea, and Shigella.

Traveler's diarrhea is fundamentally a sanitation failure, leading to bacterial contamination of drinking water and food. It is best prevented through proper water quality management systems as found in responsible hotels and resorts. In the absence of that, the next best option for travelers is to take precautions to prevent the disease:

• Maintain good hygiene and only use safe water for drinking and teeth brushing.
• Use only safe bottled water and avoid ice. Reports of locals filling bottles with tap water, then sealing them and then selling the bottled water as purified water have come out of several countries.
• Drink safe beverages — these include bottled carbonated beverages, hot tea or coffee and water boiled or appropriately treated by the traveler.
• Active intervention involves boiling water for three to five minutes (depending on elevation), filtering water with appropriate filters or using chlorine bleach (2 drops per litre) or tincture of iodine (5 drops per litre) in the water. The wide availability of safe bottled water makes these interventions usually unnecessary for all but the most remote destinations.
• Avoid eating raw fruits and vegetables unless the traveler peels them.
• Recently an ultraviolet (UV) water purification device entered the market that allows people to quickly and conveniently treat small amounts of water, even in restaurant settings. The method of action is UV light bonding thymine rungs of the DNA molecule, destroying the organisms' ability to live or replicate. The major advantage (besides convenience) is that UV light also kills viruses when filtration does not. Many travelers are opting for this method because it adds no taste to the water, allows the drinking of cold water, and is extremely economical compared with the cost of buying bottled water.

If handled properly, well-cooked and packaged foods are usually safe. Eating raw or undercooked meat and seafood should be avoided. Unpasteurized milk, dairy products, mayonnaise and pastry icing are associated with increased risk for TD, as are foods or drinking beverages purchased from street vendors or other establishments where unhygienic conditions are present.

Several probiotics (Saccharomyces boulardii and a mixture of Lactobacillus acidophilus and Bifidobacterium bifidum) have significant efficacy. In a meta-analysis by McFarland (2005), no serious adverse reactions were reported in the 12 trials. Probiotics may offer a safe and effective method to prevent TD.

According to a study published in June, 2008, in the Lancet, researchers found that patients given a travelers’ diarrhea vaccine (made by the Iomai Corporation) were significantly less likely to suffer from clinically significant diarrhea than those who received a placebo. The study, which followed 170 healthy travelers ages 18-64 to Mexico and Guatemala, found that of the 59 individuals who received the new vaccine, only three suffered from moderate or severe diarrhea, while roughly two dozen of the 111 who received a placebo suffered from moderate or severe diarrhea. Only one of the 59 volunteers in the vaccine group reported severe diarrhea, compared with 12 in the placebo group.

Immunity

Travelers often get diarrhea from eating and drinking products that do not cause any problems to local people. This is due to immunity that is developed after repeated exposure to pathogens. It is not fully clear how much exposure is needed and up to what extent the immune system can deal with pathogens, but a study among expatriates in Nepal suggests that it can take seven years to develop immunity, presumably in the case of adults who mostly avoided exposure to pathogens. On the other hand, immunity that US-originated students acquired while living in Mexico appeared to disappear within as little as 8 weeks of non-exposure.

Colloquial names

There are a number of colloquialisms for travelers' diarrhea contracted in various localities, such as "Montezuma's revenge", "turistas", or "Aztec two step" for travelers' diarrhea contracted in Mexico, "Pharaoh's Revenge" in Egypt,"Delhi belly" in India, or "Bali Belly" in Bali. A recent local term in Pattaya, Thailand, is "Thai-dal wave", in Chile, although rare, it is called "Chilenitis".

Montezuma's revenge

Montezuma's revenge (var. Moctezuma's revenge) is the colloquial term for any cases of traveler's diarrhea contracted by tourists visiting Mexico. The name humorously refers to Moctezuma II (1466-1520), the Tlatoani (ruler) of the Aztec civilization who was defeated by Hernán Cortés the Spanish conquistador.

It is estimated that 40% of foreign traveler vacations in Mexico are disrupted by infection. Most cases are mild and resolve in a few days with no treatment. Severe or extended cases, however, may result in extensive fluid loss and/or dangerous electrolytic imbalance which pose a severe medical risk and may prove fatal if mismanaged. The oversight of a medical professional is advised.

Not all water supplies in Mexico are contaminated and many hotels have water purification systems that eliminate risk. Certain resort destinations also have large-scale water purification systems which provide safe water city-wide. Roadside and popular food stalls specifically should be avoided.

See also

• Gastroenteritis
• Travel medicine
• Wilderness diarrhea

References

 This article incorporates public domain material from websites or documents of the Centers for Disease Control and Prevention.