Traveler’s Diarrhea

bacteriaTraveler’s diarrhea has been called by many names – in Mexico, Montezuma’s revenge, in India, Delhi belly, in Russia, the Trotskie’s, and in Africa, the Seeping Slickness.

As many as 25% of those traveling to high-risk areas develop a diarrheal illness. For the most part, this is a self-limited illness; however, 30% of sufferers are confined to bed, and a further 40% are forced to change their itinerary. This is not only a problem in developing countries. We have recently witnessed a number of serious incidents, such as the contamination of the town’s water supply with E.Coli 0157:H7 in Walkerton, Ontario, resulting in 7 deaths, and more than 2,000 sick, as well as a Cryptosporidium infestation of municipal drinking water in North Battleford, Saskatchewan, resulting in 3 deaths. These tragic events shook the foundations of Canadian government control over small, communal water systems, and serve as a reminder of the ever-present risk of exposure to contaminated water. We need to be vigilant; knowing how to identify and prevent problems, when traveling, can go a long way to enjoying one’s holiday.

While the general treatment of diarrhea is the same, regardless of the cause, it is important to understand how to deal appropriately with different situations, as well as to understand the rationale for the different treatments, which will be outlined.

There are both infectious and non-infectious causes of diarrhea; for the purposes of this presentation, we will deal only with the infectious causes, of which there are two broad categories resulting in acute adult diarrhea – community-acquired diarrhea, that is, diarrhea acquired in the community in which one normally lives (an example would be sick patients on antibiotics in hospital acquiring C. difficile infection), and traveler’s diarrhea, acquired during the course of travel.

Infectious diarrhea can be caused by bacteria, viruses, or parasites; the symptoms and treatments are different for each class of infectious agent. However, with all of them, you have to ingest organisms that have contaminated food, water or your fingers. It can be confusing to understand where the different organisms fit into this picture, so I thought it would be helpful to give you a brief description of the more common ones.

The commonest bacterial causes are E. Coli, Vibrio cholera, Salmonella, Shigella,Campylobacter, Clostridium, Difficile. The most common cause of traveler’s diarrhea is E.Coli.

Escherichia coli represents hundreds of strains of bacteria that are considered to be fecal coliform, coming from human or animal intestinal tracts. Ecoli 0157 represents one of the strains, which can cause severe illness; it is spread to humans by healthy cattle, in which this bacteria lives harmlessly; children under age 5 and the elderly are most susceptible. It is present in raw or rare ground meats (beef), or unpasteurized milk or apple cider; livestock manure infecting water sources can give rise to bloody diarrhea, and kidney failure through the production of a powerful toxin (Walkerton!).

Cholera is found in contaminated water or food; the risk is low for most travelers. High-risk groups are those providing disaster relief, or refugee camp workers; the best prevention is strict water and food precautions.

Salmonella is found in raw or undercooked meats, poultry, eggs, unpasteurized milk, alfalfa sprouts.

Typhoid fever, caused by S. typhii, is transmitted by contaminated food, water and also person-to-person contact by the fecal-oral route; it is a serious illness that can be fatal if untreated. Typhoid vaccine is recommended for those traveling in high-risk areas or if staying in rural areas.

Shigella results from fecal contamination of food by humans (lack of hand washing).

Campylobacter is found in animals and birds; it is commonly spread through direct contact with animals, particularly puppies, kittens and fowl; drinking unpasteurized milk, contaminated water, or eating undercooked poultry or meats are other sources of infection; also infection may occur from storing potentially hazardous foods at room temperatures.

Clostridium Difficile is found in the intestinal tract, and is one of the most common hospital infections, frequently related to antibiotic use; it releases toxins, which cause the diarrhea. Treatment is stopping the antibiotic.

The commonest viral agents are Norwalk, Herpes simplex, cytomegalovirus, adenovirus, and rotavirus. Viruses account for 30-40% of acute episodes, and are most often self-limited.

Norwalk is associated with outbreaks in nursing homes; it is also linked to banquets, cruise ships, swimming pools, schools, and restaurants. It is very contagious, and spreads by the fecal-oral route; shellfish and salad ingredients in contact with contaminated water, are the foods most often implicated. For you golfers in Ontario who wonder what happened to the watering stations on the golf courses, they have been removed because of a concern with this virus contaminating the water.

Herpes simplex is the virus responsible for cold sores, and genital sores; it may also give rise to diarrhea.

Cytomegalovirus is a member of the herpes virus group, and infects between 50-80% of adults by age 40. For most healthy persons, there are no symptoms and it’s not a serious problem; symptoms are similar to mononucleosis, with fever and mild hepatitis. It is most important in immuno-compromised individuals (following an organ transplant, HIV), pregnant mothers, and people working with children. The virus is shed in bodily fluids, and spreads easily in households or in day care centers.

Adenovirus affects children more than adults; it accounts for about 10% of all acute respiratory infections in children, so is frequent in day care centers and schools; it also causes episodes of diarrhea.

Rotavirus is the most common cause of diarrhea among children, resulting in the death of over 600,000 children annually worldwide! It is acquired through the ingestion of contaminated food or water, and is transmitted through the fecal-oral route; adults can be affected, although the disease is milder.

The commonest parasite infections are Giardia, Crytosporidium, Cyclospora, and Amebiasis.

Giardia, also known as ‘beaver fever’, in Canada, is found in humans and animals, particularly beaver, and is a common source of infection in my area in Canada (cottagers and canoe trippers). Diarrhea can become chronic; this parasite is usually spread through contaminated water, so a caution against drinking untreated surface water (lakes, streams, etc). It can be spread by infected individuals to others (e.g. daycare centers, where children have close contact with one another).
Cryptosporidium is usually contracted by drinking contaminated water, particularly water from surface sources (feces of infected animals).
Cyclospora is transmitted through infected feces by the fecal-oral route, and can then contaminate water or food.
Amebiasis (Entamaeba histolytica) results from the ingestion of fecally contaminated food or water; man is the only reservoir. It can be virulent in Mexico; most infected indigenous people have few if any symptoms; it can occur where human feces are used as fertilizer for crops!

Note: it is rare for travelers to acquire intestinal worm infections serious enough to cause symptoms; however, the same cannot be said of the indigenous population of most developing countries. This therefore is not a common reason for the development of traveler’s diarrhea.

Specific Food Hazards:

Water is easily contaminated because of either inadequate sanitation systems in many third world countries, or inadequate or improper management in developed countries (farm run-off contaminated with E.Coli, allowed to mix with drinking water in Walkerton!). As well, because of recurrent exposures, the locals have frequently developed an immunity to these organisms that we don’t possess. Note that ice does not kill viruses (hepatitis), bacteria (typhoid) or parasites (Giardia), so that ice cubes should be made from ‘clean’ water. Be cautious when drinking water found in pitchers in hotel rooms unless you have checked to make sure that it is ‘safe’.

Shellfish are natural reservoirs of bacteria and viruses because they filter large volumes of seawater.

Salads and uncooked fresh vegetables are risky because of the possibility of their contamination during transit, storage or preparation; be aware of the widespread use of human excrement (‘night soil’) as fertilizer in the tropics. Vegetables can be made safe if they are cooked and eaten hot.

Rice that has been reheated for use at another meal may be contaminated with bacteria, which multiply rapidly, if the rice is only warmed, and inadequately cooked.

Unpasteurized milk products (including yogurt and ice cream) may contain bacteria, which produce disease such as tuberculosis, brucellosis and toxoplasmosis; eating these products from street vendors can be risky.

Your own hands may be the source of food contamination. After a busy day of shopping at the tianguis, or Mercado, there is a significant chance that your hands will contain a multitude of organisms that are not ‘friendlies’.

Traveler’s diarrhea becomes significant when it lasts for more than 48 hours, and is associated with fever, dehydration, or blood or pus in the stool. Review of the literature reveals inconsistent and sometimes contradictory advice, confusion and controversy with regards to the management; what follows are the most recent recommendations.


Adopt the motto: ‘COOK IT, PEEL IT, or LEAVE IT’.

Good hand washing before eating is obviously very important.

The safest foods are those that are well cooked and eaten steaming hot. Remember, microwaving may not destroy bacteria. Any raw foods could be contaminated and are unsafe; avoid using leftovers – food spoils rapidly due to heat and humidity, and minimal contamination can lead to dangerous bacterial levels within a few hours. Note that re-heating food may not destroy certain heat-resistant toxins produced by bacteria, even though the bacteria may be killed by higher temperatures.

Fruits and vegetables, which you wash with safe water and peel yourself, are safe to eat. Avoid fresh fruit with broken skins. Watermelon and cantaloupe should be avoided because unsafe water is sometimes injected into them to make them weigh more.

Avoid ice cream, custards, meringues, unbaked pastries and soft cheeses. Avoid unpasteurized milk products (including yogurt and ice cream); milk may be boiled, although this destroys much of the protein. Powdered milk products are safe.

Avoid buffets, especially foods made with mayonnaise, cream or custard; also, cold buffets are risky if held on an open terrace, because of flies. This can be a tough one, as we’ve all eaten at salad bars! Be cautious! If it looks like the salads have been there for a while, you might want to pass on them!
Avoid raw, marinated or smoked fish, as they may contain parasites. Ceviche (marinated raw fish) has been associated with cholera outbreaks. Some species of fish and shellfish can contain a poison, even if well cooked (ciguatera).

Ciguatera is caused by eating fish which contain a toxin, produced by plants in some tropical waters; the toxin becomes more concentrated in larger fish, and there are no tests to detect the toxin; it is not destroyed by cooking or freezing. Symptoms include abdominal pain, nausea, vomiting, diarrhea, slow heart rate, numbness and tingling in the face and extremities, as well as severe itching, joint and muscle pain; symptoms last 2-3 weeks, but may persist for years.

So, don’t eat large predatory reef fish, such as grouper, snapper, jack, or barracuda. Eat fish in a reputable restaurant; avoid fish considered to be harmful by the local population.

Food Preparation: It is important to use safe water for drinking, washing fruit and vegetables, and in making ice cubes. Treatment with iodine products is preferable, as they are effective against bacteria, viruses and bacteria; chlorine products may not kill Giardia (beaver fever) – a parasite found all over the world.

Treating water. Drink only water that has been bottled, or boiled or disinfected with chlorine or iodine. If you choose to boil the water, it is sufficient to bring the water to a rolling boil, then cool and store it.
Our drinking water, at Birds, is first chlorinated in San Antonio, then, the potable water is directed through a reverse osmosis system (a water purification system that uses a semi-permeable membrane to allow purified water to pass through without allowing bacteria and contaminants to pass); finally, the water is treated with ultra violet light, at each building block.

There are a number of chemical products that are available locally – we have used Biopur, and Microbicida; these can be used for cleaning fresh fruit or vegetables, as per the instructions. There are a number of other products, which are essentially either iodine or chlorine-based; tincture of iodine 2.5%; 5 drops/liter, and let sit for 30 minutes; (if the water is cloudy, add 10 drops). Halzone tablets (chlorine) are available in Canada at pharmacies and sporting goods stores (for cottagers, canoe trippers). Household bleach (chlorine) 4-6% is also effective, although less reliable than iodine; use 2 drops/liter of clear water (4 drops/liter cloudy water).

Portable water filters consist of a fine filter, which removes bacteria and parasites; few, if any, have pore sizes small enough to keep out tiny virus particles, which produce hepatitis. Iodine is used to remove viruses; chemicals require a charcoal filter for removal.

I would recommend avoiding meals bought from street vendors, as the level of hygiene practiced in the preparation of the food is questionable at best; there is no point asking for problems!

These precautions become second nature after a while; I have to say, after all this, that we’ve really enjoyed our culinary experiences in Mexico, whether it’s trying out a new restaurant or checking out the mercado or tianguis for the best produce and best price! We appreciate being able to buy fresh produce, meat, fish, and enjoy the adventures of eating in Mexico. It’s impossible to follow all these guidelines all the time, and occasionally you have to make a judgment call that can prove to be an incorrect decision. However, we all need a heightened sense of awareness. These precautions and guidelines are applicable wherever you might be. BUEN PROVECHO!!

One can do everything wrong with respect to food and water, and still remain well. On the other hand, one can do everything right and develop diarrhea. Whether or not one stay healthy depends somewhat on the body’s defenses against infecting organisms and to a large extent on good luck!’ Remember that ‘travel expands the mind … and loosens the bowels!!’

The milder self-limiting diarrhea may not require any treatment. However, there are a number of things you can do at the outset to minimize symptoms. Self-medication, in otherwise healthy people, is safe. However, those with the following presentations require aggressive medical evaluation and monitoring: profuse watery diarrhea lasting more than 24-48 hours, diarrhea associated with fever higher than 38.5C (101.3F), severe abdominal pain, or blood or pus in the stool.

1. Anti-diarrheal drugs:
There are non-antibiotic products that are effective in reducing the frequency and intensity of the diarrhea.

Imodium (Loperamide 2mg) slows bowel contractions and reduces diarrhea without affecting the cause. Imodium is safe, and effective, with no abuse potential; it improves symptoms (cramps, urgency), and when used with antibiotics, significantly shortens diarrhea states. The dosage is two caps (4mg) to start, then one after each loose movement, up to a maximum of 8 caps daily. I would suggest Imodium to start, as it is a non-narcotic, and frequently quite effective.

Pepto-Bismol is more effective than Imodium for nausea, but less effective for diarrhea and cramps; it has an antibacterial effect, but does not reduce bowel motility; you can take two tabs (or 1 ounce) every ½ hour, up to 8 doses daily. Note that Pepto-Bismol contains salicylate (the component in Aspirin), and should be avoided by someone on blood thinners.

Lomotil 2.5mg tab, is also another agent, somewhat stronger than Imodium, that can be very helpful; it requires a prescription in Canada, but can be purchased, by requesting it at the pharmacy in Mexico. The recommended dosage is two tabs three to four times daily.

Probiotics, such as Lactobacillus acidophilus, found in yogurt, maintain or restore normal gut flora. There are two types of human bacteria – the ‘good’ or friendly types, and the ‘bad’ or harmful types. Each human requires about 85% of good bacteria to nourish the body and keep it healthy. Although the body is created with the proper ratio of good and bad bacteria, our modern lifestyle frequently alters this ratio; for example, antibiotics can kill both good and bad bacteria, allowing bad bacteria to multiply, disturbing the delicate balance. Other things like steroids, stress, an unhealthy diet, as well as toxins and proliferation of bad bacteria from contaminated food or water, can also disturb this balance. A prolonged episode of diarrhea can be helped by adding yogurt, or Lactobacillus, which can be purchased in capsule form, to your treatment regimen.

2. Rehydration
During a severe bout of diarrhea, you frequently not only feel unwell, you don’t feel like eating or drinking. It doesn’t take long to become dehydrated through the loss of fluids and electrolytes (sodium, chloride, potassium); it is important to replace these before this loss becomes problematic. If you want, you can prepare your own fluid replacement by following this rehydration formula;

Prepare two separate glasses of the following:

Glass number 1:
Orange, apple or other fruit juice (rich in potassium) = 8 ounces
Honey or corn syrup (glucose for absorption of necessary salts) = ½ teaspoon
Table salt (sodium and chloride) = 1 pinch

Glass number 2:
Water = 8 ounces
Baking soda (sodium bicarbonate) = ¼ teaspoon
Drink alternately from each glass until thirst is quenched; supplement as desired with carbonated beverages, water or tea.

There are also commercial rehydration formulas, such as Gastrolyte, which are expensive, and I believe, don’t usually warrant the cost in an otherwise healthy individual; frequently, if you are able to keep down fluids, sticking to clear fluids, no matter what kind (lemonade, herbal tea, fruit juices, soups), usually will work.

3 Diet
There is some controversy as to when to resume solid food; if the diarrhea is associated with nausea and vomiting, I would suggest staying on fluids only; otherwise resume eating solid food, guided by your appetite; start with small lighter meals. It is still recommended to restrict milk and dairy products for 1-2 weeks following a severe episode of diarrhea, because the enzyme that breaks down lactose is often diminished by damage to the bowel lining; milk or milk products are then not digested properly, giving rise to excessive gas, bloating and further diarrhea. Spicy foods, alcohol and caffeinated beverages are best avoided during the early convalescent period.

4. Antibiotics:
Community-acquired diarrhea is frequently viral, and so the routine use of antibiotics is not recommended. Traveler’s diarrhea, however, is frequently bacterial; the resulting illness can be severe and prolonged; the early use of antibiotics is now recommended!!

Quinlones are the empiric antibiotics of choice:

Cipro (Ciprofloxacin) 500mg twice daily for 2-3 days, depending on the severity; this can be safely combined with Loperamide.

Alternates are Noroxin (Norfloxacin) 400mg one daily or Septra (Trimethoprim/sulfamethoxazole) one double-strength, or two regular strength tabs daily.

My recommendation is to start with Imodium and Pepto Bismol on the first day, unless you also have a fever; if the diarrhea doesn’t seem to be improving by the second day you might consider adding the antibiotic. However, seek medical attention if there seems to be no improvement after 48 hours, and there is persistent, severe vomiting, dehydration, persistent fever, or blood in the stool.

Diarrhea persisting for longer than 7 days may be due to parasites, such as Giardia, amebiasis, or cryptosporidiosis, and will require evaluation by a health care professional.