When we are exposed to new bacteria that we are not familiar with, our bodies will tend to react badly. It is common that the new strains will act as pathological strains for us; this causes an infection known as gastroenteritis, commonly called the "stomach flu", "the trots", or just plain old diarrhea. This condition can quickly ruin an otherwise fantastic vacation. Interestingly traveler's diarrhea (TD) affects an estimated 20-50% of international travelers.

Signs and Symptoms
Most people are very aware of the moment that they have been affected by TD. By definition it requires three or more unformed stools in a 24hour period occurring in association with bloating, abdominal cramps, nausea, low-grade fever, urgency and fatigue. Symptoms can occur at any time during travel or even several weeks after returning home.

Pathogens Involved
The most common cause of TD is enterotoxigenic E. coli, and microbes account for around 80% of cases (the other 20% are viral). There are a number of other bacterial causes, and TD can even be caused by parasites such as Giardia and Cryptosporidium, although these tend to be the cases that appear weeks after infection.

Infection – How to Avoid It
The most common causes of infection are contaminated food or water, often caused by poor hand-washing techniques. The highest risk destinations include Latin America, Africa, Asia and the Middle East. When traveling to these destinations it is always a good idea to drink bottled water and be careful where you eat. Avoid ice, as it is likely made with local water. Try to eat cooked foods and avoid raw vegetable dishes, such as salad, which have the opportunity for contamination at a number of steps in the preparation process.

Why don't the locals get sick?
Interestingly, we all become accustomed to the bacteria in our surrounding environments. Our immune systems learn how to deal with them quickly and we develop an immunity, much like a constant vaccination. Research suggests that this type of adaptation takes anywhere from months to years to develop. So, the locals in your area of travel are well adapted to deal with any pathogens that they commonly encounter. When we travel, we enter regions where we are no longer familiar with the local flora and the new bacteria can cause negative effects.

Probiotics – Prevention and Treatment
Probiotics are a fantastic way of preventing infection and diarrhea while traveling. For these purposes, it's best to begin taking your probiotic for two weeks to a month before departure and then also throughout your stay. This allows you to build up the health of your gut flora, so that your friendly bacteria are at their strongest if you come into contact with pathogenic organisms. For more information on probiotics, please click here. If you do happen to pick up TD from drinking water or other sources, continue taking your probiotic for at least thirty days after your symptoms have abated to ensure that your intestinal flora has been completely replenished; it can take several weeks or even months for a full recuperation. One particular probiotic, S. boulardii, has been found in clinical trials to be useful both preventatively and as a treatment. For more information on S. boulardii, please click here.

Further Treatment
In addition to replenishing your gut flora, it is also very important to maintain your hydration. Diarrhea can quickly lead to dehydration and electrolyte imbalance. Getting sufficient electrolytes and drinking as much water as possible are both great strategies to prevent further problems. For more information on electrolytes, please click here. Most TD resolves within 3-5 days, so if your symptoms continue for longer than that time, it would be a good idea to seek medical attention. You should go sooner if you notice blood in your stool, as this can be a sign of a more severe condition. Using soluble fibre can significantly help to slow digestive motility and give you less time on the toilet. For more information on fibre, please click here. For more information on how to heal your gut after the diarrhea resolves, please see our digestive health article. Despite the temptation to run back to your vacation plans at the first sign of resolution, be sure to take the time you need to rest and heal. TD symptoms can take a toll on the body, so take that into account when you plan your next outing.