Adventure Doc: Travel and Expedition Medicine Blog

Basics:  Known around the world by many names including Montezuma’s revenge, Delhi belly and mummy tummy, traveler’s diarrhea (TD) is the most common illness travelers face.  Nothing can slow down a fun trip like TD and this can also have serious health implications.  Staying hydrated is the most important method to avoid serious problems and recognizing warning signs such as blood in the stool, fevers or abdominal cramping can help a savvy traveler know when to seek medical help.  Bacterial infections are the most common cause travelers face.  Typical durations of TD are 4-6 days and 90% of cases occur within the first two weeks of travel .    

Symptoms:  TD has many definitions but the presence of three or more loose-formed stools in one day is a good place to start.  Abdominal cramping, nausea and vomiting and fevers can also occur.  The presence of blood in the stool can indicate the infection has the ability to directly damage the intestinal wall and should be taken seriously. 

Diagnosis:  Diagnosing TD is largely based on symptoms.  The presence of blood in the stool can indicate that there is an invasive process damaging the intestinal lining.  This should be taken seriously.  Diarrhea with fevers and severe abdominal cramping can also signal a more serious illness and should prompt one to seek medical care.

Anatomy:  The Gastrointestinal tract starts at the mouth and ends at the anus.   As food enters the mouth, it passes down the esophagus to the stomach where it sits for approximately 45 minutes.  After being broken down by gastric secretions, the food matter then heads to the small intestine (duodenum, jejunum, and ileum).  The small intestine is the site where most nutrients are absorbed by the body, across the intestinal wall.  From the small intestine, the food matter begins to look more like feces as it progresses to the large intestine or colon.  The colon serves to absorb water from the food material before is passes through the anus and out of the body as feces.

Care/Treatment:  The most important treatment for traveler’s diarrhea is to ensure adequate hydration.  Dehydration is very common in those who suffer from TD due to the large amounts water being lost from the body in the loose stools.  Oral rehydration with sports drinks and clean, pure water should be started the moment diarrhea strikes.  Depending on the causes of the diarrhea, antibiotics may be required to kill bacteria or parasites.  Using anti-diarrheal medications to prevent frequent trips to the toilet have a role, but should be used with caution.  Preventing the infectious diarrhea from leaving your body may trap the bacteria or parasite in the intestines, giving it more time to do damage.  Try to ensure you know the cause of the diarrhea before stopping it with anti-diarrheal medications.

Symptoms continued:  Typical traveler’s diarrhea is loose and watery.  Some doctors advise a “let it flow” approach due to the fact that diarrhea is the body’s way of excreting the infectious agent that causes the symptoms.  While being a very inconvenient way to deal with diarrhea, this is generally a good approach providing there are no warning signs indicating a more serious infection and the person continues to drink large amounts of fluids.  Warning signs of a serious diarrheal infection include the presence of fevers, blood in the stool and severe abdominal cramping.  Perhaps the most serious of these signs is blood.  This indicates that the lining of the intestines is being damaged or penetrated by the causative agent.  Anytime the intestinal lining is being compromised, the possibility of a systemic infection occurs.  Should a traveler suffer from bloody diarrhea, a visit to a health care provider is advised.  This type of diarrhea typically requires antibiotics and may even require further tests to determine the exact cause of the diarrhea.

Diagnosis and Causes:  The most common cause of traveler’s diarrhea is a gram-negative bacterium called enterotoxic Escherichia Coli (E. Coli or ETEC).  This bacterium has been implicated in up to 70% of traveler’s diarrhea, worldwide .

Campylobacter species, specifically C. Jejuni is considered the second most common cause (30%)  and appears to have seasonal peaks.  For example, in USA C. Jejuni peaks in the summer months while in Northern Africa, the drier, winter months see more cases. 

There are a multitude of bacterial causes for traveler’s diarrhea and while not as common as E. Coli, they deserved to be mentioned.  Salmonella, Shigella, Vibrio species (V. cholera, V. paraheamolyticus and Yersinia enterocolitica are all known causes of TD occurring in roughly 0-15% of cases . 

Viral infections are estimated to cause 20% of TD cases in adults  with the Norwalk virus being a common agent, especially on cruise ships.  Rota Virus, Hepatitis A and E can also cause diarrhea in travelers.  Rota Virus is more likely seen in pediatric patients than adults. 

Parasitic infections can be causes of traveler’s diarrhea and protozoan infections are considered most common.  Giardia lamblia, Cryptosporidium, Cyclospora, Entamoeba and Isospora species are implicated in roughly 5% of TD cases .   

Less common causes of traveler’s diarrhea can include helminth infections, food poisonings and seafood toxidromes.

           
Diarrhea Evaluation in the Returned Traveler:  Further studies into the etiology of the traveler’s diarrhea starts with thorough travel history, focusing on destinations and eating habits/history.  The majority of classical TD cases occur within the first 1-2 weeks of travel and last 4-6 days.  Thus, a typical traveler with complaints of diarrhea upon return to home will likely be suffering from recurrent or prolonged diarrhea.  Only 5-10% of travelers have TD symptoms longer than 2 weeks . 

Initial laboratory investigations into diarrhea in a traveler should include electrolyte panels and stool studies looking at the presence of fecal red blood cells, white blood cells, ova and parasitic studies and a bacterial culture.  A Wright’s stain for fecal leukocytes has 82% sensitivity and 83% specificity for presence of invasive bacterial pathogens, although some clinicians feel this test is no longer useful due to cost and labor .  The rational is to limit this test for severely dehydrated, immunocompromised, toxic appearing patients.  

Anatomy and Diet:  Knowledge of the intestinal anatomy and physiology is key to understand proper dietary modifications and treatment for those effected by traveler’s diarrhea.  The inner lining of the intestinal wall on the small intestines is lined with a brush border that contains enzymes to assist in food digestion.  The specific enzyme (lactase) that breaks down lactose (found in dairy products) is the concern and can be particularly fragile.  When someone suffers from diarrhea, this brush border containing lactase is frequently damaged and excreted with the diarrhea.  This person is now without the ability to digest lactose as effectively as they did before their diarrheal illness.  Thus, the bits of food containing lactose in their intestines go undigested and can act as an osmotic attractant to the water in their body.  Basically, the undigested bits of dairy food (cheese, milk, etc) actually draw more water into the intestine, causing more diarrhea and water loss.  Avoidance of dairy products during diarrheal illnesses should be considered for this reason.  After a few days to 1 week of no symptoms, the brush border typically re-grows to the level it was at before the diarrhea.

Prevention of Traveler’s Diarrhea:  Prevention of TD centers around three methods: dietary safety, immunizations and chemoprophylaxis (medications taken to prevent diarrhea).
 
Education on safe eating practices should form the basis of protection.  Hand washing before meals should become second nature.  Avoid eating at locations that look dirty or if the chef has a sore on their hand.  Ensure your food is properly cooked and drink only from clean and purified water sources.  Bottled water is good but poured over ice made from contaminated water does not help you avoid illness. 
The Travel and Tropical Medicine Manual advises these 10 rules for selection of safe food and water:
1) Drink purified water or bottled carbonated water
2) Eat foods that are thoroughly cooked and served piping hot
3) Eat fruits that have thick skins and these should be peeled at the table by the traveler
4) Avoid salads that include raw vegetables, especially green leafy vegetables
5) Do not use ice cubes in any beverages, including alcoholic beverages
6) Only eat and drink dairy products made from pasteurized milk
7) Avoid shellfish and raw or undercooked seafood, even if “preserved” with lime/lemon juice or vinegar
8) Do not buy and eat food sold by street vendors
9) If canned beverages are cooled by submersion of the can in a bucket of ice water or stream, be sure to dry off the outside of the can prior to drinking
10) Use purified water for brushing teeth and taking medications

I have to admit that I do not always follow all of these rules.  I am what expedition doctors call an “adventurous eater” and am considered higher risk for acquiring TD because of these actions.  Sticking to these rules can go along way in preventing traveler’s diarrhea.

Immunizations to prevent traveler’s diarrhea:  Few vaccines exist to prevent TD.  Some to consider include the vaccine against Hepatitis A and the typhoid vaccine, both of which are very effective at preventing those specific causes of TD.  There is also a vaccine against Cholera, which is not very effective.

Chemoprophylaxis to prevent traveler’s diarrhea:  Taking medicine to prevent TD is not necessarily for every traveler, for a variety of reasons.  Should you be considering this regime, speak with your personal travel health provider before your trip.  Conditions and travelers who may benefit from such prophylaxis include those on honeymoon, business travelers, athletes and travelers with prior chronic medical conditions.  Generally, travelers should be encouraged to carry antibiotics to treat TD once acquired rather than taking a daily medication to prevent illness.  Common routines can include:

Bismuth-Subsalicylate(Pepto-Bismol)
2 tablets or 60mL solution taken every 6 hours
Studies have shown this to be less effective than antibiotics; not for use by those with aspirin allergies, those taking other salicylate medicines, pregnant travelers or children.  Frequent doses and large numbers of tablets required to be packed may effect compliance.

trimethoprim160mg/sulfamethoxazole 800mg(Bactrim, Septra)
One tablet daily
Not to be used by those with sulfa allergy, may be ineffective in some parts of the world due to bacterial drug resistance

Doxycycline 100mg
One tablet daily
Not for use by pregnant travelers, children under age 8 years.  May cause vaginal yeast infections and increased sun sensitivity.

Ciprofloxacin 500mg
One tablet daily
Not for use by pregnant travelers, children under age 18 years and those with allergies to quinolone antibiotics.  Some drug-drug interactions are possible, especially with caffeine

Probiotics
Saccharomyces boulardii and  Lactobacillus species have been shown to decrease rates of TD by approximately 8% .  This appeared more effective in children than adults and in decreasing diarrhea rates in those already taking antibiotics.  Further studies need to be done to clearly note efficacy for use in TD prevention. 

Treatment of Travelers Diarrhea Symptoms:  Treatment of TD typically centers on rehydration, lessening diarrheal symptoms and antibiotic medication.  Self-treatment of TD is simply the traveler getting a prescription of antibiotics to take upon the onset of symptoms, while on their trip.  When attempting self-treatment, the traveler needs to first ensure they are adequately rehydrating.  Rehydration can be achieved with copious amounts of pure water and electrolyte replacement drinks.  Lessening diarrheal symptoms can be accomplished by taking medications designed to decrease the frequency of the stools.  Common choices for symptomatic relief of TD include:

Bismuth-subsalicylate(Pepto-Bismol)
2 tabs or 30mL solution every 30 minutes for 8 total doses

Diphenoxylate-Atropine(Lomotil)
2 tabs for first dose then 1 tab after each loose stool, not to exceed 8 tabs in 24 hours.
Do not use if blood is present in stool.

Loperamide(Imodium)
2 capsules for first dose then 1 capsule after each loose stool, not to exceed 8 capsules in 24 hours.  Do not use of there is blood present in stool.

Caution should be used when taking medications to prevent diarrhea symptoms.  Diarrhea is the body’s way or excreting harmful pathogens and trapping them inside the intestines can cause more harm.  The presence of blood in the stool should prompt one to seek medical treatment and avoid the use of medications designed to prevent diarrhea symptoms. 

Antibiotics for self-treatment of traveler’s diarrhea:  Choice of empiric antibiotic treatment is base on several factors including location of the trip and resistance of local pathogens, age of the traveler and prior medical conditions.  Antibiotic choices should be discussed with a travel health professional prior to the trip.

Trimethoprim160mg/Sulfamethoxazole 800mg(Bactrim, Septra)
One double strength tablet every 12 hours for 3 days
Not to be used by those with sulfa allergy, may be ineffective in some parts of the world due to bacterial drug resistance

Ciprofloxacin500mg (Cipro)
One tablet every 12 hours for 3 days
Not for use by pregnant travelers, children under age 18 years and those with allergies to quinolone antibiotics.  Some drug-drug interactions are possible, especially with caffeine and antibiotic resistance is increasing worldwide

Azithromycin(Zithromax)
One gram as a single dose or 500mg daily for 3 days
The drug of choice for quinolone resistant Campylobacter species

Rifaximin(Xifaxin)
200mg tablet every 8 hours for 3 days
Use with children over the age of 12 years and adults only

 Tetracycline
2.5 grams as a single dose or 500mg every 6 hours for 3-5 days
Not for use by pregnant travelers, children under age 8 years.  May cause vaginal yeast infections and increased sun sensitivity.

Doxycycline
100mg tablet every 8 hours for 3-5 days
Not for use by pregnant travelers, children under age 8 years.  May cause vaginal yeast infections and increased sun sensitivity.  Drug resistance increasing worldwide