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Outdoor First Aid

Backcountry Diarrhea: Treating The Runs

When diarrhea strikes in the backcountry and there's no porcelain for 20 miles, the proper response can save your trip.

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Darkness fell and an angry wind gnawed at my tent like a mad dog. I was camped high in Wyoming’s Wind River Range, so the lashing air was to be expected. But what caught me by surprise was the gastrointestinal storm erupting behind my belly button.

In an attempt to limit exposure of my bare bottom to the ice-toothed wind, I had

predug half a dozen catholes within dashing distance of the tent. Over and over through the long night, I repeated the same scenario: out of the bag, rush, squat, dash back.

Technically defined by Taber’s Cyclopedic Medical Dictionary as “frequent passage of unformed watery bowel movements,” diarrhea has laid low much of humanity-kings and common men, women and children-for at least as long as historians have recorded such trivia. It killed nearly as many soldiers in the Civil War as guns and swords did. In developing countries today, acute diarrhea strikes more than 1 billion people a year, leaving more than 5 million dead in its wake.

Thanks to innovations in municipal water treatment, septic systems, and food storage, chronic diarrheal illnesses are seldom a danger in North America. Nevertheless, when backpackers venture outside the world of plumbing, diarrhea is a constant concern. According to findings in the Annals of Emergency Medicine (July 1992), “Viral syndromes and diarrhea account for 60 percent of the illnesses and 45 percent of the illness evacuations [from wilderness programs].”

There are two basic kinds of diarrhea: invasive and noninvasive. A formidable public health problem in many developing countries, invasive diarrhea-also called dysen-

tery-attacks the lower intestinal wall, causing inflammation, abscesses, and ulcers that can lead to mucus and blood in the stools as well as high fever, abdominal cramps, and loss of body fluid from the victim’s nether region. Serious debilitation, even death, can occur from the resulting dehydration and from the spread of the bacteria to other parts of the body.

Noninvasive diarrhea grows from colonies of microscopic evildoers who set up housekeeping on, but don’t invade your intestinal walls. The toxins that are released cause cramps, nausea, vomiting, and massive gushes of fluid from the lower intestinal tract. Noninvasive diarrhea carries a high risk of dehydration, which can become life-threatening if the unfortunate one doesn’t adequately replenish fluids.

I’ll never know what wrought my affliction in the Winds, since diarrhea can be caused by many things, including the flu, spicy foods, and plain old stress. Traveler’s diarrhea (a.k.a. Montezuma’s revenge if you’re visiting Mexico and trekker’s trots if you’re hiking the Appalachian Trail) can erupt after you ingest water or food contaminated by fecal critters of the protozoan, bacterial, or viral variety. This ruthless brand of diarrhea can last as briefly as six hours or longer than three weeks.

In North America’s wildernesses, most diarrheal illnesses have traditionally been the result of waterborne germs deposited by wildlife. Humans, however, are increasingly responsible for making other humans sick in the backcountry with the germs they transport either in their bodies or in their food. The protozoan Giardia lamblia heads the list of waterborne agents that cause the runs, and it invades the guts of wilderness travelers often enough to be dubbed “backpacker’s diarrhea.” But typically only long-distance trekkers become afflicted in the field; it takes one to three weeks (an average of nine days) after swallowing the little bugs before symptoms show up. Among the most unpleasant of non-invasive diarrheas, giardiasis results in loose and foul-smelling stool, cramps, rotten-egg burps, and a loss of energy, appetite, and weight. Treatment usually involves antibiotics.

Cryptosporidium, another protozoan, infects a large number of animals that then leave reminders of their passing in wilderness water. Cramps, nausea, gas, and diarrhea typically cause two-legged distress for about a week. For people suffering from immune deficiency, this kind of diarrhea has extended into years and caused death.

Escherichia coli, a common bacterium that generally inhabits the human gut uneventfully, has a few rogue types that can cause invasive or noninvasive diarrhea. Noninvasive E. coli, believed to be responsible for most cases of traveler’s diarrhea, is typically swallowed in water. It produces headache, nausea, and stinky, watery stools in as little as a few hours after ingestion. Fortunately, the bout ends in one to three days. Invasive strains of E. coli, often ingested via water or food, can cause dysentery.

Campylobacter, another bacterium, lives in the intestines of many wild and domestic animals and ends up in plenty of wilderness lakes and streams. It can also thrive in spoiled food, and it gets credit for infecting 1 percent of the U.S. population every year. After an incubation period of four to seven days, infection brings on general discomfort, fever, cramps, and bloody diarrhea that lasts two to seven days, most often sending the sufferer in search of a doctor.

Salmonella, a variety of bacteria with more than 2,000 types (including S. typhosa, the source of typhoid fever), afflicts an estimated 2.5 million people a year in the United States. Almost all cases arise from contaminated food (especially dairy products, poultry, meat, and eggs) and result in headache, fever, nausea, cramps, and, of course, the runs. Symptoms appear 12 to 24 hours after ingestion of the germs, and they usually go away within a few days.

Shigella, a bacterium responsible for most cases of dysentery, inhabits the waters around the world and is contracted by drinking or even swimming. One to seven days later the illness manifests itself, but most victims in North America recover after a mild case of cramps and watery stools.

Norwalk virus causes more food-related, noninvasive diarrhea than any other viral source. It spreads easily from one person to another, and though it may last a week, the vomiting and diarrhea that follows are mild and rarely require a physician’s care.


Whatever the causative agent, all diarrheal illnesses have one thing in common, and that’s the departure of fluid from the hindmost orifice, sometimes up to 25 liters in 24 hours in severe cases. And it’s not just water your body loses. An impressive amount of electrolytes (potassium and sodium) can be lost as well.

That’s why the single most important step in treating a diarrheal illness in the field is to replace lost water. Your best choices are clear liquids, including water, broth, herbal tea, and clearish fruit juice. If the illness continues and dehydration threatens, you’ll grow weaker, experience bouts of lightheadedness and dizziness, and require additional electrolytes. It’s a smart move to pack Oral Rehydration Salts in your first-aid kit, just in case. A good homemade tonic calls for 1 liter of water, 1 teaspoon of salt, and 8 teaspoons of sugar. Mix well. If you have baking soda, throw in a pinch, but you can get by without it. About one-third of the solution should be taken every hour along with all the plain water you can get down. Look for clear urine, the most reliable field sign of a well-hydrated person.

Pepto-Bismol not only relieves some of the discomfort, according to controlled studies, but also provides reasonable protection against traveler’s diarrhea. Imodium, a stronger over-the-counter drug, reduces the cramps and frequency and volume of stools. The prescription drug Lomotil ranks high among trekkers attempting to control the trots. A word of caution: Antidiarrheal drugs should not be used if you think you have dysentery. Severe diarrhea, bloody stools, high fever, and tenacious vomiting are indications that there’s something inside you that your body eagerly wants to get out. If you suspect that you have dysentery, let the diarrhea flow and find a physician.

When treating diarrhea in the field, stick with liquids until the problem subsides, then eat bland foods such as bread, crackers, cereal, rice, potatoes, lentils, pasta, or bananas. Avoid alcohol, caffeine, spices, fruits, hard cheeses, and other fat-laden products.

Perhaps the only good news about backcountry diarrhea is that it’s almost entirely preventable. Begin by disinfecting all wilderness drinking water through boiling, filtration, or halogenation. Boiling is the safest way, and water need only reach the boiling point to be rendered free of diarrhea-causing critters. Filtration is most effective when the device has been proven to remove protozoans and bacteria, as well as viruses. Halogens (iodine and chlorine) are the least effective because of the variable results based on such things as the concentration of the halogen, contact time with the germs, the clarity of the water, the temperature of the water, and the questionable efficacy of iodine and chlorine against Cryptosporidium.

Other keys to prevention involve proper food handling and camp hygiene. Be sure to carry foods that last a long time before spoiling. Also, eat everything in your pot. The bacteria that grow in leftovers will be killed by reheating the food, but the diarrhea-causing toxins produced by the bacteria are virtually unaffected by heat. Always wash your hands with soap and water after each bowel movement and before preparing food. Religiously wash and dry all community cook gear after use. Keep anyone who even thinks he has an illness out of the kitchen area. Don’t share personal items such as bandannas, cups, water bottles, and eating utensils. Properly dispose of human waste at least 100 yards from the nearest water source.

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