biology

Wilderness-acquired diarrhea

Wilderness-acquired diarrhea is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Wilderness-acquired diarrhea rather than just read about it. In short: Wilderness-acquired diarrhea is a variety of traveler's diarrhea in which backpackers and other outdoor enthusiasts are affected. Potential sources are contaminated food or water, or "hand-to-mouth", directly from another person who is infected.

Key takeaways

Wilderness-acquired diarrhea belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Wilderness-acquired diarrhea to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Wilderness-acquired diarrhea from memory before moving on to harder problems.

Reference excerpt

Wilderness-acquired diarrhea is a variety of traveler's diarrhea in which backpackers and other outdoor enthusiasts are affected. Potential sources are contaminated food or water, or "hand-to-mouth", directly from another person who is infected. Cases generally resolve spontaneously, with or without treatment, and the cause is typically unknown. The National Outdoor Leadership School has recorded about one incident per 5,000 person-field days by following strict protocols on hygiene and water treatment. More limited, separate studies have presented highly varied estimated rates of affliction that range from 3 percent to 74 percent of wilderness visitors. One survey found that long-distance Appalachian Trail hikers reported diarrhea as their most common illness. Based on reviews of epidemiologic data and literature, some researchers believe that the risks have been over-stated and are poorly understood by the public.

Symptoms and signs The average incubation periods for giardiasis and cryptosporidiosis are each 7 days. Certain other bacterial and viral agents have shorter incubation periods, although hepatitis may take weeks to manifest itself. The onset usually occurs within the first week of return from the field, but may also occur at any time while hiking. Most cases begin abruptly and usually result in increased frequency, volume, and weight of stool. Typically, a hiker experiences at least four to five loose or watery bowel movements each day. Other commonly associated symptoms are nausea, vomiting, abdominal cramping, bloating, low fever, urgency, and malaise, and usually the appetite is affected. The condition is much more serious if there is blood or mucus in stools, abdominal pain, or high fever. Dehydration is a possibility. Life-threatening illness resulting from WAD is extremely rare but can occur in people with weakened immune systems. Some people may be carriers and not exhibit symptoms.

Causes Infectious diarrhea acquired in the wilderness is caused by various bacteria, viruses, and parasites (protozoa). The most commonly reported are the protozoa Giardia and Cryptosporidium. Other infectious agents may play a larger role than generally believed and include Campylobacter, hepatitis A virus, hepatitis E virus, enterotoxogenic E. coli, E. coli O157:H7, Shigella, and various other viruses. More rarely, Yersinia enterocolitica, Aeromonas hydrophila, and Cyanobacterium may also cause disease. Giardia lamblia cysts usually do not tolerate freezing although some cysts can survive a single freeze–thaw cycle. Cysts can remain viable for nearly three months in river water when the temperature is 10 °C and about one month at 15–20 °C in lake water. Cryptosporidium may survive in cold waters (4 °C) for up to 18 months, and can even withstand freezing, although its viability is thereby greatly reduced. Many other varieties of diarrhea-causing organisms, including Shigella and Salmonella typhi, and hepatitis A virus, can survive freezing for weeks to months. Virologists believe all surface water in the United States and Canada has the potential to contain human viruses, which cause a wide range of illnesses including diarrhea, polio and meningitis. Modes of acquiring infection from these causes are limited to fecal-oral transmission, and contaminated water and food. The major factor governing pathogen content of surface water is human and animal activity in the watershed.

Diagnosis It may be difficult to associate a particular case of diarrhea with a recent wilderness trip of a few days because incubation of the disease may outlast the trip. Studies of trips that are much longer than the average incubation period, e.g. a week for Cryptosporidium and Giardia, are less susceptible to these errors since there is enough time for the diarrhea to occur during the trip. Other bacterial and viral agents have shorter incubation periods, although hepatitis may require weeks. A suspected case of wilderness-acquired diarrhea may be assessed within the general context of intestinal complaints. During any given four-week period, as many as 7.2% of Americans may experience some form of infectious or non-infectious diarrhea. There are an estimated 99 million annual cases of intestinal infectious disease in the United States, most commonly from viruses, followed by bacteria and parasites, including Giardia and Cryptosporidium. There are an estimated 1.2 million U.S. cases of symptomatic giardiasis annually. However, only about 40% of cases are symptomatic.

Prevention Since wilderness acquired diarrhea can be caused by insufficient hygiene, contaminated water, and (possibly) increased susceptibility from vitamin deficiency, prevention methods should address these causes.

Hygiene The risk of fecal-oral transmission of pathogens that cause diarrhea can be significantly reduced by good hygiene, including washing hands with soap and water after urination and defecation, and washing eating utensils with warm soapy water. Additionally a three-bowl system can be used for washing eating utensils.

Treating water

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Wilderness-acquired diarrhea

Start with the simplest possible case. Write down what Wilderness-acquired diarrhea claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Wilderness-acquired diarrhea before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Wilderness-acquired diarrhea ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Wilderness-acquired diarrhea

In research: Wilderness-acquired diarrhea appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Wilderness-acquired diarrhea in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Wilderness-acquired diarrhea is common in secondary-school and first-year university syllabi. It links to neighbouring topics Camping, Conditions diagnosed by stool test, Diarrhea, so understanding it makes those chapters shorter.
In everyday life: Look for Wilderness-acquired diarrhea outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Wilderness-acquired diarrhea in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Wilderness-acquired diarrhea means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Wilderness-acquired diarrhea out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Wilderness-acquired diarrhea in simple terms?

Why does Wilderness-acquired diarrhea matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Wilderness-acquired diarrhea?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Wilderness-acquired diarrhea.