Wilderness diarrhea
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2008-07-17T04:11:19Z
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Definition of Wilderness diarrhea in question. Citation needed.
'''Wilderness diarrhea''' (WD), also called '''wilderness-acquired diarrhea''' or '''backcountry diarrhea''', is a variety of [[Traveler's diarrhea|traveler’s diarrhea]] (TD) in which backpackers, hikers, campers and other outdoor recreationalists are infected during temporary visits to relatively remote natural areas.{{Fact|date=July 16, 2008}} Risk factors for WD include drinking untreated surface water and failure to maintain personal hygiene practices and clean cookware. Most cases of WD are self-limited and the causative agent is most often never known.
==Names and definitions==
As a variety of TD, WD falls under the more general classification of [[infectious diarrhea]], itself classified (on a physiological basis) as a type of [[Diarrhea#Types of diarrhea|secretory diarrhea]]. These are all considered forms of [[gastroenteritis]].
Conditions in the wilderness can often mimic those in the developing world, with contaminated water sources and poor sanitation and hygiene, but there are of course important differences. The concept of WD has emerged in the context of relatively affluent North American recreationalists visiting areas that have been set aside as protected areas such as [[nature reserve]]s or [[wilderness areas]] (“wildernesses”). The concept may easily be extended to similar recreationalists in other developed countries (such as, for example, those in western Europe or Australia). It is less applicable, however, to Western [[trekking|trekker]]s and other long-term visitors to remote areas of developing countries (such as, for example, [[Nepal]] or the highlands of [[East Africa]]), because of the very different [[epidemiologic]] factors (including distinct [[pathogens]]) prevailing there.
The term “backpacker’s diarrhea” might be an appropriate synonym for WD, but that term has traditionally been reserved for a specific cause of much WD — namely [[giardiasis]] — and the medical literature is fairly consistent in that usage.
==Degree of risk==
Rigorous scientific research on the causes and degrees of risk for WD has not been extensive. However, diarrhea has been found to be the most common illness afflicting long-distance hikers in the United States<ref>Boulware DR, et al (2003), “Medical Risks of Wilderness Hiking”, ''Am J Med'', 114(4):288-93.</ref>. In one recent study of [[Appalachian Trail]] (AT) hikers<ref> Boulware (2003), ''Op. cit.''</ref>, the risk of diarrhea was greater among those who frequently drank untreated water from streams or ponds, whereas practicing "good hygiene" (defined as routine cleaning of cooking utensils and cleaning hands after bowel movements) was associated with a decreased risk. In a subsequent study of AT hikers<ref>Boulware DR, (2004), “Influence of Hygiene on Gastrointestinal Illness Among Wilderness Backpackers”, ''J Travel Med'', Jan-Feb;11(1):27-33.</ref>, the role of hygiene was confirmed and diarrhea again correlated with the frequency of drinking untreated surface water. (Of those who consistently treated water, 45% suffered from diarrhea, whereas 69% of those who inconsistently treated water experienced it.)
It has been shown that most diarrhea-causing organisms, including ''[[Shigella]]'' species and ''[[Salmonella typhi]]'', hepatitis A virus, and ''[[Cryptosporidium]]'' species, can survive for weeks to months when frozen in water<ref>Dickens DL, DuPont HL, Johnson PC (1985), "Survival of Bacterial Enteropathogens in the Ice of Popular Drinks", ''[[JAMA]]''; 253:3141–3.</ref>.
Virologists are in agreement that all surface water supplies in the United States and Canada contain naturally occurring human [[enterovirus]]es, which are potentially disease-causing<ref>Backer, Howard (2000), "In Search of the Perfect Water Treatment Method", ''[[Wilderness and Environmental Medicine]]'', 11:1-4.</ref><ref>Gerba, C and J Rose (1990), "Viruses in Source and Drinking Water", In: McFeters G, ed., ''Drinking Water Microbiology'', [[New York, New York]]: [[Springer-Verlang]], pp 380-399</ref><ref>White, G (1992), ''Handbook of Chlorination'', 3rd edition, New York, New York: [[Van Nostrand Reinhold]].</ref>.
==Causes==
In discussing the etiology (causes) of WD, it must be realized that so little research has been specifically directed at diarrhea in a recreational “wilderness” context that it is difficult to distinguish the range of agents causing WD from those causing other types of TD, as well as from those causing water-borne diarrhea where the source of infection is community plumbing or recreational public water such as swimming pools or amusement “water parks”. Nevertheless, one recent authority <ref>Backer, Howard D. (2007), “Field Water Disinfection”, In: Auerbach, Paul S. (editor), ''Wilderness Medicine'', 5th edition, [[Philadelphia, Pennsylvania]]: [[Mosby Elsevier]], pg 1369.</ref> has presented a frequency distribution of “Enteric Pathogens in U.S. Wildernesses or Recreational Water” as follows. By far the most common causes of diarrhea in this context are the parasites ''[[Giardia lamblia|Giardia]]'' and ''[[Cryptosporidium]]''. Those that are occasionally reported, and have a fair degree of certainly as being the water-borne agent in question, include ''[[Campylobacter]]'', [[hepatitis A virus]], [[hepatitis E virus]], enterotoxogenic ''[[E. coli]]'', ''E. coli'' 0157:H7, ''[[Shigella]]'', and various [[enterovirus|enteric viruses]]. Agents which may in very unusual circumstances cause diarrhea under these circumstances include ''[[Yersinia enterocolitica]]'', ''[[Aeromonas hydrophila]]'', and ''[[Cyanobacterium]]''.
==Symptoms==
The onset of WD usually occurs within the first week of return from the field, but may also occur at any time while hiking, particularly if the trip is several days in duration. The [[incubation period]] for giardiasis averages about 14 days and that of cryptosporidiosis about 7 days. Bacterial and viral agents generally have shorter incubation periods, although viral hepatitis may take weeks to manifest itself. Most WD cases begin abruptly. The illness usually results in increased frequency, volume, and weight of stool. Altered stool consistency also is common. 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 low or non-existent. Diarrhea is much more serious if there is blood or [[mucus]] in the diarrhea, abdominal pain, or high fever. [[Dehydration]] is a possibility. Serious, life-threatening illness is rare in the context of WD.
==Treatment==
WD usually is a self-limited [[disease|disorder]] and generally resolves without specific treatment; however, [[oral rehydration therapy]] is often beneficial to replace lost fluids and [[electrolytes]]. Clear liquids are routinely recommended for adults. Water that is purified is best, along with oral rehydration salts to replenish lost [[electrolyte]]s. [[Carbonated water]] (soda), which has been left out so that the [[carbonation]] fizz is gone, is quite useful.{{Fact|date=February 2008}}
Hikers who develop three or more loose stools in a 24-hour period — especially if associated with [[nausea]], [[vomiting]], [[abdominal]] [[cramps]], [[fever]], or [[blood in stool]]s — should be treated by a doctor and may benefit from [[antimicrobial]] therapy. [[Antibiotic]]s usually are given for 3–5 days, but single dose [[azithromycin]] or [[levofloxacin]] have been used.<ref>{{cite journal|title=Azithromycin and Loperamide are Comparable to Levofloxacin and Loperamide for the Treatment of Traveler's Diarrhea in United States Military Personnel in Turkey|author=Sanders JW, Frenck RW, Putnam SD, ''et al.''|journal=Clin Infect Dis|year=2007|volume=45|pages=294–301|url=http://www.journals.uchicago.edu/CID/journal/issues/v45n3/50169/brief/50169.abstract.html|doi=10.1086/519264}}</ref> If diarrhea persists despite therapy, travelers should be evaluated and treated for possible parasitic infection.
Specific anti-infectives are required to treat bacterial [[dysentery]], for amoebic dysentery, for giardia and for [[helminths|worms]]. There is no antibiotic effective against ''[[Cryptosporidium]]'', which can devastate people with [[AIDS]].
==Prevention==
Judgments of water safety cannot reliably be made on the basis of the look, smell, and taste of surface water. Conventional guidelines caution that even in the pristine wilderness, surface waters of lakes and streams may be contaminated. Hikers therefore should purify water routinely, avoiding the ingestion of untreated surface water from streams or ponds. It has recently been recognized that the risk of WD can also be reduced by maintaining personal hygiene practices<ref>Boulware (2004), ''Op. cit.''</ref>. Specifically, handwashing and cleaning of cookware with both soap and water have been shown to be protective behaviors diminishing diarrhea.
A variety of water disinfection methods that are lightweight, durable and reliable, for the removal of common bacterial and parasitic pathogens, are available commercially (see [[Portable water purification]]). The best water-treatment technique to be used by an individual or group in the wilderness depends upon the number of people involved, space and weight considerations, the quality of the available water, personal taste and preferences, and fuel availability. It has been shown that the most significant factor in preventing diarrheal illness in the wilderness is the regularity of water disinfection. Inconsistent use of iodine or chlorine may be due to disagreeable taste, impatience with extended treatment time or excessive treatment complexity due to water temperature and turbidity. For this reason, it has been suggested that for long-distance backpacking, water filtration is a preferred method of disinfection because it is more likely to be persistently and correctly used.
Because methods based on [[halogens]] do not kill ''Cryptosporidium'', and because filtration misses some of the viruses, the best protection for all situations may require a two-step process of either filtration or [[coagulation-flocculation]], followed by halogenation. Heat is effective as a one-step process in all situations, but it will not generally improve the palatability of water. Iodine resins, if combined with microfiltration to remove resistant cysts, are also a viable single-step process, but may not be effective under all conditions. The new techniques that use chlorine dioxide, ozone, and UV radiation may prove to be effective one-step techniques, but still require validation in studies.<ref> Backer, Howard (2002), "Water Disinfection for International and Wilderness Travelers", ''Clinical Infectious Diseases''; 34:355–64.</ref>.
==Potability of wilderness surface water==
The potability of surface water in any particular hiking/camping locality is always uncertain, and accurate categorical statements regarding the safety of untreated drinking water in “backcountry” or “wilderness” areas are impossible to make as conditions naturally change according to geography and time. Any investigational findings are necessarily temporary since the quality of water depends on recent activity in the watershed, such as rainfall, human and animal activity, and other factors. However, it is generally accepted that, even in the pristine wilderness, surface waters (i.e. lakes and streams) always have the potential to be contaminated<ref>Gentile DA, et al. (1992), “Wilderness Injuries and Illnesses”, ''Ann Emerg Med'', 21:853–861.</ref> <ref>Backer (2002), ''Op. cit.''</ref> There is, however, little rigorous public health or scientific literature to confirm this generally accepted view.
Robert Rockwell, an engineer by training, has made an ongoing review of the scientific literature on this topic since the late 1980s. Building on previous skeptics, Rockwell quotes James Wilkerson's ''Medicine for Mountaineering and Other Wilderness Activities'' ([[Seattle, Washington]]: [[The Mountaineers Books]], 4th edition, 1992):
:"In recent years, frantic alarms about the perils of [[giardiasis]] have aroused exaggerated concern about this infestation. Government agencies, particularly the [[National Park Service|U.S. Park Service]] and the [[National Forest Service]], have filtered hundreds of gallons of water from wilderness streams, found one or two organisms (far less than enough to be infective), and erected garish signs proclaiming the water hazardous."
Rockwell's survey of literature pertains specifically to the [[Sierra Nevada]] in [[California]], where he concludes that one can find untreated surface water that is safe to drink by avoiding potentially unsafe water using a list of rules that he calls "drink smart".<ref name=Rockwell2003June>[http://lomaprieta.sierraclub.org/pcs/articles/giardia.asp ''Giardia Lamblia and Giardiasis''] by Robert L. Rockwell, June 4, 2003, Loma Prieta Chapter of the Sierra Club website. Accessed Nov 6, 2006.</ref> As an example, one of his "drink smart" rules advises people to take water from the inlet or outlet of a lake. He notes that inlet water has a tendency to flow somewhat directly to the outlet, undergoing little mixing with the rest of the lake water. He asserts that the survey has similar implications for other backcountry regions throughout the U.S. and Canada<ref>Although backcountry water is not routinely tested as a [[public water supply]] is, tests that have been done in the [[Sierra Nevada (U.S.)|Sierra Nevada]] of [[California]] found low levels of [[coliform bacteria]] such as [[Escherichia coli]]. Many samples showed no coliform bacteria at all; others showed more, especially in areas with [[cattle]] gazing or heavy human activity. Derlet, Robert W., James R. Carlson and Mikla N. Noponen (2004), [http://www.wemjournal.org/wmsonline/?request=get-abstract&issn=1080-6032&volume=015&issue=04&page=0245 Coliform and Pathologic Bacteria in Sierra Nevada National Forest Wilderness Area Lakes and Streams], ''Wilderness and Environmental Medicine'', V. 15:4, pp 245–249</ref>.
Rockwell believes that "Giardia and other intestinal bugs are for the most part spread by direct fecal-oral or food-borne transmission, not by contaminated drinking water. Since personal hygiene often takes a backseat when camping, the possibility of contracting giardiasis from someone in your own party someone who is asymptomatic, probably is real. Recalling that up to 7 percent of Americans, or up to 1 in 14, are infected, it is not surprising that wilderness visitors can indeed come home with a case of giardiasis, contracted not from the water...but from one of their friends."<ref name=Rockwell2003June/>
Rockwell and other doubters received some support from a large-scale review in 2000 by Thomas Welch, MD, of the [[Tulane School of Public Health]], which attempted to include all the relevant literature<ref>Welch TP (2000), [http://www.ncbi.nlm.nih.gov/pubmed/10737847?dopt=Citation "Risk of Giardiasis from Consumption of Wilderness Water in North America: A Systematic Review of Epidemiologic Data"], ''Int J Infect Dis''; 4(2):100-3.</ref>. Welch came to the startling conclusion (for a public health physician) that water filtration and disinfection is generally not necessary in the U.S. backcountry. Later, in a paper for the [[Wilderness Medical Society]] <ref> Welch, Thomas R. (2004), [http://www.wemjournal.org/pdfserv/i1080-6032-015-04-0235.pdf “Evidence-Based Medicine in the Wilderness: The Safety of Backcountry Water”], ''Wilderness and Environmental Medicine''; 15, 235 237</ref>
, Welch wrote:
<blockquote>
It must be impressed upon backpackers (just as it is impressed upon health care, food industry, and daycare workers) that stopping hand-to-mouth spread is the key to preventing gastrointestinal infection. Diluting this message with unfounded concerns about wilderness water quality or the relative merits of various water-treatment methods serves no useful purpose.
</blockquote>
Welch further claims:
<blockquote>The most comprehensive recent look at the problem was not in the medical literature, but rather in the lay magazine ''[[Backpacker (magazine)|Backpacker]]''<ref>Jaret, P. (2003), “What's in the Water?”, ''Backpacker''; 31:45–65.</ref>. The editors of this widely read publication sampled several backcountry waters for 2 pathogens (''Giardia'' and ''Cryptosporidium'') commonly worried about in the backcountry. Although a few areas yielded positive isolates, in each case the concentration of pathogens was below that which would be expected to result in disease with casual (as opposed to ongoing) use. The highest concentration of ''G. lamblia'' found, for example, was 1.5 cysts per liter. Even if one happened upon this spot, it would take nearly 7 L of water consumption to achieve the minimum infective dose of this organism.
</blockquote>
The skepticism of Rockwell and Welch, however, seems to have had little impact on the guidelines and advice offered in major medical textbooks which continue to consider drinking untreated surface water in the wilderness unsafe, to advise water disinfection and to describe the available commercial water treatment devices in detail. An example is the newest (2007) edition of Auerbach’s ''Wilderness Medicine'':<blockquote>The majority of pathogens that cause traveler’s diarrhea or wilderness-acquired diarrhea can be either food-borne or water borne; however, waterborne pathogens from drinking untreated surface water or from an inadvertent ingestion during water recreational activity probably account for most infectious diarrhea acquired in the U.S. wilderness. Avoidance of all these pathogens requires proper sanitation and water disinfection.<ref>Adachi, Javier A., Howard D. Backer, and Herbert L. Dupont (2007), “Infectious Diarrhea from Wilderness and Foreign Travel”, In: Auerbach, Paul S. (editor), ''Wilderness Medicine'', 5th edition, [[Philadelphia, Pennsylvania]]: [[Mosby Elsevier]], pg 1418.</ref> </blockquote>
==References==
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[[Category:Hiking]]
[[Category:Camping]]
[[Category:Drinking water]]
[[Category:Water-borne diseases]]
[[Category:Gastroenterology]]
[[Category:Foodborne illnesses]]
[[Category:Infectious diseases]]
[[Category:Symptoms]]
[[Category:Digestive disease symptoms]]
[[Category:Conditions diagnosed by stool test]]
[[Category:Wilderness areas]]
[[Category:Wilderness|*]]