The risk of acquiring infectious diarrhea in the<unk>  arises from inadvertent ingestion of pathogens. Various studies have sought to estimate diarrhea attack rates among<unk>  travelers, and results have ranged widely. The variation of diarrhea rate between studies may depend on the time of year, the location of the study, the length of time the hikers were in the<unk> , the prevention methods used, and the study methodology. The National Outdoor Leadership School (NOLS), which emphasizes strict hand-washing techniques, water disinfection and washing of common cooking utensils in their programs, reports that gastrointestinal illnesses occurred at a rate of only 0.26 per 1000 program days. In contrast, a survey of long-distance Appalachian Trail hikers found more than half the respondents reported at least one episode of diarrhea that lasted an average of two days. (Infectious diarrhea may last longer than an average of two days; certain forms of non-infectious diarrhea, caused by diet change etc., can be of very brief duration). Analysis of this survey found occurrence of diarrhea was positively associated with the duration of exposure in the<unk> . During any given four-week period, as many as 7.2% of Americans may experience some form of infectious or non-infectious diarrhea. A number of behaviors each individually reduced the incidence of diarrhea: treating water; routinely washing hands with soap and water after defecation and urination; cleaning cooking utensils with soap and warm water; and taking multi-vitamins. A variety of pathogens can cause infectious diarrhea, and most cases among backpackers appear to be caused by bacteria from feces. A study at Grand Teton National Park found 69% of diarrhea affected visitors had no identifiable cause, that 23% had diarrhea due to Campylobacter and 8% of patients with diarrhea had giardiasis. Campylobacter enteritis occurred most frequently in young adults who had hiked in<unk>  areas and drunk untreated surface water in the week prior. Another study tested 35 individuals before and after a trip to the Desolation<unk>  of California. Giardia cysts were found in fecal samples from two people after the trip, but they were asymptomatic. A third person was empirically treated for symptoms of giardiasis. Fecal-oral transmission may be the most common vector for<unk> . There are differing opinions regarding the importance of routine disinfection of water during relatively brief backcountry visits. Backcountry water quality surveys Infection by fecal coliform bacteria, which indicate fecal pollution, are more common than giardiasis. Risks are highest in surface water near trails used by pack animals and cattle pastures. Most samples of backcountry water in the Desolation<unk>  in California have found very low or no Giardia cysts. The infectious dose of giardia, however, is very low, with about 2% chance of infection from a single cyst. Also, very few studies have addressed the issue of transient contamination. According to one researcher, the likely model for the risk of Giardia from<unk>  water is pulse contamination, that is, a brief period of high cyst concentration from fecal contamination.
Wilderness-acquired diarrhea
Antibiotic-associated diarrhea
Travelers' diarrhea
Factitious diarrhea
Porcine epidemic diarrhoea
Riga–Fede disease
Food protein-induced enterocolitis syndrome
Brainerd diarrhea