Gastrointestinal illness is a common risk for wilderness travelers, even among those who consistently disinfect their water, yet the importance of hygiene has not been characterized.
In a prospective surveillance study, 334 Appalachian Trail backpackers who hiked for at least 7 days in 1997 were interviewed. Upon completion of their hike, a written questionnaire was sent, addressing illnesses, water disinfection methods, and hygiene. Hygiene inquiries focused on the frequency of behaviors concerning handwashing and cleaning cookware.
Two hundred and eighty backpackers compiled 38, 940 wilderness exposure days, with 56% (n= 156) experiencing diarrhea. Diarrhea correlated with the frequency of drinking untreated surface water (relative risk (RR) 2.4, 95% confidence interval (CI) 1.0–4.7%, p =.03). Of those who consistently treated water, 45% suffered from diarrhea, whereas 69% of those who inconsistently treated water experienced diarrhea (RR 0.65, 95% CI 0.53–0.81%, p =.001). Hikers practicing “good hygiene”, defined as handwashing postdefecation and cleaning cookware routinely, were less likely to ever experience diarrhea (RR 0.47, 95% CI 0.22–0.99, p =.04). Routine handwashing with soap and water after both urination and defecation reduced the risk of diarrhea (RR 0.11, 95% CI 0.04–0.31%, p <.001). In a case-control analysis of those experiencing diarrhea, decreased diarrhea was associated with routine consumption of multivitamins (RR 0.50, 95% CI 0.37–0.66%, p <.001), routine cleaning of utensils with warm, soapy water (RR 0.38, 95% CI 0.20–0.74%, p <.01), and postdefecation handwashing with soap and water (RR 0.61, 95% CI 0.39–0.93%, p =.006).
Lack of hygiene, specifically handwashing and cleaning of cookware, should be recognized as a significant contributor to wilderness gastrointestinal illness. Hikers should routinely disinfect water and avoid untreated surface water.