Traveler's diarrhea

Physiological and psychological illness symptoms at high altitude and their relationship with acute mountain sickness: a prospective cohort study

BACKGROUND

The aim of this prospective observational cohort study was to investigate relationships between acute mountain sickness (AMS) and physical and mental health during a high altitude expedition.

METHODS

Forty-four participants (mean age, 34 ± 13 y; body mass index, 23.6 ± 3.5 kg·m(2) ; 57% male) completed the Dhaulagiri base camp trek in Nepal, a 19-day expedition attaining 5,372 m. Participants self-reported the following daily physical and mental health: AMS (defined by Lake Louise diagnosis and individual and total symptom scores), upper respiratory symptoms, diarrhea, and anxiety, plus physiological and behavioral factors.

RESULTS

The rate of Lake Louise-defined AMS per 100 person days was 9.2 (95% CI: 7.2-11.7). All investigated illnesses except diarrhea increased with altitude (all p < 0.001 by analysis of variance). Total AMS symptom score was associated with a lower arterial oxygen saturation, higher resting heart rate, more upper respiratory and diarrhea symptoms, greater anxiety, and lower fluid intake (all p < 0.02 by longitudinal multiple regression analyses). However, only upper respiratory symptoms, heart rate, arterial oxygen saturation, and fluid intake predicted future AMS symptoms [eg, an increase in upper respiratory symptoms by 5 units predicted an increase in the following day's AMS total symptom score by 0.72 units (0.54-0.89)].

CONCLUSIONS

Upper respiratory symptoms and anxiety increasingly contributed to symptom burden as altitude was gained. Data were consistent with increased heart rate, decreased arterial oxygen saturation, reduced fluid intake, and upper respiratory symptoms being causally associated with AMS. Upper respiratory symptoms and fluid intake are the simplest targets for intervention to reduce AMS during high altitude exposure.

Expedition medicine--the risk of illness and injury

OBJECTIVE

Expeditions organized by commercial companies are becoming increasingly popular. Charity expeditions take inexperienced participants on trips all over the world, with participants being sponsored to raise funds for charitable causes. The incidence of illness or injury while participating in charity expeditions is unknown. The objective of this study is to report the incidence and severity of illness and injuries occurring on worldwide charity expeditions.

METHODS

Retrospective, observational study reviewing expedition medical reports from 232 expeditions organized by a single commercial expedition company for a 5-year period (January 1, 2004 through December 31, 2008).

RESULTS

Complete expedition medical reports were available for 210 (91%) trips, involving 4077 participants over 1524 expedition days. Expeditions reported a total of 1564 incidents over 42482 participant-days in the field, including days spent traveling to the expedition site. In 1465 (94%) cases "minor" injury or illness was recorded, 79 (5%) "moderate," and 20 (1%) "major" in severity. No deaths were reported. Gastrointestinal upset was the commonest reported minor condition and severe acute mountain sickness the commonest major condition. Overall, the incidence per 1000 participant-days of minor illness or injury was 34.48, moderate illness or injury 1.86, and major illness or injury 0.47.

CONCLUSION

The risk of sustaining major injury or illness on an overseas charity expedition is low. The consequences of becoming injured or unwell in a remote environment can be serious, and appropriate medical care is required.

Infections at high altitude

Every year, thousands of outdoor trekkers worldwide visit high-altitude (>2500 m) destinations. Although high-altitude areas per se do not harbor any specific agents, it is important to know the pathogens encountered in the mountains to be better able to help the ill sojourner at high altitude. These are the same pathogens prevalent in the surrounding lowlands, but various factors such as immunomodulation, hypoxia, physiological adaptation, and harsh environmental stressors at high altitude may enhance susceptibility to these pathogens. Against this background, various gastrointestinal, respiratory, dermatological, neurological, and other infections encountered at high altitude are discussed. Because there are few published data on infections at high altitude, this review is largely anecdotal and based on personal experience.