Environmental Hazards in Nepal: Altitude Illness, Environmental Exposures, Injuries, and Bites in Travelers and Expatriates
A. K. B. and K. C. K. contributed to the study design, data acquisition, analysis, and interpretation and were primarily responsible for writing the manuscript. C. C. and P. P. contributed to the study design, data acquisition, and analysis and revised the manuscript for critical content.
Andrea K. Boggild, MSc, MD, Department of Microbiology, Mount Sinai Hospital, 600 University Avenue, Room 1485, Toronto, ON, Canada M5G 1X5. E-mail: firstname.lastname@example.org
Background Adventure travel necessarily places travelers at risk of environmental hazards. We assessed the burden of “environmental” hazards among a cohort of travelers and expatriates presenting to a large travel clinic in Nepal.
Methods Data on travelers and expatriates seen at the Canadian International Water and Energy Consultants (CIWEC) clinic in Kathmandu were prospectively collected and entered into the GeoSentinel Surveillance Network database. Data on individuals receiving predefined diagnoses related to environmental hazards were extracted and analyzed.
Results Of 10,499 travelers and 4,854 expatriates in the database, 2,160 were diagnosed with 2,533 environment-related illnesses. Injuries were common among both travelers and expatriates [N= 788 (6.1%) and 328 (4.9%), respectively], while altitude illness was seen almost exclusively in travelers [N= 611 (4.7%) vs N= 8 (0.1%)]. Factors independently associated with environmental diagnoses include male gender (p < 0.001), traveling for tourism (p < 0.001), and lack of pre-travel advice (p= 0.043). Three percent of travelers and 2% of expatriates presenting to CIWEC sustained a bite wound or required rabies postexposure prophylaxis. Injured travelers were less likely than others to have obtained pre-travel advice (p= 0.003), while those who sustained bite wounds were more likely to have received pre-travel advice (p < 0.001).
Conclusions Environmental hazards are important causes of morbidity and potential mortality among adventure travelers and expatriates. Current pre-travel interventions are missing certain risk groups entirely and failing to have the desired educational impact in others.
Of the approximate 50 million residents of industrialized nations who travel to the developing world each year, 20% to 70% will report a travel-related illness,1,2 and up to 8% will seek medical attention upon returning home or while abroad.2,3 Of those seeking medical attention during travel, up to 10% will require medical evacuation,3 and 1% in 100,000 will ultimately die of a travel-related illness.3
Adventure travel, which is both the newest and the fastest-growing sector of the tourism industry, generally involves physical exertion in an unusual, exotic, or wilderness setting.4 This form of travel inherently places visitors at risk for various environmental illnesses and injuries,4,5 including high-altitude illness, which describes the mild-to-severe cerebral and pulmonary sequela that can develop in unacclimatized persons shortly after ascent to high altitude. Skiers, mountaineers, and trekkers routinely ascend to altitudes of 3,000 to 8,000 m for leisure and may develop altitude illness when they ascend without adequate acclimatization.6 In addition to those seeking recreation at altitude, approximately 140 million people reside at altitude more than 2,500 m,7 and many more commute to high altitude for work.6,8,9 In any given year, therefore, millions of individuals are at risk of developing high-altitude illness, which is a public health concern with a significant economic burden.10
Exposure to harsh climates during adventure travel may lead to other problems in travelers such as dehydration,11 frostbite,12 and photodermatitides.13 Moreover, adventure travel has the propensity to introduce travelers to unfamiliar and potentially hostile indigenous fauna,11,12 such as dogs or monkeys, which have the potential to transmit rabies,14 among other zoonoses.
The popularity of Nepal as a tourist destination has increased dramatically over the past decade, with over 300,000 non-Indian tourists arriving each year.14 Approximately one third of these travelers visit Nepal for the purpose of trekking.14 Data on environmental illnesses experienced by these travelers are scant. In addition to the tourist population, a large expatriate population resides in Kathmandu, the environmental health of which has also been little reported. Through use of data collected as part of the GeoSentinel Surveillance Network15,16 project, we have investigated the burden of environmental conditions such as altitude illness, injuries, bites, and climate-related disease in travelers and expatriates presenting to a large travel clinic in Nepal over a 7-year period. We herein describe the demographic, clinical, and travel-related features associated with these diagnoses.
Data on travelers and expatriates living in Nepal, who were seen in the Canadian International Water and Energy Consultants (CIWEC) clinic in Kathmandu, were entered into the central database of the GeoSentinel Surveillance Network according to a standardized protocol,15,16 and data from this single network site were extracted for this analysis. Persons attending the CIWEC clinic are mainly travelers and expatriates from the United States, Canada, Western Europe, Japan, Australia, and New Zealand. In the case of acute mountain sickness (AMS), most severely ill patrons of CIWEC arrive within 24 hours of becoming critically ill, usually via helicopter while a smaller proportion of mountain rescues will access the clinic after 1 to 3 days of becoming critically ill, if weather conditions prevent immediate evacuation. While there are several other clinics and hospitals in Kathmandu and the surrounding areas that service “Western” tourists and expatriates, CIWEC attends to the majority of these patients.
As per GeoSentinel protocol, prospectively established variables of interest, including demographic data such as age, gender, and birth country, and recent and previous travel-related data, including destinations and dates, were collected from patients on arrival. Physicians recorded the patient’s status in Nepal (patient classification), their purpose of travel, and chief complaint. Following a diagnostic work-up, which was at the discretion of the attending physician, and based on current laboratory protocols, a final diagnosis was reported. Demographic, clinical, and travel-related data on travelers and expatriates who received specific environmental diagnoses after being evaluated at CIWEC between July 15, 1998, and March 15, 2005, were extracted for this study.
The following definitions were used in the study:
- 1Patient classification—Patients were classified into one of the following two groups: traveler (foreign visitors, students, and travelers/tourists) and expatriates. The category “expatriates” refers to nonnative, foreign-born aliens living in Nepal, the majority of whom hail from Western countries such as the United States, Canada, Western Europe, and Japan. Immigrants/refugees or military personnel were excluded from this analysis.
- 2Reason for most recent travel—The five possible purposes of travel were tourism, business, research/education, missionary/volunteer, or visiting friends and relatives (VFR). Persons traveling to immigrate to Nepal were excluded from the analysis.
- 3Diagnoses—For the purposes of this study, only data on individuals who received as their “probable” or “confirmed” diagnosis a specific “environmental illness” were analyzed. Environmental illness is an umbrella term encompassing categories of disease, including injuries (lacerations, sprains, fractures, etc.), altitude illness [AMS, high-altitude cerebral edema (HACE), high-altitude pulmonary edema (HAPE)], bites (animal or arthropod), and exposure-related diagnoses (dehydration, frostbite, heat exhaustion, etc.), that may result from an individual’s direct interaction with their environment. Patients identified with AMS, HACE, and HAPE met diagnostic criteria as described previously.17 A comprehensive GeoSentinel Network–wide analysis of 320 animal-associated injuries in returned travelers over a 7-year period is provided by Gautret and colleagues.18
Extracted data were managed in a Microsoft Access database and analyzed using standard parametric and nonparametric techniques. Comparisons between categorical variables were made using Yates’ corrected chi-square analysis or calculated odds ratios (OR) with 95% confidence intervals (CI), while continuous variables were analyzed for significant differences using unpaired, two-tailed t-test. In the case of nonnormally distributed samples, ordinally transformed continuous variables were compared using the Mann–Whitney rank sum test. Demographic variables that achieved statistical significance in univariate analysis (p < 0.05) were entered into a forward stepwise logistic regression model to evaluate the independent contribution of these variables to an environmental diagnosis. OR were calculated comparing the odds of a particular gender, purpose of travel, or patient classification in the presence or absence of a particular environmental diagnosis. As CIWEC sees the majority of ill tourists and expatriates in the Kathmandu catchment area, the denominator for OR calculations was assumed to represent all ill tourists or all ill expatriates presenting for care in Kathmandu during travel. All statistical computations were performed using SigmaStat 2.03 software (SPSS Inc., Chicago, IL, USA).
Between July 1998 and March 2005, 15,462 patients were seen at the CIWEC clinic in Kathmandu and were given “probable” or “confirmed” final diagnoses. Of these patients, 46.4% were male, and median age was 31 (range 0–91) years. Collectively, these patients received 19,770 diagnoses, 2,533 of which (12.8%) fell under the umbrella of an environmental diagnosis. Of the 15,462 patients, 10,499 were classified as “travelers” and 4,854 were classified as “expatriates.” Males accounted for 47.7 and 43.4% of travelers and expatriates, respectively. Among travelers, 16.6% received an environmental diagnosis, whereas 8.7% of expatriates were diagnosed with such illnesses. Common diagnoses are summarized in Table 1.
Table 1. Diagnostic categories of environmental hazards among travelers and expatriates in Nepal
|Injuries||788 (6.1)||328 (4.9)|
| Lacerations||201 (1.6)||101 (1.5)|
| Sprains/strains||218 (1.7)||75 (1.1)|
| Fractures||163 (1.3)||43 (0.6)|
| Head injuries||25 (0.2)||18 (0.3)|
| Burns||16 (0.1)||9 (0.1)|
| Other*||165 (1.3)||82 (1.2)|
|Altitude illness||611 (4.7)||8 (0.1)|
| HAPE||268 (2.1)||4 (0.06)|
| HACE||178 (1.4)||2 (0.03)|
| AMS alone||165 (1.3)||2 (0.03)|
|Bites||423 (3.3)||121 (1.8)|
| Animal bite†||174 (1.3)||44 (0.7)|
| Dog||118 (0.9)||34 (0.5)|
| Cat||9 (0.07)||7 (0.1)|
| Monkey||40 (0.31)||1 (0.01)|
| Other||7 (0.05)||2 (0.03)|
| Rabies PEP||139 (1.1)‡||27 (0.4)§|
| Arthropod bite||87 (0.7)||47 (0.7)|
| Monkey scratch||21 (0.2)||3 (0.04)|
| Human bite||1 (0.001)||0|
| Marine sting||1 (0.001)||0|
|Exposure-related illness||231 (1.8)||23 (0.3)|
| Dehydration||125 (1.0)||15 (0.2)|
| Frostbite||96 (0.7)||2 (0.03)|
| Photodermatitis||5 (0.004)||4 (0.06)|
| Heat rash||5 (0.004)||2 (0.03)|
Of all environment-related conditions analyzed, injuries were the most common and were well represented among both travelers and expatriates, accounting for 38 and 68% of all environmental diagnoses identified in the database, respectively (Table 1). Lacerations, sprains, strains, and fractures were the most common injuries sustained (Table 1). Males were disproportionately represented among expatriates who sustained injuries (52% male); however, no such gender bias existed among travelers who sustained injuries (Table 2). Expatriates presenting to CIWEC were more likely than travelers to be diagnosed with a head injury (OR: 1.8, 95% CI: 1.0–3.3).
Table 2. Epidemiologic data for travelers and expatriates in Nepal
|Travelers (N= 10,499)||5,010 (47.7)||5,489 (52.3)||30||0–91|
| All environment-related illness (N= 1,736)||933 (53.7)*,†||803 (46.3)||35||0–83|
| Injuries (N= 724)||348 (48.1)||376 (51.9)||33||0–83|
| Altitude illness (N= 498)||315 (63.3)‡||183 (36.7)||43§||14–77|
| Bites (N= 302)||135 (44.7)||167 (55.3)||28.5‖||0–73|
| Exposure-related conditions (N= 230)||145 (63.0)¶||85 (37.0)||31||2–73|
|Expatriates (N= 4,854)||2,105 (43.4)||2,749 (56.6)||35||0–83|
| All environment-related illness (N= 421)||201 (47.7)||220 (52.3)||33||0–80|
| Injuries (N= 297)||153 (51.5)#||144 (48.5)||34||0–80|
| Altitude illness (N= 6)||3 (50.0)||3 (50.0)||34||18–56|
| Bites (N= 101)||41 (40.6)||60 (59.4)||30||1–70|
| Exposure-related conditions (N= 23)||7 (30.4)||16 (69.6)||34||2–58|
Six (1.2%) expatriates and 498 (4.7%) travelers were diagnosed with high-altitude illness. Some received more than one diagnosis, thus the total number of altitude-related diagnoses among travelers was 611 and 8 among expatriates (Table 1). Males were overrepresented in this category accounting for 63% of altitude sickness among travelers (χ2= 50, p < 0.001, OR: 1.9, 95% CI: 1.6–2.3). This gender disparity was most pronounced with the diagnoses HAPE and HACE for which 68 and 63% of sufferers were male. AMS had a more even gender distribution with only 53% of sufferers being male. Travelers receiving altitude diagnoses were significantly older than other travelers (median age 43 vs 30 y, p < 0.001) (Table 2).
Three percent of all travelers and 2% of expatriates seen and diagnosed at the CIWEC clinic sustained some sort of bite wound in Nepal, and/or required rabies postexposure prophylaxis (PEP) (Table 1). Animal bites, particularly from dogs and primates, were most common (Table 1). Interestingly, monkey bites accounted for 23% of all animal bites in travelers compared with only 2% of animal bites in expatriates (p < 0.001, OR: 12.8, 95% CI: 7.5–96). Rabies PEP was given to 139 travelers and 27 expatriates (Table 1). While no gender bias was observed among recipients of bites, travelers who sustained bite wounds were younger than travelers who presented with other environment-related illnesses (median age 28.5 vs 35 y, p < 0.001) (Table 2).
Exposure-related conditions were the least well represented among all environmental diagnoses, though within this category, dehydration and frostbite occurred most often (Table 1). Among travelers, males were more likely than females to receive an exposure-related diagnosis (χ2= 20.7, p < 0.001, OR: 1.9, 95% CI: 1.4–2.4) (Table 2).
Purpose of travel data for travelers are summarized in Table 3. Of the 10,499 “travelers” in the database, 76% traveled for the purpose of tourism, 10% for business, 3% to VFR, and 11% for other reasons such as education, missionary work, research, or volunteering. Tourists were disproportionately represented among travelers receiving environmental diagnoses such as altitude illness (99.5%), exposure-related illnesses (89%), injuries (84%), and bites (81%) (Table 3). Those traveling for business, VFR, or other reasons were thus underrepresented across all categories of environmental illness (Table 3).
Table 3. Purpose of travel data for travelers to Nepal
|All travelers (10,461)||7,935 (75.9)||1,029 (9.8)||329 (3.1)||1,168 (11.2)|
|All environment-related illness (2,046)||1,806 (88.3)†,‡||91 (4.4)||32 (1.6)||117 (5.7)|
|Injuries (783)||654 (83.5)§||58 (7.4)||14 (1.8)||57 (7.3)|
|Altitude illness (610)||607 (99.5)‖||2 (0.3)||1 (0.2)||—|
|Bites (422)||340 (80.6)¶||18 (4.3)||16 (3.8)||48 (11.4)|
|Exposure-related conditions (231)||205 (88.7)#||13 (5.6)||1 (0.4)||12 (5.2)|
Sixty percent of all travelers assessed and diagnosed at CIWEC during the study period had sought pre-travel advice prior to departure. Travelers who were diagnosed with an environment-related illness were, in general, less likely than other travelers to have sought pre-travel advice (χ2= 4.7, p= 0.03, OR: 0.9, 95% CI: 0.8–1.0). Specifically, those who were diagnosed with injuries or exposure-related illness were less likely than other travelers to have obtained pre-travel information from a clinician (χ2= 8.9, p= 0.003, OR: 0.8, 95% CI: 0.7–0.9 and χ2= 4.9, p= 0.027, OR: 0.7, 95% CI: 0.6–1.0, respectively). Interestingly, travelers who sustained a bite or required rabies PEP were more likely than other travelers to have sought pre-travel advice (χ2= 12.2, p < 0.001, OR: 1.6, 95% CI: 1.2–2.0).
In multivariate analysis, independent variables such as male gender (p < 0.001), traveling for the purpose of tourism (p < 0.001), and a lack of pre-travel advice (p= 0.043) were associated with an environment-related illness among travelers. Similarly, independent risk factors for “altitude”-related diagnoses in travelers included male gender (p < 0.001), traveling for the purpose of tourism (p < 0.001), and age (p < 0.001), as predicted by the regression model.
In this study, we examined environment-related injuries and illness in over 10,000 travelers and 4,000 expatriates presenting to a large travel clinic in Kathmandu, Nepal. Injuries, high-altitude illness, bites, and exposure-related conditions were common, accounting for 17% of diagnoses given to travelers presenting to CIWEC over the study period, and 9% of diagnoses given to expatriates. To our knowledge, this is the first study to profile environmental hazards and their related illnesses in a large group of travelers and expatriates in Nepal, and to evaluate independent risk factors for these conditions.
Injuries account for the greatest burden of disability worldwide, and they are the leading cause of preventable deaths in travelers.19 Trauma accounts for up to one quarter of deaths associated with travel,20,21 a rate that is much higher than for nontravelers.21,22 Nonfatal injuries among travelers are also widely reported23,24 and occur at rates beyond what would be expected in the local population.25,26 In this study, tourists were overrepresented among travelers sustaining injuries, though we did not observe a gender bias, which contrasts with previous reports of a male preponderance among injured travelers.23,25 Our findings support previous studies, which report lacerations and fractures to be the most common nonfatal injuries sustained by tourists.24 That travelers who sustained injuries were less likely than other travelers to have obtained pre-travel advice suggests that we are failing to reach this specific group, which may benefit from targeted pre-travel intervention.
It is well recognized that tourists are at risk of injuries due to their avid participation in sports or leisure activities, and lack familiarity with their environment,27,28 while nontourists are more likely to sustain home-based injuries.5 It is therefore surprising that expatriates in this study were almost twice as likely as travelers to sustain a head injury. However, the study design did not allow us to capture predisposing circumstances and risk factors that might better explain this discrepancy. We have no way of knowing, for instance, if some or all of these head injuries were motor vehicle related, or secondary to falls, or related to sports activities. Future studies that better elucidate the burden of head injuries in expatriates would be informative.
High-altitude illness was another common group of environmental diagnoses among travelers, though it occurred rarely in expatriates, suggesting that this latter population comprised long-term residents who are either well acclimated or alternatively are less likely to travel to high altitude than travelers and tourists. Factors independently associated with altitude diagnoses among travelers were male gender, traveling for the purpose of tourism, and older age. These findings support previous research, suggesting that HAPE is more common in males,29 though contrast with the widely held convention that increasing age confers protection against AMS.29,30 That increasing age was independently associated with altitude diagnoses must be interpreted cautiously, as denominator data on the age distribution of trekkers in Nepal are lacking. The possibility that trekkers were, in general, older than other tourists arriving in Nepal cannot be ruled out.
That AMS was the least commonly diagnosed altitude-spectrum disorder mainly reflects the subjectively mild, tolerable, and reversible nature of symptoms resulting in fewer travelers seeking medical attention, especially once they have descended to the low altitude of Kathmandu. Other factors such as increased awareness and vigilance on the part of trekkers or increased use of prophylactic acetazolamide may also play a role.31 The number of cases of AMS in this study is likely an underestimate of the true incidence of this entity, which is reported to occur in approximately 30% to 50% of trekkers hiking to 4,000 m,29,32 and up to 84% of people who fly directly to 3,800 m in Nepal.33 As high-altitude illness is largely preventable, and potentially life threatening, continued attempts to educate travelers, particularly tourists engaging in treks, are warranted.34 Adverse outcomes in high-altitude illness underscore the importance of acclimatization, ascent avoidance until symptom abatement, medical intervention, and descent if no improvement in symptoms at the same altitude or at the first indication of HACE or HAPE.6,8,10
Bites from wild or domesticated animals represent another health risk to travelers. In Kathmandu, there is a large population of semiferal dogs that are known to transmit rabies.14 In addition, monkeys reside in and around temples that are popular with tourists of Nepal, and they too, pose a theoretical risk of rabies transmission as well as other zoonotic infections. The majority of animal bites sustained by travelers and expatriates in this study were delivered by dogs (68 and 77%, respectively). Expatriates have been documented to have a higher risk estimate for dog bites because they are more likely to own pets, visit others with pets, and adopt stray animals.14 While the administration of rabies preexposure immunization to travelers remains controversial, with little empiric evidence to guide the clinician,14 expatriates are one group for whom the benefits of this intervention are likely to outweigh the costs. Monkey bites, while less frequent, were 13 times more likely to occur in tourists than expatriates, suggesting that tourists pursue activities with greater potential for human–monkey interaction. An additional 21 individuals suffered monkey scratches, which also pose a smaller but significant risk for disease transmission.
Tourists can greatly reduce their risk of exposure to rabies by adhering to a strict no-contact policy with wild or free-roaming animals and exercising common sense. That travelers who sought pre-travel advice were more likely than others to sustain animal bites or require rabies PEP is surprising, and suggests that while we may be reaching this target group, the desired educational impact is not being achieved. An alternate explanation is that the travelers who sought pre-travel advice were the ones to seek care after a bite and may therefore have been overrepresented. That younger travelers were overrepresented among those sustaining bite wounds or requiring rabies PEP is also supported by an analysis of over 300 bites in returned travelers.18 In their study, Gautret and colleagues further discovered a gender bias among recipients of bite wounds, with females overrepresented. Our results demonstrate an insignificant gender bias.
This study has a number of limitations. First, the CIWEC clinic represents one center servicing primarily Western travelers and expatriates in Kathmandu and the surrounding area; thus, the population described herein may differ from other traveling and expatriate populations, and those seen elsewhere in Nepal. Second, as Nepal is geographically and climatologically unique, the burden of environment-related illness seen in this study may not be generalizable to other locations. Third, it is likely that travelers incurring minor injuries or exposure-related illness would fail to seek medical attention; thus, our numbers likely represent an underestimate of these minor diseases. Fourth, this study did not evaluate factors that may influence the burden of environmental disease, such as prevalence of AMS prophylaxis, specific climatologic data (temperatures and rainfall), or activities antecedent to injury. Finally, without current denominator data, our ability to draw conclusions about risk estimates and incidence of environmental hazards in travelers is limited.
In summary, travelers and expatriates in Nepal are vulnerable to a variety of environmental hazards and their related illnesses, including injuries, high altitude sickness, bites, and climate-related exposures. Factors independently associated with environment-related conditions include male gender, a lack of pre-travel advice, and traveling for tourism, while high-altitude illness is correlated with male gender, traveling for tourism, and older age. The inverse relationship between environment-related diagnoses and pre-travel advice likely reflects a knowledge gap on the part of travelers, which is potentially amenable to intervention. The increasing popularity of adventure travel to developing countries combined with the risk of potentially life-threatening illnesses necessitates targeted education for these individuals in a pre-travel setting.
GeoSentinel: the Global Surveillance Network of the International Society of Travel Medicine is supported by Cooperative Agreement U50/CCU412347 from the Centers for Disease Control and Prevention. This research was also supported through the Canadian Institutes for Health Research (MT-13721, K. C. K.) and the McLaughlin-Rotman Center for Global Health (K. C. K.).
Declaration of interests
The authors state that they have no conflicts of interest.