Analysis of local drinking water for fecal contamination in Solu-Khumbu / Mt. Everest region, Nepal

Nepalese doctors raised ongoing concerns regarding the high incidence of diarrhea experienced by the tourists and Nepali in the popular Solu-Khumbu region of the Nepal Himalayas (Dr. Kami Sherpa, Khunde/Solu-Khumbu, Nepal; personal communication). This observation of local physicians is in accordance with studies about traveller's diarrhea in remote regions (survey in (Adler et al., 2022)). The area gives access to some of the world's highest mountains including Mount Everest, Nuptse, Lhotse and others, and since 1979 is a World Natural Heritage Site. However, Nepal's urban and rural areas lack basic water treatment facilities and there is poor sanitation in spite of some improvements (Nicholson et al., 2016), (Maharjan et al., 2018), (Murphy and Pandey 2012). Open defecation and sewage waste are often discharged directly into streams or rivers (Nicholson et al., 2016). Most waterborne bacterial pathogens that are potentially introduced into drinking water supplies come via animal or human feces (WHO 2011). These bacteria do not grow in the water, but initiate infection once consumed and in the gastrointestinal tract, and then the feces of these infected humans or animals can then potentially repeat this disease cycle (WHO 2011). Increased tourism to the popular trekking trails in Solu-Khumbu contributes to this cycle, and this may additionally pollute water supplies (ie discarded non-biodegradable bottles or batteries (Nicholson et al., 2016), (Murphy and Pandey 2012)). All drinking water sources should be carefully and regularly monitored and managed to protect public health and to secure future sustainability (Nicholson et al., 2016), (Maharjan et al., 2018), (Murphy and Pandey 2012), (WHO 2011).

Epidemiological data from Nepal strongly suggests that fecal contamination of water sources remains a key problem causing diarrheal infections (Nicholson et al., 2016), (Maharjan et al., 2018), (Ansari et al., 2012), (Murphy and Pandey 2012), (WHO 2011). Although diarrhea is often reported as traveller's diarrhea and affects about two thirds of visitors, it is even more a problem for the locals, especially children (Ansari et al., 2012). In Nepal, 30,000 children die every year due to diarrhea ((anonymous) 2019). The under 5-mortality rate in 2012 in Nepal was 42 per 1000 live births (Lamichhane et al., 2017), (Budhathoki et al., 2016) and about 25% of all deaths before the age of 5 are caused by diarrhea (Ansari et al., 2012).

Diarrheal diseases were the fifth leading cause of all Nepali deaths from 1990 to 2017 at 36.12% ((anonymous) 2019). Improvements in sanitation, personal hygiene and water quality are the most important factors to save life (Acharya et al., 2013), to control outbreaks (Kilian 1983), (Lawin and Scherer 1981) and may even avoid epidemic outbreaks as it has happened with typhoid fever in Kathmandu (Karkey et al., 2008), (Basnyat 2015).

Waterborne transmission of human diseases varies in severity from mild gastroenteritis to severe, even fatal, diarrhea, dysentery, hepatitis and typhoid fever (WHO 2011). Different pathogens may cause gastroenteritis (DuPont et al., 2009), (Adachi et al., 2007), (Murphy and Pandey 2012). The most common bacterial infections are caused by Escherichia coli, Campylobacter species, Salmonella, Shigella and V. cholerae. Viral gastroenteritis is often due to infections involving adeno-, rota- or norovirus. Protozoa parasites like Giardia lamblia, Entamoeba histolytica or Cryptosporidia can also cause intestinal problems. In Southeast Asia, especially Nepal, Campylobacter sp. is the most common pathogen causing diarrhea (Pandey et al., 2011). However, since a shift of pathogens was observed recently in several countries worldwide such data is preliminary and continuous epidemiological research is necessary (Adler et al., 2022), (Murphy et al., 2019).

Some severe cases will require antibiotics like azithromycin (Steffen et al., 2015) but the most important therapy in most cases is adequate administration of fluid to avoid dehydration. However, this can be challenging, even critical, where there is no safe drinking water. Several germs in South East Asia have recently changed their resistance profile against antimicrobial drugs (Singh and Mustapha 2013). It should be noted that fluorquinolones which are first-choice drug for traveller's diarrhea in many countries should not be used in South-East Asia, especially Nepal and India, because of the high rate of resistance here, e.g. Camphylobacter 97%, Shigella 78%, and Enterotoxic Escherichia coli (ETEC) 73% (Adler et al., 2022), (Riddle et al., 2021), (Guiral et al., 2019), (Tribble 2017), (Riddle et al., 2017), (Singh and Mustapha 2013), (Pandey et al., 2011)

The survival of pathogens in water differs widely from hours (Shigella (Schreiber 1981; Singh and McFeters 1990), (Backer 2007)) or weeks (E. coli, Campylobacter (Singh and McFeters 1990), (Backer 2007), ((anonymous) 2018) to months (Giardia lamblia cysts (Backer 2007) (deRegnier, Cole et al. 1989),) or to even more than a year (Hepatitis A, polio virus (Backer 2007) (Biziagos et al., 1988),) and depends on the physiochemical condition of the water (McFeters and Terzieva 1991), (Wang and Doyle 1998). However, according to WHO recommendations water should be investigated for thermotolerant coliform bacteria as indicator of germs from recent fecal contamination as this presents the possibility of a transmission of waterborne diarrheal diseases ((anonymous) 2011), (Nicholson et al., 2016), (Farnleitner et al., 2010).

The settlements and villages of the Solo Khumbu region obtain their water directly from different sources including open waterholes, creeks coming down the mountains, or at sources located directly in the village that are sometimes also accessible to animals (e.g. yaks) which may defecate in this water supply (Fig. 1). The location of the primary water source may be close by or travel great distances via exposed tubing as at Gorak Shep (approximately 1800m). Exposed tubes present additional problems as the water can often freeze, and no one is controlling the development of biofilm in a tube several kilometers long.

Contamination of water sources has mostly a shortterm impact on tourists and a long-term influence on the local people and economy. Therefore the topic is relevant for both, travelers and local people. According to the Central Bureau of Statistics there was a total of 4980 households with 20,399 persons living in the Solu-Khumbu District in 2011 (https://cbs.gov.np/population-2011; 6.7.2022), of which about 3,500 were living in the Solu-Khumbu Valley (45.6/km2). With some variations induced by political reasons, corona-related travel restrictions etc. the region takes an additional seasonal “load” of about 60,000 visitors (https://snp.gov.np/tourism; 6.7.2022).

The first aim of this study was to analyze the primary drinking water sources for fecal contamination from as many water sources as possible in the popular trekking area of Solo Khumbu region, Nepal. The second aim emerged during the study in Nepal: bacterial analyses of water ready to use. In Solu-Khumbu this is normally water stored in canisters in houses or lodges.

留言 (0)

沒有登入
gif