Climate change and infectious disease research in Nepal: Are the available prerequisites supportive enough to researchers?

Available online 10 January 2020Although Nepal has been identified as a country highly vulnerable to adverse health and socioeconomic impacts arising from climate change, extant research on climate sensitive infectious diseases has yet to develop the evidence base to adequately address these threats. In this opinion paper we identify and characterise basic requirements that are hindering the progress of climate change and infectious disease research in Nepal. Our opinion is that immediate attention should be given to strengthening Nepal's public health surveillance system, promoting inter-sectoral collaboration, improving public health capacity, and enhancing community engagement in disease surveillance. Moreover, we advocate for greater technical support of public health researchers, and data sharing among data custodians and epidemiologists/researchers, to generate salient evidence to guide relevant public health policy formulation aimed at addressing the impacts of climate change on human health in Nepal. International studies on climate variability and infectious diseases have clearly demonstrated that climate sensitive diseases, namely vector-borne and food/water-borne diseases, are sensitive to climate variation and climate change. This research has driven the development and implementation of climate-based early warning systems for preventing potential outbreaks of climate-sensitive infectious diseases across many European and African countries. Similarly, we postulate that Nepal would greatly benefit from a climate-based early warning system, which would assist in identification or prediction of conditions suitable for disease emergence and facilitate a timely response to reduce mortality and morbidity during epidemics.Dinesh Bhandari, Peng Bi, Jeevan Bahadur Sherchand, Meghnath Dhimal, Scott Hanson-Ease

Non-linear effect of temperature variation on childhood rotavirus infection: A time series study from Kathmandu, Nepal

Available online 30 July 2020Introduction: This study aimed to investigate the effects of temperature variability on rotavirus infections among children under 5 years of age in Kathmandu, Nepal. Findings may informinfection control planning, especially in relation to the role of environmental factors in the transmission of rotavirus infection. Methods: Generalized linear Poisson regression equationswith distributed lag non-linearmodelwere fitted to estimate the effect of temperature (maximum,mean and minimum) variation onweekly counts of rotavirus infections among children under 5 years of age living in Kathmandu, Nepal, over the study period (2013 to 2016). Seasonality and long-term effects were adjusted in the model using Fourier terms up to the seventh harmonic and a time function, respectively. We further adjusted the model for the confounding effects of rainfall and relative humidity. Results: During the study period, a total of 733 cases of rotavirus infection were recorded, with amean of 3 cases per week. We detected an inverse non-linear association between rotavirus infection and average weekly mean temperature, with increased risk (RR: 1.52; 95% CI: 1.08–2.15) at the lower quantile (10th percentile) and decreased risk (RR: 0.64; 95% CI: 0.43–0.95) at the higher quantile (75th percentile). Similarly, we detected an increased risk [(RR: 1.93; 95% CI: 1.40–2.65) and (RR: 1.42; 95% CI: 1.04–1.95)] of rotavirus infection for both maximum and minimum temperature at their lower quantile (10th percentile). We estimated that 344 (47.01%) cases of rotavirus diarrhoea among the children under 5 years of age were attributable to minimum temperature. The significant effect of temperature on rotavirus infectionwas not observed beyond lag zero week. Conclusion: An inverse non-linear association was estimated between rotavirus incidence and all three indices of temperature, indicating a higher risk of infection during the cooler times of the year, and suggesting that transmission of rotavirus in Kathmandu, Nepal may be influenced by temperature.Dinesh Bhandari, Peng Bi, Meghnath Dhimal, Jeevan Bahadur Sherchand, Scott Hanson-Ease

Prevalence of Arcobacter and other pathogenic bacteria in river water in Nepal

Published: 10 July 2019This study aims to determine the diversity of pathogenic bacteria in the Bagmati River, Nepal, during a one-year period. A total of 18 river water samples were collected from three sites (n = 6 per site) along the river. Bacterial DNA, which were extracted from the water samples, were analyzed for bacterial 16S rRNA genes by next-generation sequencing for 13 of 18 samples, and by quantitative PCR targeting Arcobacter for all 18 samples. The 16S rRNA sequencing identified an average of 97,412 ± 35,909 sequences/sample, which were then categorized into 28 phyla, 61 classes, and 709 bacterial genera. Eighteen (16%) genera of 111 potential pathogenic bacteria were detected with abundance ratios of >1%; Arcobacter, Acinetobacter, and Prevotella were the dominant genera. The Arcobacter abundance ratios were 28.6% (n = 1), 31.3 ± 15.8% (n = 6), and 31.8 ± 17.2% (n = 6) at the upstream, midstream, and downstream sites, respectively. Arcobacter was detected in 14 (78%) of 18 samples tested, with concentrations ranging from 6.7 to 10.7 log10 copies/100 mL, based on quantitative PCR. Our results demonstrate the poor bacterial quality of the Bagmati River water, suggesting a need for implementing more measures to reduce fecal contamination in the river water.Rajani Ghaju Shrestha, Sarmila Tandukar, Dinesh Bhandari, Samendra P. Sherchan, Yasuhiro Tanaka, Jeevan B. Sherchand and Eiji Haramot

Gut microbiome transition across a lifestyle gradient in Himalaya

Published: November 15, 2018The composition of the gut microbiome in industrialized populations differs from those living traditional lifestyles. However, it has been difficult to separate the contributions of human genetic and geographic factors from lifestyle. Whether shifts away from the foraging lifestyle that characterize much of humanity's past influence the gut microbiome, and to what degree, remains unclear. Here, we characterize the stool bacterial composition of four Himalayan populations to investigate how the gut community changes in response to shifts in traditional human lifestyles. These groups led seminomadic hunting-gathering lifestyles until transitioning to varying levels of agricultural dependence upon farming. The Tharu began farming 250-300 years ago, the Raute and Raji transitioned 30-40 years ago, and the Chepang retain many aspects of a foraging lifestyle. We assess the contributions of dietary and environmental factors on their gut-associated microbes and find that differences in the lifestyles of Himalayan foragers and farmers are strongly correlated with microbial community variation. Furthermore, the gut microbiomes of all four traditional Himalayan populations are distinct from that of the Americans, indicating that industrialization may further exacerbate differences in the gut community. The Chepang foragers harbor an elevated abundance of taxa associated with foragers around the world. Conversely, the gut microbiomes of the populations that have transitioned to farming are more similar to those of Americans, with agricultural dependence and several associated lifestyle and environmental factors correlating with the extent of microbiome divergence from the foraging population. The gut microbiomes of Raute and Raji reveal an intermediate state between the Chepang and Tharu, indicating that divergence from a stereotypical foraging microbiome can occur within a single generation. Our results also show that environmental factors such as drinking water source and solid cooking fuel are significantly associated with the gut microbiome. Despite the pronounced differences in gut bacterial composition across populations, we found little differences in alpha diversity across lifestyles. These findings in genetically similar populations living in the same geographical region establish the key role of lifestyle in determining human gut microbiome composition and point to the next challenging steps of determining how large-scale gut microbiome reconfiguration impacts human biology.Aashish R. Jha, Emily R. Davenport, Yoshina Gautam, Dinesh Bhandari, Sarmila Tandukar, Katharine M. Ng, Gabriela K. Fragiadakis, Susan Holmes, Guru Prasad Gautam, Jeff Leach, Jeevan Bahadur Sherchand, Carlos D. Bustamante, Justin L. Sonnenbur

Assessing the effect of climate factors on childhood diarrhoea burden in Kathmandu, Nepal

Introduction: This study was undertaken to assess the effect of climate variability on diarrhoeal disease burden among children under 5 years of age living in Kathmandu, Nepal. The researchers sought to predict future risk of childhood diarrhoea under different climate change scenarios to advance the evidence base available to public health decision-makers, and the Nepalese infection control division, in planning for climate impacts. Methods: A time series study was conducted using the monthly case count of diarrhoeal disease (2003–2013) among children under 5 years of age living in Kathmandu, Nepal. A quasi Poisson generalised linear equation with distributed lag linear model was fitted to estimate the lagged effect of monthly maximum temperature and rainfall on childhood diarrhoea. The environmental framework of comparative risk assessment was used to assess the environmental burden of diarrhoea within this population. Results: A total of 219,774 cases of diarrhoeal disease were recorded during the study period with a median value of 1286 cases per month. The results of a regression model revealed that the monthly count of diarrhoea cases increased by 8.1% (RR: 1.081; 95% CI: 1.02–1.14) per 1 °C increase in maximum temperature above the monthly average recorded within that month. Similarly, rainfall was found to have significant effect on the monthly diarrhoea count, with a 0.9% (RR; 1.009; 95% CI: 1.004–1.015) increase in cases for every 10mm increase in rainfall above the monthly cumulative value recorded within that month. It was estimated that 7.5% (95% CI: 2.2%–12.5%) of the current burden of diarrhoea among children under 5 years of age could be attributed to climatic factors (maximum temperature), and projected that 1357 (UI: 410–2274) additional cases of childhood diarrhoea could be climate attributable by the year 2050 under low-risk scenario (0.9 °C increase in maximum temperature). Conclusion: It is estimated that there exists a significant association (p < 0.05) between childhood diarrhoea and an increase in maximum temperature and rainfall in Kathmandu, Nepal. The findings of this study may inform the conceptualization and design of early warning systems for the prediction and control of childhood diarrhoea, based upon the observed pattern of climate change in Kathmandu.Dinesh Bhandaria, Peng Bia, Jeevan Bahadur Sherchandb, Meghnath Dhimalc, Scott Hanson-Easey

Cyclospora infection among school children in Kathmandu, Nepal: Prevalence and associated risk factors

Published online 20 August, 2015Background: The intestinal coccidian protozoa Cyclospora cayetanensis has emerged as an important cause of parasitic diarrhea among children living in developing countries. This study aimed to determine the prevalence of Cyclospora among the school children of Kathmandu with reference to various associated risk factors. Methodology: A total of five hundred and seven stool samples from students between the age of 3–14 years, studying in 13 different schools in Kathmandu were collected during the study period (May–November, 2014) and processed at the Public Health Research Laboratory, Institute of Medicine, Kathmandu, Nepal. A modified acid fast staining technique (Kinyoun’s method) was used to detect oocyst of Cyclospora from the formal-ether concentrated stool samples. Results: Cyclospora was detected in 3.94% (20/507) of the stool samples examined. The prevalence was found to be highest among the students in the 3–5 year age group i.e. 10.15% (13/128), peaking during the rainy season (June–August). The detection rate was found to be significantly higher (p < 0.05) among children presenting with diarrheal symptoms, household keeping livestock and consumers of raw vegetables/fruits, showing a prevalence of 10.57% (11/104), 10.11% (9/89) and 7.25% (14/193) respectively. Conclusion: Consumption of untreated drinking water, fresh produce (raw fruits/vegetables) without proper washing and the presence of livestock at home were found to be predisposing factors for higher susceptibility of infection due to Cyclospora. This finding confirms the existence of a public-health issue with potentially serious consequences whereby children can be infected through exposure to oocysts in contaminated food and water and get ill as a result.Dinesh Bhandari, Sarmila Tandukar, Hiramani Parajuli, Pratigya Thapa, Prakash Chaudhary, Dhiraj Shrestha, Pradeep K Shah, Jatan B Sherchan and Jeevan B Sherchan

Prevalence and determinants of hypertension in underrepresented indigenous populations of Nepal

Published: February 18, 2022Indigenous populations residing in low- and middle-income countries (LMICs) are highly underrepresented in medicine and public health research. Specifically, data on non-communicable diseases (NCDs) from indigenous populations remains scarce. Despite the increasing burden of NCDs in the Himalayan region, their prevalence in many indigenous populations remains understudied. The nationally representative public health surveys often do not include the indigenous communities, especially those that reside in rural areas or exist in small numbers. This observational cross-sectional survey study aimed to assess the prevalence of three NCD risk factors namely obesity, hypertension, and tachycardia and identify dietary and lifestyle variables associated with them across underrepresented indigenous populations of Nepal. A total of 311 individuals (53.3% women, 46.7% men) with mean age 43±15 years from 12 indigenous Nepali communities residing in rural (47.9%) or semi-urban (52.1%) areas volunteered to participate in this study. Univariate tests and multivariable logistic regressions were used to analyze the survey data. The mean systolic and diastolic blood pressures were 121.3±19.5 mmHg and 81.3±11.8 mmHg respectively. Overall, the prevalence of obesity and tachycardia was low (0.64% and 3.22%, respectively) but hypertension was prevalent at 23.8%. Hypertension was not significantly different across populations, but it was associated with age, BMI, and tobacco use, and collectively, these variables explained 13.9% variation in hypertension prevalence. Although we were unable to detect direct associations between individual determinants of hypertension identified in non-indigenous Nepalis, such as education levels, alcohol consumption, and smoking in this study, having one or more determinants increased the odds of hypertension in the indigenous participants. Furthermore, ~14% of the hypertensive individuals had none of the universally identified hypertension risk factors. The lack of association between previously identified risk factors for hypertension in these individuals indicates that the additional determinants of hypertension remain to be identified in indigenous Nepali populations.Tsedenia Workneh Denekew, Yoshina Gautam, Dinesh Bhandari, Guru Prasad Gautam, Jeevan Bahadur Sherchand, Amod K. Pokhrel, Aashish R. Jh

Co-infection by waterborne enteric viruses in children with gastroenteritis in Nepal

Enteric viruses are highly contagious and a major cause of waterborne gastroenteritis in children younger than five years of age in developing world. This study examined the prevalence of enteric virus infection in children with gastroenteritis to identify risk factors for co-infections. In total, 107 stool samples were collected from patients with acute gastroenteritis along with samples of their household drinking water and other possible contamination sources, such as food and hand. The presence of major gastroenteritis-causing enteric virus species (group A rotaviruses, enteroviruses, adenoviruses, and noroviruses of genogroup I) in stool and water samples was examined using quantitative polymerase chain reaction. Among the 107 stool samples tested, 103 (96%) samples contained at least one of the four tested enteric viruses, and the combination of group A rotaviruses and enteroviruses was the most common co-infection (52%, n = 54/103). At least one viral agent was detected in 16 (16%) of 103 drinking water samples. Identical enteric viruses were detected in both the stool and water samples taken from the same patients in 13% of cases (n = 13/103). Group A rotaviruses were most frequently found in children suffering from acute diarrhea. No socio-demographic and clinical factors were associated with the risk of co-infection compared with mono-infection. These less commonly diagnosed viral etiological agents in hospitals are highly prevalent in patients with acute gastroenteritis.Sarmila Tandukar, Jeevan B. Sherchand, Surendra Karki, Bikash Malla, Rajani Ghaju Shrestha, Dinesh Bhandari, Ocean Thakali and Eiji Haramot