Dehydration and malaria augment the risk of developing chronic kidney disease in Sri Lanka

Climate change and its influence in nephron mass

PURPOSE OF REVIEW

The consequences of climate change, including heat and extreme weather events impact kidney function in adults and children. The impacts of climate change on kidney development during gestation and thereby on kidney function later in life have been poorly described. Clinical evidence is summarized to highlight possible associations between climate change and nephron mass.

RECENT FINDINGS

Pregnant women are vulnerable to the effects of climate change, being less able to thermoregulate, more sensitive to the effects of dehydration, and more susceptible to infections. Exposure to heat, wildfire smoke, drought, floods and climate-related infections are associated with low birth weight, preterm birth and preeclampsia. These factors are associated with reduced nephron numbers, kidney dysfunction and higher blood pressures in offspring in later life. Exposure to air pollution is associated with higher blood pressures in children and has variable effects on estimated glomerular filtration rate.

SUMMARY

Climate change has important impacts on pregnant women and their unborn children. Being born too small or too soon is associated with life-time risk of kidney disease. Climate change may therefore have a dual effect of impacting fetal kidney development and contributing to cumulative postnatal kidney injury. The impact on population kidney health of future generations may be significant.

Risky working conditions and chronic kidney disease

BACKGROUND

Individuals in the workplace are exposed to various environments, tasks, and schedules. Previous studies have indicated a link between occupational exposures and an increased risk of chronic kidney disease (CKD). However, the social conditions of the work environment may also be a crucial contributing factor to CKD. Furthermore, individuals may encounter multiple occupational-related risk factors simultaneously, underscoring the importance of investigating the joint risk of different working conditions on CKD.

METHODS

A prospective analysis of 65,069 UK Biobank participants aged 40 to 69 years without CKD at baseline (2006-2010) was performed. A self-administered questionnaire assessed working conditions and a working conditions risk score were developed. Participants who answered "sometimes" or "often" exposure to occupational heat or occupational secondhand cigarette smoke; involved in shift work or heavy workloads ("usually" or "always"), were grouped as high-risk working conditions. Each working condition was scored as 1 if grouped as high-risk, and 0 if not. The working conditions risk score was equal to the sum of these four working conditions. Cox proportional hazard regression models were used to estimate the associations between working conditions and CKD incidence.

RESULTS

The mean follow-up time was 6.7 years. After adjusting for demographic, lifestyle, and working time factors, the hazard ratios for the development of CKD for heavy workloads, shift work, occupational secondhand cigarette smoke exposure, and occupational heat exposure were 1.24 (95%CI = 1.03, 1.51), 1.33 (95%CI = 1.10, 1.62), 1.13 (95%CI = 1.01, 1.26), 1.11 (95%CI = 0.99, 1.24), respectively. The risk of CKD was found to be significantly associated with an increasing working conditions risk score. Individuals with a working conditions risk score of 4 had an 88.0% (95% CI = 1.05, 3.35) higher risk of developing CKD when compared to those with a working conditions risk score of 0.

CONCLUSIONS

Adverse working conditions, particularly when considered in combination, can significantly elevate the risk of chronic kidney disease (CKD). These results provide a reference for implementing measures to prevent CKD.

Kidney disease characteristics, prevalence, and risk factors in León, Nicaragua: a population-based study

BACKGROUND

CKD of unknown etiology (CKDu) disproportionately affects young people in Central America who lack traditional CKD risk factors (diabetes and hypertension) and has instead been variably linked to heat stress, occupational and environmental exposures, nephrotoxic medications, and/or genetic susceptibility. This study aimed to estimate the prevalence of CKD and identify risk factors for traditional CKD and CKDu in Nicaragua.

METHODS

Surveys and assessment for CKD markers in urine and serum were performed in 15-59 year olds in households of the León municipality of Nicaragua. The survey included questions on demographics, health behaviors, occupation, and medical history. Participants with CKD were subdivided into traditional CKD and suspected CKDu based on history of diabetes, hypertension, or other specified conditions. A multinomial logistic regression model was used to identify factors associated with traditional CKD and suspected CKDu, compared to the non-CKD reference group.

RESULTS

In 1795 study participants, CKD prevalence was 8.6%. Prevalence in males was twofold higher than females (12% vs 6%). Of those with CKD, 35% had suspected CKDu. Both traditional CKD and CKDu were associated with male sex and increasing age. Traditional CKD was associated with a family history of CKD, history of urinary tract infections, and lower socioeconomic status, while CKDu was associated with drinking well water and a lower body mass index.

CONCLUSIONS

Both traditional CKD and CKDu are significant burdens in this region. Our study supports previous hypotheses of CKDu etiology and emphasizes the importance of CKD screening.

Prevalence of Chronic Kidney Disease of Uncertain Etiology Within Selected Farming Communities in Rural Sri Lanka

Background

Chronic kidney disease of uncertain etiology (CKDu) is an emergent health concern, particularly in tropical farming communities in several global hotspots, including Sri Lanka. This particular nephropathy is characterized by a progressive decline in kidney function in the absence of conventional chronic kidney disease (CKD) risk factors such as diabetes mellitus, hypertension, and other identifiable kidney disorders. As it is almost asymptomatic at early stages, CKDu is mostly diagnosed at late stages with significant kidney damage. Hence, the identification of disease susceptibility and vulnerable communities at the earliest possible instances is highly important for the management of the disease.

Objective

We aimed to compare kidney health across three different farming communities in Sri Lanka to identify CKDu susceptibilities.

Methods

A cross-sectional study was performed with three selected farming communities: paddy farmers (PF; N = 581), sugarcane farmers (SF; N = 550), and vegetable farmers (VF; N = 244) in comparison with an age-matched control group of nonfarming (NF; N = 225) individuals. A medical examination was performed to investigate health status and medical history, whereas a urinalysis was performed to determine creatinine and albumin contents. Estimated glomerular filtration rate (eGFR) and urinary albumin-creatinine ratio (ACR) were used for assessment of kidney function. CKDu susceptibility was determined based on eGFR, and urinary ACR adhering to the clinical practice guidelines in Sri Lanka.

Results

The median (interquartile range [IQR]) eGFR levels of PF (85 mL/min/1.73 m2 [72-97]) and SF (93 mL/min/1.73 m2 [73-112]) were significantly lower than that of the NF group (103 mL/min/1.73 m2 [87-125]) (P < .0001), whereas eGFR of VF (100 mL/min/1.73 m2 [80-111]) was not significantly different compared with NF. The median (IQR) urinary ACR levels of the study groups, PF, SF, VF, and NF, were 0.59 (0.26-1.45), 0.46 (0.28-0.88), 0.45 (0.34-0.90), and 0.44 (0.34-1.02) mg/mmol, respectively. However, urinary ACR did not differ significantly across the study groups (P > .05). The prevalence of CKDu within PF (13.60%), SF (12.54%), and VF (6.67%) communities was significantly higher (P < .05) compared with the NF (2.67%). Of the total CKD cases, CKDu susceptible cases represented 73%, 69%, 50%, and 25% in PF, SF, VF, and NF, respectively, indicating a high risk of CKDu susceptibility among farming communities. Moreover, a noteworthy association of CKDu was observed with agrochemical exposure (odds ratio [OR] = 3.11, 95% confidence interval [CI] = 1.36-7.09). Concerning the farming practices, sugarcane farming showed the highest association with CKDu prevalence (OR = 3.40, 95% CI = 1.49-7.78).

Conclusions

Compared with the nonfarming group, a significant risk of CKDu was observed in the three farming communities, particularly among paddy and sugarcane farmers. Longitudinal epidemiological studies to identify vulnerable farming communities and associated risk factors are critically needed to develop effective management strategies against CKDu within farming communities.

Chronic Tubulointerstitial Nephropathy of Agricultural Communities

Chronic interstitial nephritis in agricultural communities is an emerging public health concern affecting numerous agricultural communities in tropical countries, including regions in India, with a significant impact on the health and well-being of affected individuals. The affected individuals suffer from various psychosocial, nutritional, and metabolic challenges due to organ failure, which affects their quality of life. The etiology remains poorly understood, and various risk factors, which include various environmental and occupational hazards, have been implicated in its development. The recent discovery of lysosomal proximal tubulopathy has reignited interest in its pathogenesis. Along with the representative feature of chronic interstitial nephritis, changes suggestive of tubular injury have also been reported. It is suggested to use the term “chronic tubulointerstitial nephropathy of agricultural community” instead of chronic interstitial nephritis of the agricultural communities. Chronic tubulointerstitial nephropathy in agricultural communities is a slowly progressive disease that initially does not cause any symptoms in patients and most patients have a delayed onset of symptoms. Several diagnostic criteria have been introduced over the past years and one introduced by the Ministry of Health of Sri Lanka is widely used. The management of this chronic illness is no different from other causes of chronic interstitial nephritis and our focus should be on implementing various preventive strategies to reduce its incidence in agricultural communities and protect the health and well-being of agricultural workers. By disseminating knowledge about chronic tubulointerstitial nephropathy in agricultural communities, we can contribute to the development of evidence-based interventions to reduce the burden of the disease on affected communities. Moreover, we would like to sensitize physicians to this entity to increase awareness and identify potential endemic areas in various agricultural communities.

Factors Associated with Chronic Kidney Disease of Unknown Etiology (CKDu): A Systematic Review

(1) Background: Despite ample research, the factors, specific causes, and pathways associated with chronic kidney disease of unknown etiology (CKDu) remain elusive. Therefore, we performed a systematic review to explore the potential etiologies for the development of CKDu globally. (2) Methods: A systematic literature review was conducted using databases CINAHL, Cochrane Library, Embase, Google Scholar, MEDLINE, and PsycINFO on the specific causes and pathophysiology related to CKDu from inception until April 2021. Study selection, data extraction of included articles, and quality appraisal were assessed. The narrative approach was used to summarize and comprehend the findings. (3) Results: Our study included 25 studies, considering 38,351 participants. Twelve studies were case-control, ten were cross-sectional, and three were cohort designs. All articles were from low-and middle-income countries (LMICs). The findings suggest 12 factors are associated with CKDu. Most studies (n = 8) identified farming and water sources as the factors related to CKDu, with heavy metal toxicity coming in second (n = 7). (4) Conclusion: The systematic review reported various factors associated with CKDu, from which most studies reported farming, water sources, and heavy metal poisoning. Considering the findings, the study recommends future strategies and public health initiatives to prevent the epidemiological/environmental factors contributing to CKDu.

Climate change and nephrology

Climate change should be of special concern for the nephrologist, as the kidney has a critical role in protecting the host from dehydration, but it is also a favorite target of heat stress and dehydration. Here we discuss how rising temperatures and extreme heat events may affect the kidney. The most severe presentation of heat stress is heat stroke, which can result in severe electrolyte disturbance and both acute and chronic kidney disease (CKD). However, lesser levels of heat stress also have multiple effects, including exacerbating kidney disease and precipitating cardiovascular events in subjects with established kidney disease. Heat stress can also increase the risk for kidney stones, cause multiple electrolyte abnormalities and induce both acute and chronic kidney disease. Recently there have been multiple epidemics of CKD of uncertain etiology in various regions of the world, including Mesoamerica, Sri Lanka, India and Thailand. There is increasing evidence that climate change and heat stress may play a contributory role in these conditions, although other causes, including toxins, could also be involved. As climate change worsens, the nephrologist should prepare for an increase in diseases associated with heat stress and dehydration.

A review of molecular mechanisms linked to potential renal injury agents in tropical rural farming communities

The chronic kidney disease of unknown etiology (CKDu) is a global health concern primarily impacting tropical farming communities. Although the precise etiology is debated, CKDu is associated with environmental exposures including heat stress and chemical contaminants such as fluoride, heavy metals, and herbicide glyphosate. However, a comprehensive synthesis is lacking on molecular networks underpinning renal damage induced by these factors. Addressing this gap, here we present key molecular events associated with heat and chemical exposures. We identified that caspase activation and lipid peroxidation are common endpoints of glyphosate exposure, while vasopressin and polyol pathways are associated with heat stress and dehydration. Heavy metal exposure is shown to induce lipid peroxidation and endoplasmic reticulum stress from ROS activated MAPK, NFĸB, and caspase. Collectively, we identify that environmental exposure induced increased cellular oxidative stress as a common mechanism mediating renal cell inflammation, apoptosis, and necrosis, likely contributing to CKDu initiation and progression.

Chronic kidney disease of unknown etiology in India: a comparative study with Mesoamerican and Sri Lankan nephropathy

Chronic kidney disease of unknown etiology [CKDu] is a condition characterized by decline in kidney function and is not associated with diabetic nephropathy or hypertensive nephropathy. In this review, we have done a detailed literature analysis on CKDu in India, and then had a comparison with that of Mesoamerica and Sri Lanka. In India, CKDu became the second most common type of CKD after diabetic nephropathy. Silica was seen in the groundwater of both India and Sri Lanka, whereas in Mesoamerica silica exposure through particulate matter was seen among CKDu communities. DDE is a common agrochemical seen in both India and Sri Lanka. The risk factors vary from region to region and it is important to categorize CKDu population based on the risk factors to avoid misinterpretation of the condition as non-CKDu category and to evade further complications. More studies have to be conducted to reveal the detailed pathophysiological mechanisms and its relation with irrational exploitation of environmental resources.

Multi-pronged research on endemic chronic kidney disease of unknown etiology in Sri Lanka: a systematic review

Increasing prevalence of endemic chronic kidney disease of unknown etiology (CKDu) in Sri Lanka is a major health problem since the 1990s. Despite numerous studies on CKDu, research groups have been unable to develop a comprehensive approach to mitigate the disorder, and thereby to identify research gaps. We conducted a systematic literature review of 119 publications on CKDu in Sri Lanka from Pubmed, Google Scholar, and Scopus, published until end September 2020. A higher CKDu prevalence in the working population of the North Central Province was reported with recent studies indicating patients from non-endemic regions as well. A majority were etiological studies that recorded conflicting and inconclusive evidence on CKDu etiology. Studies on clinico-pathological, diagnostic, biochemical, and molecular biological aspects of CKDu, studies analyzing CKDu symptom burden, anthropological, and behavioral impacts of CKDu, were reviewed as well. A dearth of research exists on nutritional, demographical, immunological, and microbial aspects of CKDu. The overview of the reviewed literature indicated the absence of a comprehensive plan of action to mitigate this situation. Hence, we propose the "One Health" approach with a systems dynamics model as a potential way forward to alleviate the CKDu epidemic in Sri Lanka. This enables the representation of multiple causative agents (and interactions thereof) among environmental, animal, and human systems, in concert with the "exposome" that provides the totality of exposure the individual has undergone since birth.

Risk factors for endemic chronic kidney disease of unknown etiology in Sri Lanka: Retrospect of water security in the dry zone

The prevalence of chronic kidney disease of unknown etiology (CKDu) is receiving considerable attention due to the serious threat to human health throughout the world. However, the roles of geo-socio-environmental factors in the prevalence of the CKDu endemic areas are still unknown. Sri Lanka is one of the countries most seriously affected by CKDu, where 10 out of 25 districts have been identified as the areas with the high prevalence of CKDu (10-20%). This review summarizes the geographical distribution of CKDu and its probable geochemical, behavioral, sociological, and environmental risk factors based on research related to hydrogeochemical influences on CKDu in Sri Lanka. More than 98% of CKDu patients have consumed groundwater as their primary water source in daily life, indicating the interactions of geogenic contaminants (such as F^-, total dissolved solids, Hofmeister ions) in groundwater is responsible for the disease. Apart from the hydrogeochemical factors, mycotoxins, cyanotoxins, use of some herbal medicines, dehydration, and exposure to agrochemicals were alleged as risk factors. Sociological factors, including poverty, living habits and anthropogenic activities, may also provoke the emergence of CKDu. Therefore, the interaction of geo-socio environmental risk factors should be sociologically and scientifically considered to prevent the prevalence of CKDu. Future in-depth studies are required to reveal the individual role of each of the postulated etiological factors, possibly using machine learning and advanced statistics.

Utility of Self-Reported Heat Stress Symptoms and NGAL Biomarker to Screen for Chronic Kidney Disease of Unknown Origin (CKDu) in Sri Lanka

Objective. We examined heat stress symptoms and urine markers of chronic kidney disease (CKDu) in Sri Lanka to assess differences between endemic vs. non-endemic regions and by occupation. Sample and Methods. We assessed a total of 475 villagers. In the endemic region, 293 were agricultural workers and 67 were not working primarily in agriculture. In the non-endemic region, 76 were agricultural workers. Of the residents, 218 were assessed for neutrophil gelatinase-associated lipocalin (NGAL), an early predictor of acute kidney injury, along with urine markers of chronic kidney disease. Results. The mean (sd) age of the sample was 45.2 (12.6), with males comprising 52.7%; 7.2% reported kidney disease (n = 34), and 5.7% reported diabetes (n = 27). The heat stress index (mean (sd)) was highest among agricultural workers in the endemic region (8.05 (5.9)), intermediate in non-agricultural workers in the endemic region (4.61 (4.5)), and lowest among agricultural workers in the non-endemic region (3.85 (3.3)); p < 0.0001. Correlations were higher between NGAL and serum microalbumin in the endemic agricultural worker sample than in the other two samples (Spearman’s r = 0.34 vs. 0.15 and 0.20). Conclusions. Both heat stress symptoms and NGAL values were higher among agricultural workers in endemic CKDu regions. Correlations between NGAL and microalbumin suggested a link between acute kidney injury and chronic kidney disease in the more-exposed sample.

Awareness of dehydration state and fluid intake practice among adults population in the Jazan Region of Saudi Arabia, 2019

Despite the hot climate and high humidity in the Jazan Region of Saudi Arabia, which increases risk for dehydration, no previous studies have assessed awareness of dehydration and fluid intake practice among adults in this region. Therefore, the aim of this cross-sectional study was to determine awareness of the dehydration state and fluid intake practices among 440 adults in the Jazan Region of Saudi Arabia. Out of the total, 51⋅8 % were male and 48⋅2 % were females. Good knowledge of dehydration definition and prevention and recommended minimum water intake was observed in 98, 95 and 75 % of the participants, respectively. Fifty-nine percent of the participants met the minimum daily requirement of 3 l or more per day. The age (95 % CI 1⋅003, 1⋅017, P value = 0⋅006), diabetes (95 % CI 1⋅028, 1⋅459, P value = 0⋅023) and prior hospitalisation due to dehydration (95 % CI 1⋅010, 1⋅378, P value = 0⋅037) were associated with higher water intake. Additional glasses of coffee (95 % CI 1⋅02, 1⋅115, P value = 0⋅004) and juice (95 % CI 1⋅039, 1⋅098, P value < 0⋅001) were associated with more water intake. The participants exhibited good knowledge of dehydration definition, symptoms and consequences. Intake of fluids such as 'juice and coffee' enhances more water intake. Although two-thirds of the participants met the recommended daily water intake, still one-third of them did not meet this level. Innovative approaches to enhance healthy drinking are warranted and may include partnering with patients to take an active role in hydration monitoring and increasing communication with the different healthcare providers.

Chronic Kidney Disease of Undetermined Etiology around the World

BACKGROUND

Epidemics of chronic kidney disease of uncertain etiology (CKDu) are occurring on the Pacific coast of Central America, in Sri Lankan and Indian agricultural communities, and in other hotspots around the world. CKDu primarily affects male agricultural workers, and traditional risk factors such as diabetes and hypertension are not involved in the pathogenesis. Although a causal factor has not yet been identified, culprits include repeated volume depletion-induced kidney injury, as well as exposure to agrichemicals, heavy metals and nephrotoxins contained in drugs, beverages, and traditional medications. Multiple risk factors may interact in a synergistic fashion thus resulting in chronic kidney damage. The absence of undefined protective factors may amplify the risk.

SUMMARY

This review focuses on the current understanding of CKDu by analyzing epidemiology, potential risk factors, and clinical and pathological features as well as geographical peculiarities of each disease. We also focus our attention on the etiology of these conditions in which multiple factors may synergistically contribute to the development and progression of the disease. The last part of the manuscript is dedicated to the research agenda and practical recommendations. Key Messages: Since renal replacement therapy is not extensively available in areas where CKDu is widespread, prevention by avoiding all known potential risk factors is crucial. Innovative healthcare solutions and social policies in endemic areas along with collaborative clinical research projects are needed to better identify factors involved in disease promotion and progression.

A comparative review: Chronic Kidney Disease of unknown etiology (CKDu) research conducted in Latin America versus Asia

INTRODUCTION

The incidence of chronic kidney disease of unknown or uncertain etiology (CKDu) is recognized as a global non-communicable health crisis. The goal of this work is to compare the types of research studies in Latin America and Asia, two regions with increasing CKDu incidence.

METHODS

A comparative literature review was conducted to evaluate the CKDu research design for peer-reviewed articles published from 2015 to 2019. Full texts were reviewed to identify study location, study type, study design, risk factors evaluated, and if applicable, sample type and number.

RESULTS

In Asia and Latin America, 82 and 65 articles were identified in total, respectively, with 55 field studies in Asia versus 34 in Latin America. In Asia, research was focused on drinking water (34), heavy metals (20), and agrochemical product usage (19) as potential risk factors. In Latin America, research focused mostly on heat stress/dehydration (36) and agrochemical product usage (18) as potential CKDu risk factors. Biological samples were collected more frequently than environmental samples, especially in Latin America.

DISCUSSION

Research to pinpoint the risk factors associated with CKDu to date is not standardized and typically limited in geographical scope. The emphasis of CKDu research varies by geographic region, with a greater priority placed on water quality and chemical exposure in Asia, versus dehydration and heat stress in Latin America. Using a harmonized approach to CKDu research would yield improved understanding of the risk factors associated with CKDu and how they compare across affected regions.

Progression of potential etiologies of the chronic kidney disease of unknown etiology in Sri Lanka

Chronic kidney disease of unknown etiology (CKDu) is a major health issue in agricultural areas in Sri Lanka. Despite many attempts to identifying causative factors of CKDu, the real cause/s remain/s elusive to date. Understanding the progression of potential etiologies may provide valuable insight into this quest. Literature relevant to CKDu addresses several etiologies, including quality of drinking water in the affected areas including hardness, fluoride, ionicity, agrochemical and heavy metal contaminations, consumption of contaminated food, and the genetic makeup of vulnerable populations. Progression of the etiologies revealed persistent interest in heavy metals of multiple origins: waterborne, foodborne, or soilborne. Secondary factors, such as water hardness, fluoride, and ionicity appear to act synergistically, aggravating the role of heavy metals on the onset, and the progression of CKDu. Demographical factors, such as male sex, over 50 years of age, agriculture-related occupation, and the consumption of contaminated water and food are intricately related with the disease progression while other minor risk factors such as smoking, alcohol consumption, etc. exasperate the disease condition. Since, none of these etiologies are examined adequately, conducting laboratory exposure studies under in-vivo and in-vitro settings to understand their role in CKDu is crucial.

Purposeful Review to Identify Risk Factors, Epidemiology, Clinical Features, Treatment and Prevention of Chronic Kidney Disease of Unknown Etiology

The global burden of chronic kidney disease (CKD) has risen, and chronic kidney disease of unknown etiology (CKDu) contributes considerably to the national burden of CKD. It is characterized by irreversible, slowly advancing disease, and symptoms often appear in the late stages of the disease. It is a serious, novel cause of kidney failure and leads to premature deaths. Many hypotheses have emerged; however, the etiology of CKDu continues to be elusive and debatable and it is claimed that the etiology is multifactorial, encompassing environmental, genetic, occupational, and social factors. The dominant histopathological feature is chronic tubulointerstitial nephritis. It predominantly affects individuals with low socio-economic status, of working age, largely without chronic comorbidities, who perform strenuous labor in extreme conditions in various tropical areas of the world. It is often fatal due to fast progression and limited access to dialysis or transplant options in the involved geographic areas. Early recognition and appropriate interventions at the earliest possible stage are imperative for decreasing its associated morbidity and mortality. In this review, I tried to summarize available evidence on the risk factors, epidemiology, clinical features, treatment, and prevention of CKDu. The literature search for this review was conducted comprehensively by using different electronic databases and by using appropriate search terms.

Using water quality and isotope studies to inform research in chronic kidney disease of unknown aetiology endemic areas in Sri Lanka

Chronic Kidney Disease of unknown aetiology (CKDu) is a major public health concern in dry climatic, agricultural regions of Sri Lanka. The chemistry of groundwater (the main source of drinking water) in the area has been studied extensively, in relation to the occurrence of CKDu. This paper investigates water quality studies published in CKDu affected areas of Sri Lanka and also presents a new data set of 27 hydrochemical and isotopic samples collected from groundwater wells in selected CKDu endemic areas in Sri Lanka. The study outcomes do not provide evidence of pollutants such as heavy metals in groundwater. However, the study identifies elevated concentrations of silica which requires further investigation. Two groups of groundwater have been identified based on the isotopic results suggesting different sources or origins. The available water quality data, including the data from this study, is not sufficient to answer questions on whether the chemistry of groundwater is related to the CKDu occurrence. However, this study identifies the importance of detailed investigation into degradation products of agrochemicals, the organic matter content and the influence of elevate silica concentration in groundwater. The study also provides research directions in the form of isotopic tracers and the frequency of sampling that is needed to capture potential pollutants in future groundwater quality studies in CKDu endemic areas in Sri Lanka.

Association of Hantavirus Infections and Leptospirosis With the Occurrence of Chronic Kidney Disease of Uncertain Etiology in the North Central Province of Sri Lanka: A Prospective Study With Patients and Healthy Persons

Chronic Kidney disease of uncertain etiology (CKDu) has become a significant disease burden, affecting farming community of Sri Lanka and the exact etiology, which could be multifactorial, is not hitherto established. This study is aimed to determine the association of past hantavirus infection and leptospirosis with the occurrence of CKDu. A cohort (n = 179) of known CKDu patients living in high-CKDu prevalent areas of Anuradhapura district of Sri Lanka was compared with a group of 49 healthy, sex-matched younger blood relatives of CKDu patients (control-1) and another 48 healthy, age, and sex-matched individuals living in low-CKDu prevalent area (control-2) of the same district where same life style and climate conditions prevail. Fifty out of 179 (27.9%) CKDu patients, 16/49 (32.7%) of control-1 and 7/48 (14.6%) of control-2 were found positive for IgG antibodies to Puumala, Hantaan or both strains of hantaviruses. Hantaan strain specificity was found to be predominant in all study groups. Hantavirus IgG sero-prevalence of healthy individuals living in low-CKDu prevalent area was significantly lower compared to CKDu patients and healthy younger blood relatives living in high-CKDu prevalent areas (p = 0.03). Past hantavirus infection possesses a significant risk for the occurrence of CKDu (OR = 4.5; 95% CI-3.1-5.4, p = 0.02). In contrast, IgG seroprevalence to hantaviruses was not significantly different in CKDu patients and healthy younger blood relatives living in high-CKDu prevalent areas indicating past hantavirus infection has no association with the occurrence of CKDu or possibly, younger relatives may develop CKDu in subsequent years. Seroprevalence to leptospirosis showed no significant difference between CKDu patients and healthy controls.

Chronic Interstitial Nephritis in Agricultural Communities (CINAC) in Sri Lanka

A significant increase in cases of chronic kidney disease has been observed in the dry zone of Sri Lanka. This unusual chronic kidney disease was first reported in the early 1990s among middle-aged paddy farmers. Considering epidemiologic and histopathologic findings, the disease recently was named chronic interstitial nephritis in agricultural communities (CINAC). Twenty-five years after the first report, CINAC is the most significant public health issue in the paddy farming areas with more than 70,000 estimated patients and many deaths. Histopathologically, this disease is a tubular interstitial nephritis associated with glomerular sclerosis and mild vascular changes. Morphologic and biochemical characteristics of CINAC in Sri Lanka share many similarities with Mesoamerican nephropathy. Certain natural and man-made toxins, heat stress with repeated volume and salt depletion, infections such as hantavirus and leptospirosis, and a genetic origin have been proposed and investigated as possible etiologies, and an association between CINAC and herbicides is widely discussed. Several preventive measures already have been implemented by health authorities in Sri Lanka to minimize nephrotoxin exposure and well hydrate the inhabitants in the disease-endemic region. The impact of these interventions will be watched with anticipation.

Genetic and Developmental Factors in Chronic Kidney Disease Hotspots

Chronic kidney disease increasingly is being recognized as an important global public health problem. Interindividual susceptibility to kidney disease is high and likely is dependent on risk modulation through genetics, fetal and early childhood development, environmental circumstances, and comorbidities. Traditionally, the chronic kidney disease burden has been ascribed largely to hypertension and diabetes. Increasingly, evidence is accumulating that nontraditional risk factors may predominate in some regions and populations, contributing to epidemics of kidney disease. Such nontraditional risk factors include environmental exposures, traditional medicines, fetal and maternal factors, infections, kidney stones, and acute kidney injury. Genetic factors may predispose patients to chronic kidney disease in some populations. Chronic kidney disease of unknown origin has its epicenters in Central America and South Asia. Such clustering of CKD may represent either genetic or environmentally driven kidney disease, or combinations of both. Developmental conditions impacting kidney development often are related to poverty and structural factors that persist throughout life. In this article, we explore the possibilities that genetic and developmental factors may be important contributors to the epidemics in these regions and suggest that optimization of factors impacting kidney development hold promise to reduce the risk of kidney disease in future generations.

Relevance of heat stress and dehydration to chronic kidney disease (CKDu) in Sri Lanka

Chronic kidney disease in the absence of hypertension and diabetes is a growing problem among agricultural laborers in tropical and subtropical regions. It is unclear if heat stress and dehydration are risk factors for this form of chronic kidney disease (CKDu). To investigate this relationship, agricultural workers in four villages (n = 261) in North Central Province, Sri Lanka completed the US National Institute for Occupational Safety and Health (NIOSH) health hazard evaluation of heat stress, translated into Sinhalese (July 2017). We constructed a heat stress/dehydration index based on the frequency of 16 symptoms (range 0-32; reliability, 0.84). Workers provided a urine sample for dipstick assessment of urine albumin-creatinine ratio (ACR) and refractometer analysis of urine concentration. Of 261 respondents, 41 participants reported diabetes or chronic kidney disease. They scored higher on the heat stress-dehydration index (10.78 vs. 8.03, p < .01) and were more likely to have ACR > 30 (85.4% vs. 69.4%, p < .05). Among 216 non-pregnant agricultural workers without diabetes or kidney disease (mean age, 46.6; 37% male), villagers in the high-CKDu prevalence area were more likely to show signs of dehydration (for example, greater urine concentration, 1.015 vs. 1.012, p < .05, among males); however, the heat stress-dehydration index overall was not associated with ACR or urine concentration. Because an elevated ACR (proteinuria) is not a reliable marker of early CKDu, additional studies are needed to assess the association between heat stress-dehydration symptoms and risk of CKDu.

A Review of Chronic Kidney Disease of Unknown Etiology in Sri Lanka, 2001-2015

An increase in the prevalence of chronic kidney disease of unknown etiology (CKDu) was observed in several countries of the world since the early 2000s. We reviewed the literature to summarize the existing knowledge regarding epidemiology, clinical features, and risk factors for CKDu in Sri Lanka. We reviewed published literature from PubMed and unpublished literature from literature repository of CKDu published by the World Health Organization. We identified 36 articles based on various inclusion/exclusion criteria and reviewed the full text of all selected articles. The prevalence of CKDu was approximately 5% in endemic areas based on the surveillance data. CKDu accounted for 70% of CKD cases in endemic areas. Clustering of cases was observed in select divisions and districts in the dry region of the country. Low body mass index, normal blood pressure, scanty proteinuria, and tubulointerstitial pathology were characteristics of early stages of a disease. Genetic susceptibility, farmer as occupation, heavy metals (cadmium and arsenic), and drinking well water were identified as risk factors. Data were limited on the association with agrochemical use and heat stress/dehydration. Community- and facility-based surveillance needs to be strengthened to document the burden of disease and trends over time.

Risk factors for chronic kidney disease of non-traditional causes: a systematic review

OBJECTIVES

To evaluate the potential associations between chronic kidney disease of uncertain or non-traditional etiology (CKDnT) and agrochemicals, heat stress, heavy metals, and other factors identified in the literature in any region of the world and at any time.

METHODS

This was a systematic review of the most frequent exposures suspected to be possible causes of CKDnT. A search was conducted of PubMed, LILACS, World Wide Science electronic databases, among other sources. Only medium- and high-quality studies were included. The synthesis of evidence included a narrative synthesis, meta-analysis, and meta-regression.

RESULTS

Four systematic reviews and 61 primary studies were included. Results of the meta-analysis suggest that exposure to agrochemicals and working in agriculture increase the risk of CKDnT, but this only reached significance for working in agriculture. When cross-sectional studies were excluded, agrochemical exposure became significant. However, there is substantial heterogeneity in the effect sizes.

CONCLUSIONS

Based on the existing evidence and the precautionary principle, it is important to implement preventive measures to mitigate the damage caused by CKDnT to both agricultural workers and their communities (i.e., improvement of working conditions, cautious management of agrochemicals, etc.). More high-quality research is needed to measure impact and to build the evidence base.

Risk Factors for Mortality in Children Admitted for Suspected Malaria to a Pediatric Emergency Ward in a Low-Resource Setting: A Case-Control Study

OBJECTIVES

To identify the risk factors for mortality after admission for suspected malaria in a pediatric emergency ward in Sierra Leone.

DESIGN

Retrospective case-control.

SETTING

Pujehun Hospital Pediatric Ward in Pujehun, Sierra Leone.

PATIENTS

All cases were pediatric deaths after admission for suspected malaria at the Pujehun Hospital Pediatric Ward between January 1, 2015, and May 31, 2016. The case-control ratio was 1:1. The controls were infants admitted at Pujehun Hospital Pediatric Ward for malaria and discharged alive during the same period. Controls were selected as the next noncase infant admitted for malaria and discharged alive, as recorded in local medical records.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Children characteristics, vital variables on hospital access, comorbidity status at admission, antibiotic and antimalarial therapy at admission; presence of hematemesis, respiratory arrest or bradypnea, abrupt worsening, and emergency interventions during hospital stay; final diagnosis before discharge or death. In total, 320 subjects (160 cases and 160 controls) were included in the study. Multivariable analysis identified being referred from peripheral health units (odds ratio, 4.00; 95% CI, 1.98-8.43), cerebral malaria (odds ratio, 6.28; 95% CI, 2.19-21.47), malnutrition (odds ratio, 3.14; 95% CI, 1.45-7.15), dehydration (odds ratio, 3.94; 95% CI, 1.50-11.35), being unresponsive or responsive to pain (odds ratio, 2.17; 95% CI, 1.15-4.13), and hepatosplenomegaly (odds ratio, 3.20; 95% CI, 1.74-6.03) as independent risk factors for mortality.

CONCLUSIONS

Risk factors for mortality in children with suspected malaria include cerebral malaria and severe clinical conditions at admission. Being referred from peripheral health units, as proxy of logistics issue, was also associated with increased risk of mortality. These findings suggest that appropriate interventions should focus on training and resources, including the increase of dedicated personnel and available equipment.

Global kidney health 2017 and beyond: a roadmap for closing gaps in care, research, and policy

The global nephrology community recognises the need for a cohesive plan to address the problem of chronic kidney disease (CKD). In July, 2016, the International Society of Nephrology hosted a CKD summit of more than 85 people with diverse expertise and professional backgrounds from around the globe. The purpose was to identify and prioritise key activities for the next 5-10 years in the domains of clinical care, research, and advocacy and to create an action plan and performance framework based on ten themes: strengthen CKD surveillance; tackle major risk factors for CKD; reduce acute kidney injury-a special risk factor for CKD; enhance understanding of the genetic causes of CKD; establish better diagnostic methods in CKD; improve understanding of the natural course of CKD; assess and implement established treatment options in patients with CKD; improve management of symptoms and complications of CKD; develop novel therapeutic interventions to slow CKD progression and reduce CKD complications; and increase the quantity and quality of clinical trials in CKD. Each group produced a prioritised list of goals, activities, and a set of key deliverable objectives for each of the themes. The intended users of this action plan are clinicians, patients, scientists, industry partners, governments, and advocacy organisations. Implementation of this integrated comprehensive plan will benefit people who are at risk for or affected by CKD worldwide.

Reducing major risk factors for chronic kidney disease

Chronic kidney disease (CKD) is a global public health concern and a key determinant of poor health outcomes. While the burden of CKD is reasonably well defined in developed countries, increasing evidence indicates that the CKD burden may be even greater in developing countries. Diabetes, hypertension, and obesity are major contributors to the global burden of the disease and are important traditional CKD risk factors; however, nontraditional CKD risk factors such as nephrotoxin exposure, kidney stones, fetal and maternal factors, infections, environmental factors, and acute kidney injury are also increasingly being recognized as major threats to global kidney health. A broad approach to CKD prevention begins with the identification of CKD risk factors in the population, followed by the development of appropriate mitigation strategies. Effective prevention policies rely on an accurate understanding of the incidence and prevalence of CKD in a given setting, as well as the distribution and burden of risk factors. Populations or individuals at CKD risk must be screened and treated early to prevent the onset of and delay the progression of the kidney disease. Systematically collected data should be analyzed at country, province, and district levels to identify regional disparities and CKD hotspots and develop targeted prevention strategies. Race-ethnicity, genetics, sex, socioeconomic status, and geography are likely modifiers of CKD risk. A comprehensive, informed approach to prevention that takes into account all of these factors is therefore required to successfully tackle the global CKD epidemic.

Kidney involvement in malaria: an update

Malaria is an infectious disease of great importance for Public Health, as it is the most prevalent endemic disease in the world, affecting millions of people living in tropical areas of the globe. Kidney involvement is relatively frequent in infections by P. falciparum and P. malariae, but has also been described in the infection by P. vivax. Kidney complications in malaria mainly occur due to hemodynamic dysfunction and immune response. Liver complications leading to hepatomegaly, jaundice and hepatic dysfunction can also contribute to the occurrence of acute kidney injury. Histologic studies in malaria also evidence glomerulonephritis, acute tubular necrosis and acute interstitial nephritis. It is also possible to find chronic kidney disease associated with malaria, mainly in those patients suffering from repeated episodes of infection. Plasmodium antigens have already been detected in the glomeruli, suggesting a direct effect of the parasite in the kidney, which can trigger an inflammatory process leading to different types of glomerulonephritis. Clinical manifestations of kidney involvement in malaria include proteinuria, microalbuminuria and urinary casts, reported in 20 to 50% of cases. Nephrotic syndrome has also been described in the infection by P. falciparum, but it is rare. This paper highlights the main aspects of kidney involvement in malaria and important findings of the most recent research addressing this issue.

Con: Mesoamerican nephropathy: is the problem dehydration or rehydration?

In recent years, an increasing number of inhabitants of Central America have developed a form of chronic kidney disease, now named Mesoamerican nephropathy. This disease is characterized by minimal proteinuria, hyperuricemia, hypokalemia and reduced glomerular filtration rate. Histologically the kidneys manifest tubulointerstitial nephritis. The cause(s) of this disease remain unknown. Some have proposed that dehydration, in combination with hyperuricemia, may be primarily responsible for Mesoamerican nephropathy. In this article, I propose the hypothesis that the disease may be largely due to rehydration with large amounts of contaminated water, whereas dehydration would play only a contributing role.

Causal mechanism and component causes in Mesoamerican-Sri Lankan nephropathy: the moderator's view

Inspired by Conan Doyle's novels, the pro contender of this Polar View undertakes an elegant exercise in territory common to epidemiology and police investigation and concludes that cyclic episodes of dehydration in individuals exposed to heavy work in very hot climates is the cause of Mesoamerican and Sri Lankan nephropathy. The contender in the opposite camp accepts the idea that dehydration may play a key role in this condition but highlights a different explanation, that it is contaminated water used for rehydration that is the eventual cause of the disease.Causal mechanisms result from the combination of many components, i.e. conditions or events that are needed for the occurrence of the disease. If we adopt a global, extended approach to the problem, it is unlikely that cyclic dehydration is a key component in all cases. While credible in most cases in Central America, the cyclic dehydration hypothesis fails to explain most cases in Sri Lanka, where agrochemicals have been implicated as the most likely cause of this disease. The experience with Balkan nephropathy is an enduring lesson that full clarification of the causal mechanisms behind endemic nephropathies can be a decades-long process. Therefore, action to control Mesoamerican and Sri Lankan nephropathy should not be deferred. Deployable interventions include the provision of uncontaminated water sources, prevention of dehydration at work sites and the application of safety procedures for agrochemicals. The joint application of these interventions will most likely benefit the populations plagued by this endemic disease.

Pro: Heat stress as a potential etiology of Mesoamerican and Sri Lankan nephropathy: a late night consult with Sherlock Holmes

Epidemics of chronic kidney disease are now recognized in Central America, Mexico, India and Sri Lanka, and there is also some evidence that similar epidemics may be occurring in the USA, Thailand and elsewhere. A common denominator for each location is manually working outside in extremely hot environments. Here we review the evidence that the primary etiology may be heat stress related to repeated subclinical or clinical acute kidney injury that eventually manifests as chronic kidney disease. In some aspects, the disease may manifest as subclinical heat stroke, subclinical rhabdomyolysis or a subclinical tumor lysis syndrome. While toxins could be involved, it would be difficult to attribute this as a main mechanism, given the wide range of occupations and geographic regions manifesting this disease. While some of the epidemics may be due to better reporting, we believe the most important reasons are increasing heat extremes (heat waves) coupled with hydration with sugary or, less commonly, alcoholic beverages.

Endemic Nephropathy Around the World

There have been several global epidemics of chronic kidney disease of unknown etiology (CKDu). Some, such as Itai-Itai disease in Japan and Balkan endemic nephropathy, have been explained, whereas the etiology of others remains unclear. In countries such as Sri Lanka, El Salvador, Nicaragua, and India, CKDu is a major public health problem and causes significant morbidity and mortality. Despite their geographical separation, however, there are striking similarities between these endemic nephropathies. Young male agricultural workers who perform strenuous labor in extreme conditions are the worst affected. Patients remain asymptomatic until end-stage renal failure. Biomarkers of tubular injury are raised, and kidney biopsy shows chronic interstitial nephritis with associated tubular atrophy. In many of these places access to dialysis and transplantation is limited, leaving few treatment options. In this review we briefly describe the major historic endemic nephropathies. We then summarize the epidemiology, clinical features, histology and clinical course of CKDu in Mesoamerica, Sri Lanka, India, Egypt, and Tunisia. We draw comparisons between the proposed etiologies and supporting research. Recognition of the similarities may reinforce the international drive to establish causality and to effect prevention.

Upregulation of Oxidative Stress Related Genes in a Chronic Kidney Disease Attributed to Specific Geographical Locations of Sri Lanka

Objective. To infer the influence of internal and external oxidative stress in chronic kidney disease patients of unknown etiology (CKDu) in Sri Lanka, by analyzing expression of genes related directly or indirectly to oxidative stress: glutamate-cysteine ligase catalytic subunit (GCLC), glutathione S-transferase mu 1 (GSTM1), glucose-6-phosphate dehydrogenase (G6PD), fibroblast growth factor-23 (FGF23), and NLR family pyrin domain containing 3 (NLRP3). Methods. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was carried out for the selected populations: CKDu patients (n = 43), chronic kidney disease patients (CKD; n = 14), healthy individuals from a CKDu endemic area (GHI; n = 9), and nonendemic area (KHI; n = 16). Fold changes were quantified relative to KHI. Results. GCLC had greater than threefold upregulation in all three study groups, with a maximum of 7.27-fold upregulation in GHI (p = 0.000). GSTM1 was not expressed in 25.6% of CKDu and 42.9% of CKD patients, but CKDu patients expressing GSTM1 showed upregulation of 2.60-fold (p < 0.05). Upregulation of FGF23 and NLRP3 genes in CKD and CKDu was observed (p < 0.01), with greater fold changes in CKD. Conclusion. Results suggest higher influence of external sources of oxidative stress in CKDu, possibly owing to environmental conditions.

Climate Change and the Emergent Epidemic of CKD from Heat Stress in Rural Communities: The Case for Heat Stress Nephropathy

Climate change has led to significant rise of 0.8°C-0.9°C in global mean temperature over the last century and has been linked with significant increases in the frequency and severity of heat waves (extreme heat events). Climate change has also been increasingly connected to detrimental human health. One of the consequences of climate-related extreme heat exposure is dehydration and volume loss, leading to acute mortality from exacerbations of pre-existing chronic disease, as well as from outright heat exhaustion and heat stroke. Recent studies have also shown that recurrent heat exposure with physical exertion and inadequate hydration can lead to CKD that is distinct from that caused by diabetes, hypertension, or GN. Epidemics of CKD consistent with heat stress nephropathy are now occurring across the world. Here, we describe this disease, discuss the locations where it appears to be manifesting, link it with increasing temperatures, and discuss ongoing attempts to prevent the disease. Heat stress nephropathy may represent one of the first epidemics due to global warming. Government, industry, and health policy makers in the impacted regions should place greater emphasis on occupational and community interventions.

Metabolic and Kidney Diseases in the Setting of Climate Change, Water Shortage, and Survival Factors

Climate change (global warming) is leading to an increase in heat extremes and coupled with increasing water shortage, provides a perfect storm for a new era of environmental crises and potentially, new diseases. We use a comparative physiologic approach to show that one of the primary mechanisms by which animals protect themselves against water shortage is to increase fat mass as a means for providing metabolic water. Strong evidence suggests that certain hormones (vasopressin), foods (fructose), and metabolic products (uric acid) function as survival signals to help reduce water loss and store fat (which also provides a source of metabolic water). These mechanisms are intricately linked with each other and stimulated by dehydration and hyperosmolarity. Although these mechanisms were protective in the setting of low sugar and low salt intake in our past, today, the combination of diets high in fructose and salty foods, increasing temperatures, and decreasing available water places these survival signals in overdrive and may be accelerating the obesity and diabetes epidemics. The recent discovery of multiple epidemics of CKD occurring in agricultural workers in hot and humid environments may represent harbingers of the detrimental consequences of the combination of climate change and overactivation of survival pathways.