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

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.

Environmental Change, Changing Biodiversity, and Infections-Lessons for Kidney Health Community

There is a direct and accelerating connection between ongoing environmental change, the unprecedented decline in biodiversity, and the increase in infectious disease epidemiology worldwide. Rising global temperatures are threatening the biodiversity that underpins the richness and diversity of flora and fauna species in our ecosystem. Anthropogenic activities such as burning fossil fuels, deforestation, rapid urbanization, and expanding population are the primary drivers of environmental change resulting in biodiversity collapse. Climate change is influencing the emergence, prevalence, and transmission of infectious diseases both directly and through its impact on biodiversity. The environment is gradually becoming more suitable for infectious diseases by affecting a variety of pathogens, hosts, and vectors and by favoring transmission rates in many parts of the world that were until recently free of these infections. The acute effects of these zoonotic, vector and waterborne diseases are well known; however, evidence is emerging about their role in the development of chronic kidney disease. The pathways linking environmental change and biodiversity loss to infections impacting kidney health are diverse and complex. Climate change and biodiversity loss disproportionately affect the vulnerable and limit their ability to access healthcare. The kidney health community needs to contribute to the issue of environmental change and biodiversity loss through multisectoral action alongside government, policymakers, advocates, businesses, and the general population. We describe various aspects of the environmental change effects on the transmission and emergence of infectious diseases particularly focusing on its potential impact on kidney health. We also discuss the adaptive and mitigation measures and the gaps in research and policy action.

Association of Single Nucleotide Polymorphisms in KCNA10 and SLC13A3 Genes with the Susceptibility to Chronic Kidney Disease of Unknown Etiology in Central Indian Patients

Global rise in the prevalence of endemic chronic kidney disease of unknown etiology (CKDu) possess major health issues. The prevalence of CKDu is also rising in the Indian population. Besides environmental factors, genetic factors play an important role in the predisposition to CKDu. In the present study, we have analyzed the association of single nucleotide polymorphisms (SNPs) in three genes with the susceptibility to CKDu. This was a case-control study with a total of 180 adult subjects (CKD = 60, CKDu = 60, Healthy = 60) from central India. We performed KASP genotyping assay to determine the allele frequency of SNP genotypes. We used the odds ratio (OR) to assess the association of individual SNPs, rs34970857 of KCNA10, rs6066043 of SLC13A3, and rs2910164 of miR-146a with CKDu and CKD susceptibility. In the case of rs34970857 of the KCNA10 gene, we noted a significantly increased OR for CKDu versus healthy control (Dominant model; CKDu versus control, CT + CC versus TT, OR = 3.96, p = 0.004). In the recessive and homozygous model, we observed significantly increased OR for rs6066043 of SLC13A3 gene, CKDu versus healthy control {(Recessive model; CKDu versus control, GG versus AA + GA, OR = 2.41, p = 0.03; homozygous model, GG versus AA, OR = 3.54, p = 0.04)}. CC genotype of rs34970857 of the KCNA10 gene and the GG genotype of the SLC13A3 gene are significantly associated with the susceptibility of CKDu.

Urinary MicroRNA Analysis Indicates an Epigenetic Regulation of Chronic Kidney Disease of Unknown Etiology in Sri Lanka

BACKGROUND

Chronic kidney disease of unknown etiology (CKDu) is reported among male paddy farmers in the dry zone of Sri Lanka. The exact cause of this disease remains undetermined. Genetic susceptibility is identified as a major risk factor for CKDu Objectives: In this study, small urinary RNAs were characterized in CKDu patients, healthy endemic and non-endemic controls. Differently expressed urinary miRNAs and their associated pathways were identified in the study population.

METHODS

Healthy and diseased male volunteers (n = 9) were recruited from Girandurukotte (endemic) and Mawanella (non-endemic) districts. Urinary small RNAs were purified and sequenced using Illumina MiSeqTM. The sequence trace files were assembled and analyzed. Differentially ex-pressed miRNAs among these three groups were identified and pathway analysis was conducted.

RESULTS

The urine samples contained 130,623 sequence reads identified as non-coding RNAs, PIWI-interacting RNAs (piRNA), and miRNAs. Approximately four percent of the total small RNA reads represented miRNA, and 29% represented piRNA. A total of 409 miRNA species were ex-pressed in urine. Interestingly, both diseased and endemic controls population showed significantly low expression of miRNA and piRNA. Regardless of the health status, the endemic population ex-pressed significantly low levels of miR-10a, miR-21, miR-148a, and miR-30a which have been linked with several environmental toxins Conclusion: Significant downregulation of miRNA and piRNA expression in both diseased and healthy endemic samples indicates an epigenetic regulation of CKDu involving genetic and environmental interaction. Further studies of specific miRNA species are required to develop a miRNA panel to identify individuals susceptible to CKDu.

Evidence of orthohantavirus and leptospira infections in small mammals in an endemic area of Gampaha district in Sri Lanka

BACKGROUND

Orthohantaviruses and leptospira are emerging zoonotic pathogens of high public health significance. The epidemiology of orthohantavirus infections and leptospirosis is similar and presents related clinical pictures in humans. However, a paucity of data on actual reservoir hosts for orthohantaviruses and leptospira exists. Therefore, this study aimed at determining the occurrence of orthohantaviruses and leptospira in small mammals captured in an endemic region of Sri Lanka.

METHODS

Rodents and shrews were morphologically and/or genetically identified using morphological keys and DNA barcoding techniques targeting the cytochrome oxidase b subunit gene (Cytb). Lung tissues and sera were subsequently analyzed for the presence of orthohantavirus RNA using qRT-PCR. Sera of rats were tested for IgG antibodies against orthohantaviruses and leptospira.

RESULTS

Forty-three (43) small mammals representing: Rattus (R.) rattus (black rat) or R. tanezumi (Asian rat), Suncus murinus (Asian house shrew), R. norvegicus (brown rat) and Mus musculus (house mouse) were investigated. No orthohantavirus RNA was detected from the lung tissue or serum samples of these animals. Elevated levels of IgG antibodies against Puumala orthohantavirus (PUUV) and/or Seoul orthohantavirus (SEOV) antigens were detected in sera of 28 (72%) out of the 39 rats analysed. Interestingly, 36 (92%) of the 39 rats also showed presence of anti leptospira-IgG antibodies in their serum, representing dual infection or dual exposure in 26/39 (66.7%) of examined rats.

CONCLUSIONS

This project targets important public health questions concerning the occupational risk of orthohantavirus infections and/or leptospirosis in an endemic region of Sri Lanka. Most rats (72%) in our study displayed antibodies reacting to orthohantavirus NP antigens, related to PUUV and/or SEOV. No correlation between the orthohantavirus and leptospira IgG antibody levels were noticed. Finally, a combination of both morphological and DNA barcoding approaches revealed that several species of rats may play a role in the maintenance and transmission of orthohantavirus and leptospira in Sri Lanka.

Hantavirus infection as a risk factor for chronic kidney disease of unknown aetiology (CKDu) and its prevalence in endemic areas of Sri Lanka since 2010 according to a retrospective serological analysis

Background. Chronic kidney disease of unknown aetiology (CKDu) is a major public health problem in Sri Lanka, especially among agrarian communities. Although the cause of CKDu is still unknown, hantavirus infection has been proposed as a risk factor.Methods. This study was performed using serological samples collected from two CKDu-endemic areas, Anuradhapura (2010) and Badulla districts (2010 and 2016), and a non-endemic area, Matale (2016) district. The presence of anti-Thailand orthohantavirus IgG antibodies was investigated in serum samples. Hantavirus seroprevalence and demographic data were epidemiologically analysed.Results. Seroprevalence was higher in CKDu patients (40.6-60.0 %) and healthy individuals in CKDu-endemic areas (17.6-25.5 %) than in healthy individuals in non-endemic areas (3.0 %). Statistically significant odds ratios (ORs) for hantavirus infection in CKDu patients were detected in CKDu-endemic areas [ORs: 3.2 and 3.1; 95 % confidence interval (CI): 1.8-5.5 and 1.8-5.2 in Anuradhapura and Badulla districts in 2010; and OR: 4.4, 95 % CI: 2.3-8.5 in 2016 in Badulla district). Furthermore, the OR for hantavirus infection in Badulla district has increased in the last decade from 3.1 (95 % CI: 1.8-5.3) to 4.4 (95 % CI: 2.3-8.5).Conclusion. Hantavirus infection has been prevalent in two distant CKDu-endemic areas since 2010. The observed significant association of hantavirus seropositivity with CKDu indicates a possible role of hantavirus infection in CKDu pathogenesis.

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.

Identification of Novel Rodent-Borne Orthohantaviruses in an Endemic Area of Chronic Kidney Disease of Unknown Etiology (CKDu) in Sri Lanka

We reported the genetic evidence of circulating hantaviruses from small mammals captured in a chronic kidney disease of unknown etiology (CKDu) hotspot area of Sri Lanka. The high seroprevalence of anti-hantavirus antibodies against Thailand orthohantavirus (THAIV) has been reported among CKDu patients and rodents in Sri Lankan CKDu hotspots. We captured 116 small mammals from CKDu endemic regions in the Polonnaruwa District of Sri Lanka. Seven animals (five out of 11 Mus booduga and two out of 99 Rattus rattus) were PCR-positive for the hantavirus. A rat-borne sequence was grouped with a THAIV-like Anjozorobe virus. In contrast, Mus-borne sequences belonged to the THAIV lineage, suggesting a novel orthohantavirus species according to the phylogenetic analyses and whole-genome comparisons. Our genetic evidence indicates the presence of two THAIV-related viruses circulating in this CKDu endemic area, suggesting a basis for further investigations to identify the infectious virus in patients with CKDu and the CKDu induction mechanism of these viruses.