Exposure to Hantavirus is a Risk Factor Associated with Kidney Diseases in Sri Lanka: A Cross Sectional Study

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.

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.

Occupational Hantavirus Infections in Agricultural and Forestry Workers: A Systematic Review and Metanalysis

Hantaviruses are zoonotic pathogens that can cause serious human disorders, including hemorrhagic fever with renal syndrome and hantavirus cardiopulmonary syndrome. As the main risk factor for human infections is the interaction with rodents, occupational groups such as farmers and forestry workers are reportedly at high risk, but no summary evidence has been collected to date. Therefore, we searched two different databases (PubMed and EMBASE), focusing on studies reporting the prevalence of hantaviruses in farmers and forestry workers. Data were extracted using a standardized assessment form, and results of such analyses were systematically reported, summarized and compared. We identified a total of 42 articles, including a total of 28 estimates on farmers, and 22 on forestry workers, with a total workforce of 15,043 cases (821 positive cases, 5.5%). A pooled seroprevalence of 3.7% (95% confidence interval [95% CI] 2.2–6.2) was identified in farmers, compared to 3.8% (95% CI 2.6–5.7) in forestry workers. Compared to the reference population, an increased occurrence was reported for both occupational groups (odds ratio [OR] 1.875, 95% CI 1.438–2.445 and OR 2.892, 95% CI 2.079–4.023 for farmers and forestry workers, respectively). In summary, our analyses stress the actual occurrence of hantaviruses in selected occupational groups. Improved understanding of appropriate preventive measures, as well as further studies on hantavirus infection rates in reservoir host species (rodents, shrews, and bats) and virus transmission to humans, is needed to prevent future outbreaks.

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.

Prevalence and risk factors of Hantavirus infection in patients undergoing hemodialysis in Khartoum, Sudan, in 2019: a cross-sectional study

BACKGROUND

Hantaviruses are enveloped negative sense RNA viruses that cause hemorrhagic fever with renal syndrome. This study aimed to identify the prevalence of Hantavirus IgG antibodies and possible risk factors for Hantaviruses infections among end-stage renal disease (ESRD) patients attending the Dr Salma dialysis center in Sudan.

METHODOLOGY

This was a cross-sectional study in which 91 ESRD patients and 30 healthy plasma samples were screened for Hantavirus IgG antibodies using ELISA. A questionnaire containing sociodemographics, history of rat exposure and clinical data information was filled in by each ESRD patient.

RESULTS

In this study, 9 out of 91 ESRD patients (9.9%) tested positive for Hantaviruses antibodies (IgG) while none of the 30 healthy plasma samples showed seropositivity. There was no statistically significant association between age, gender, educational level and rat exposure and Hantavirus infection in ESRD patients (p>0.05).

CONCLUSION

This study is the first to be conducted in Sudan regarding Hantaviruses and ESRD. The prevalence of Hantavirus antibodies among ESRD patients is high compared with findings reported in the literature from studies conducted on the same group of patients. It points to an interesting question as to whether Hantaviruses have an association with ESRD but further studies are needed before drawing any conclusions.

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.

Serological methods for detection of infection with shrew-borne hantaviruses: Thottapalayam, Seewis, Altai, and Asama viruses

The infectivity of shrew-borne hantaviruses to humans is still unclear because of the lack of a serodiagnosis method for these viruses. In this study, we prepared recombinant nucleocapsid (rN) proteins of Seewis orthohantavirus, Altai orthohantavirus (ALTV), Thottapalayam thottimvirus (TPMV), and Asama orthohantavirus. Using monospecific rabbit sera, no antigenic cross-reactivity was observed. In a serosurvey of 104 samples from renal patients and 271 samples from heathy controls from Sri Lanka, one patient serum and two healthy control sera reacted with rN proteins of ALTV and TPMV, respectively. The novel assays should be applied to investigate potential infectivity of shrew-borne hantaviruses to humans.

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.

Understanding leptospirosis eco-epidemiology by environmental DNA metabarcoding of irrigation water from two agro-ecological regions of Sri Lanka

Background

Leptospirosis is one of the most significant zoonoses across the world not only because of its impact on human and animal health but also because of the economic and social impact on agrarian communities. Leptospirosis is endemic in Sri Lanka where paddy farming activities, the use of draught animals in agriculture, and peridomestic animals in urban and rural areas play important roles in maintaining the infection cycle of pathogenic Leptospira, especially concerning animals as a potential reservoir. In this study, an environmental DNA (eDNA) metabarcoding methodology was applied in two different agro-ecological regions of Sri Lanka to understand the eco-epidemiology of leptospirosis.

Methodology/Principal findings

Irrigation water samples were collected in Kandy District (wet zone mid-country region 2) and Girandurukotte, Badulla District (intermediate zone low-country region 2); and analysed for the presence of pathogenic Leptospira, associated microbiome and the potential reservoir animals. Briefly, we generated PCR products for high-throughput sequencing of multiple amplicons through next-generation sequencing. The analysis of eDNA showed different environmental microbiomes in both regions and a higher diversity of Leptospira species circulating in Kandy than in Girandurukotte. Moreover, the number of sequence reads of pathogenic Leptospira species associated with clinical cases such as L. interrogans was higher in Kandy than in Girandurukotte. Kandy also showed more animal species associated with pathogenic bacterial species than Girandurukotte. Finally, several pathogenic bacterial species including Arcobacter cryaerophilus, responsible for abortion in animals, was shown to be associated with pathogenic Leptospira.

Conclusions/Significance

Leptospirosis has been considered to be endemic in wet regions, consistently, leptospiral sequences were detected strongly in Kandy. The great Leptospira species diversity in Kandy observed in this study shows that the etiological agents of leptospirosis in Sri Lanka might be underestimated. Furthermore, our eDNA metabarcoding can be used to discriminate bacterial and animal species diversity in different regions and to explore environmental microbiomes to identify other associated bacterial pathogens in the environment.

Leptospirosis is a widespread bacterial zoonosis with increasing importance due to its vast range of reservoir hosts. Early symptoms are shared by other infectious diseases common in tropical and sub-tropical regions, where the real burden and risk factors need to be known. In Sri Lanka, leptospirosis is mostly an occupational disease associated with freshwater or animal exposure in agriculture communities. Thus, there is a need for understanding the epidemiology of leptospirosis in agrarian regions of the country for developing better prevention and intervention strategies. In this study, we applied an environmental DNA metabarcoding methodology to understand the environmental microbiome, potential reservoir animals and the Leptospira species circulating in two different agro-ecological regions of Sri Lanka: Kandy (wet region mid-country region 2) and Girandurukotte (intermediate region low-country region 2). It is known that pathogenic Leptospira are excreted through the urine of reservoir animals in the environment, where they can persist in humid conditions. Congruently, this study showed a higher detection of pathogenic Leptospira in the environment of Kandy where the environmental microbiome showed a higher diversity than Girandurukotte. Potential animal reservoirs were also detected in samples positive for pathogenic Leptospira, suggesting that environmental DNA metabarcoding can provide important information for management and intervention strategies to control leptospirosis.

[Hantavirus infection as a risk for chronic kidney disease of unknown etiology (CKDu) in Sri Lanka]

Chronic kidney disease of unknown etiology (CKDu) has emerged in endemic areas of Sri Lanka since the 1990s. The disease is a chronic but fatal disease. Until now, heavy metals and agrochemicals have been suspected as the cause of CKDu, but it has been still unknown. Recently, we have found a high seroprevalence to hantavirus in CKDu patients and reported that hantavirus infection is a risk of CKDu. Hantaviruses are rodent-borne zoonotic viruses. Here, I would like to introduce a story of the research from sero-epidemiology to the search for host animals.