Surveillance of hepatitis E virus in sewage and drinking water in a resettlement colony of Delhi: what has been the experience?

Genotype 4 Hepatitis E virus replicates in the placenta, causes severe histopathological damage, and vertically transmits to fetuses

BACKGROUND

Hepatitis E virus (HEV) infection in pregnant women causes adverse pregnancy outcomes, including maternal death, premature delivery, stillbirth, and fetal infection. However, the pathogenesis of maternal and fetal HEV infection is unclear.

METHODS

Placenta and placental appendixes were collected from HEV-4 infected pregnant women to explore the vertical transmission of HEV from mothers to fetuses.

RESULTS

HEV-4 replicated in the placenta, placental membrane, and umbilical cord and was vertically transmitted from mothers to fetuses. HEV-4 placental infection resulted in serious histopathological damage, such as fibrosis and calcification, and severe inflammatory responses. Adverse maternal outcomes were observed in 38.5% of HEV-4 infected pregnant women. The distinct cytokine/chemokine expression patterns of HEV-infected pregnant women and nonpregnant women may contribute to the adverse pregnancy outcomes. Furthermore, the impaired maternal and fetal innate immune responses against HEV-4 facilitated viral replication during pregnancy.

CONCLUSION

HEV-4 replicates in the placenta and is vertically transmitted from mothers to fetuses, causing severe histopathological damage.

Clustered Cases of Waterborne Hepatitis E Virus Infection, France

The identification of seven cases of hepatitis E virus infection in a French rural hamlet in April 2015 led to investigations confirming the clustering and identifying the source of the infection. Laboratories and general practitioners in the area actively searched for other cases based on RT-PCR and serological tests. The environment, including water sources, was also checked for HEV RNA. Phylogenetic analyses were performed to compare HEV sequences. No other cases were found. Six of the seven patients lived in the same hamlet, and the seventh used to visit his family who lived there. All HEV strains were very similar and belonged to the HEV3f subgenotype, confirming the clustering of these cases. All the patients drank water from the public network. A break in the water supply to the hamlet was identified at the time the infection probably occurred; HEV RNA was also detected in a private water source that was connected to the public water network. The water flowing from the taps was quite turbid during the break. The private water supply containing HEV RNA was the likely source of the contamination. Private water supplies not disconnected from the public network are still frequent in rural areas, where they may contribute to public water pollution.

Hepatitis E Virus in Water Environments: A Systematic Review and Meta-analysis

Hepatitis E virus (HEV) is responsible for acute hepatitis in humans, through foodborne, zoonotic, and waterborne transmission routes. This study aimed to assess the prevalence of HEV in water matrices. Six categories were defined: untreated and treated wastewater, surface water (river, lake, and seawater), drinking water, groundwater, and other water environments (irrigation water, grey water, reservoir water, flood water, and effluent of pig slaughterhouse). We searched PubMed, Web of Science, Global Index Medicus, and Excerpta Medica Database. Study selection and data extraction were performed by at least two independent investigators. Heterogeneity (I²) was assessed using the χ² test on the Cochran Q statistic and H parameter. Sources of heterogeneity were explored by subgroup analysis. This study is registered with PROSPERO, number CRD42021289116. We included 87 prevalence studies from 58 papers, 66.4% of which performed in Europe. The overall prevalence of HEV in water was 9.8% (95% CI 6.4-13.7). The prevalence was higher in untreated wastewater (15.1%) and lower in treated wastewater (3.8%) and in drinking water (4.7%). In surface water, prevalence was 7.4%, and in groundwater, the percentage of positive samples, from only one study available, was 8.3%. Overall, only 36.8% of the studies reported the genotype of HEV, with genotype 3 (HEV-3) prevalent (168 samples), followed by HEV-1 (148 sample), and HEV-4 (2 samples). High-income countries were the most represented with 59/87 studies (67.8%), while only 3/87 (3.5%) of the studies were performed in low-income countries. The overall prevalence obtained of this study was generally higher in industrialized countries. Risk of bias was low in 14.9% of the studies and moderate in 85.1%. The results of this review showed the occurrence of HEV in different waters environments also in industrialized countries with sanitation and safe water supplies. While HEV transmission to humans through water has been widely demonstrated in developing countries, it is an issue still pending in industrialized countries. Better knowledge on the source of pollution, occurrence, survival in water, and removal by water treatment is needed to unravel this transmission path.

Assessment of the Presence of Hepatitis E virus in Surface Water and Drinking Water in Portugal

Hepatitis E virus (HEV) is a non-enveloped single-stranded positive-sense RNA virus, belonging to the Hepeviridae family, resistant to environmental conditions, and transmitted by the consumption of contaminated water. This virus is responsible for both sporadic and epidemic outbreaks, leading to thousands of infections per year in several countries, and is thus considered an emerging disease in Europe and Asia. This study refers to a survey in Portugal during 2019, targeting the detection and eventual quantification of enteric viruses in samples from surface and drinking water. Samples positive for HEV RNA were recurrently found by reverse transcription quantitative PCR (RT-qPCR), in both types of matrix. The infectivity of these samples was evaluated in cultured Vero E6 cells and RNA from putative viruses produced in cultures evidencing cytopathic effects and was subjected to RT-qPCR targeting HEV genomic RNA. Our results evidenced the existence of samples positive either for HEV RNA (77.8% in surface water and 66.7% in drinking water) or for infectious HEV (23.0% in surface water and 27.7% in drinking water). These results highlight the need for effective virological control of water for human consumption and activities.

Hepatitis E virus genotype 3 strains and a plethora of other viruses detected in raw and still in tap water

In this study, next generation sequencing was used to explore the virome in 20L up to 10,000L water from different purification steps at two Swedish drinking water treatment plants (DWTPs), and in tap water. One DWTP used ultrafiltration (UF) with 20 nm pores, the other UV light treatment after conventional treatment of the water. Viruses belonging to 26 different families were detected in raw water, in which 6-9 times more sequence reads were found for phages than for known environmental, plant or vertebrate viruses. The total number of viral reads was reduced more than 4-log10 after UF and 3-log10 over UV treatment. However, for some viruses the reduction was 3.5-log10 after UF, as for hepatitis E virus (HEV), which was also detected in tap water, with sequences similar to those in raw water and after treatment. This indicates that HEV had passed through the treatment and entered into the supply network. However, the viability of the viruses is unknown. In tap water 10-130 International Units of HEV RNA/mL were identified, which is a comparable low amount of virus. The risk of getting infected through consumption of tap water is probably negligible, but needs to be investigated. The HEV strains in the waters belonged to subtypes HEV3a and HEV3c/i, which is associated with unknown source of infection in humans infected in Sweden. None of these subtypes are common among pigs or wild boar, the major reservoirs for HEV, indicating that water may play a role in transmitting this virus. The results indicate that monitoring small fecal/oral transmitted viruses in DWTPs may be considered, especially during community outbreaks, to prevent potential transmission by tap water.

Hepatitis E virus: chronic infection, extra-hepatic manifestations, and treatment

Hepatitis E virus (HEV) infection is a worldwide disease. An improved understanding of the natural history of HEV infection has been achieved within the last decade. Several reservoirs and transmission modes have been identified. It is an underdiagnosed disease because of the use of low-sensitivity serological assays; however, diagnostics tools, including nucleic-acid tests, have improved. HEV infection is usually an acute self-limiting disease, but causes chronic infection with rapidly progressive cirrhosis in adult and pediatric organ-transplant-patients. HEV infection evolves to chronic hepatitis in nearly 60% of HEV-infection solid-organ-transplant patients. HEV can also cause extra-hepatic manifestations, such as neurological symptoms and kidney injury. Reducing immunosuppression in transplant patients can lead to HEV clearance in one-third of patients with chronic hepatitis. The use of anti-viral therapies, such as pegylated-interferon and ribavirin, has been found to efficaciously treat HEV infection.

Hepeviridae: an expanding family of vertebrate viruses

The hepatitis E virus (HEV) was first identified in 1990, although hepatitis E-like diseases in humans have been recorded for a long time dating back to the 18th century. The HEV genotypes 1-4 have been subsequently detected in human hepatitis E cases with different geographical distribution and different modes of transmission. Genotypes 3 and 4 have been identified in parallel in pigs, wild boars and other animal species and their zoonotic potential has been confirmed. Until 2010, these genotypes along with avian HEV strains infecting chicken were the only known representatives of the family Hepeviridae. Thereafter, additional HEV-related viruses have been detected in wild boars, distinct HEV-like viruses were identified in rats, rabbit, ferret, mink, fox, bats and moose, and a distantly related agent was described from closely related salmonid fish. This review summarizes the characteristics of the so far known HEV-like viruses, their phylogenetic relationship, host association and proposed involvement in diseases. Based on the reviewed knowledge, a suggestion for a new taxonomic grouping scheme of the viruses within the family Hepeviridae is presented.

Bioaccumulation efficiency, tissue distribution, and environmental occurrence of hepatitis E virus in bivalve shellfish from France

Hepatitis E virus (HEV), an enteric pathogen of both humans and animals, is excreted by infected individuals and is therefore present in wastewaters and coastal waters. As bivalve molluscan shellfish are known to concentrate viral particles during the process of filter feeding, they may accumulate this virus. The bioaccumulation efficiencies of oysters (Crassostrea gigas), flat oysters (Ostrea edulis), mussels (Mytilus edulis), and clams (Ruditapes philippinarum) were compared at different time points during the year. Tissue distribution analysis showed that most of the viruses were concentrated in the digestive tissues of the four species. Mussels and clams were found to be more sensitive to sporadic contamination events, as demonstrated by rapid bioaccumulation in less than 1 h compared to species of oysters. For oysters, concentrations increased during the 24-h bioaccumulation period. Additionally, to evaluate environmental occurrence of HEV in shellfish, an environmental investigation was undertaken at sites potentially impacted by pigs, wild boars, and human waste. Of the 286 samples collected, none were contaminated with hepatitis E virus, despite evidence that this virus is circulating in some French areas. It is possible that the number of hepatitis E viral particles discharged into the environment is too low to detect or that the virus may have a very short period of persistence in pig manure and human waste.

Characterization of hepatitis E virus from sporadic hepatitis cases and sewage samples from Vellore, south India

BACKGROUND

Hepatitis E virus (HEV) is endemic in India and causes epidemics and sporadic cases. However, the exact transmission route for sporadic hepatitis E remains unclear. This study investigated HEV in sporadic hepatitis cases and sewage samples, as sewage is the major source of contamination of water in developing countries.

METHODS

Monthly sampling and testing for HEV in sewage samples from Vellore, India was carried out for 1 year (November 2009-October 2010) and plasma and/or fecal samples from sporadic hepatitis cases presenting to a hospital in Vellore during 2006-2010 were tested for HEV RNA. A total of 144 raw sewage samples and 94 samples from sporadic hepatitis cases were tested for HEV RNA using RT-PCR.

RESULTS

The prevalence of HEV RNA in sewage and sporadic cases was 55.6% and 9.6%, respectively. HEV strains isolated from sewage showed 94-100% nucleotide sequence similarity with the HEV strains isolated from the sporadic hepatitis cases. HEV RNA in sewage was identified more often during the summer (81.2%) than the monsoon season (14.5%) (p < 0.001).

CONCLUSION

This study indicates that sewage may be a source of contamination for sporadic hepatitis and also underscores the need for preventive measures to protect drinking water from sewage contamination, particularly in the summer. GENBANK ACCESSION NUMBERS: HEV strains isolated from this study were deposited in GenBank under accession numbers JF972766-JF972773, JN705651-JN705659 and JN705660-JN705662.

Detection of hepatitis E virus (HEV) through the different stages of pig manure composting plants

Hepatitis E virus (HEV) is an increasing cause of acute hepatitis in industrialized countries. The aim of this study was to evaluate the presence of HEV in pig manure composting plants located in Spain. For this purpose, a total of 594 samples were taken in 54 sampling sessions from the different stages of composting treatment in these plants as follows: slurry reception ponds, anaerobic ponds, aerobic ponds, fermentation zone and composting final products. HEV was detected by reverse transcription polymerase chain reaction (RT-nested PCR) in four (80%) of five plants studied, mainly in the first stages of the process. HEV was not detected in any final product (compost) sample, destined to be commercialized as a soil fertilizer, suggesting that composting is a suitable method to eliminate HEV and thus, to reduce the transmission of HEV from pigs to humans.

Epidemiology of mammalian hepatitis E virus infection

Mammalian hepatitis E virus (HEV), the etiological agent of hepatitis E in humans, is a recently discovered infectious agent. It was identified for the first time in 1983 using electron microscopy on a faecal specimen of a person infected with non-A, non-B enterically-transmitted hepatitis. Based on retrospective and prospective studies, HEV was long described as one of the leading causes of acute viral hepatitis in tropical and subtropical countries, whereas in developed countries hepatitis E was considered an imported disease from HEV hyperendemic countries. Data from studies conducted during the past decade have greatly shifted our knowledge on the epidemiology and clinical spectrum of HEV. Recently, it has been shown that contrary to previous beliefs, hepatitis E is also an endemic disease in several developed countries, particularly in Japan and in Europe, as evidenced by reports of high anti-HEV immunoglobulin G prevalence in healthy individuals and an increasing number of non-travel-related acute hepatitis E cases. Moreover, a porcine reservoir and growing evidence of zoonotic transmission have been reported in these countries. This review summarizes the current knowledge on the epidemiology and prevention of transmission of mammalian HEV.

Hepatitis E: source and route of infection, clinical manifestations and new developments

Hepatitis E was previously thought to be a disease of developing countries causing significant morbidity and mortality in young adults, particularly among pregnant women and patients with pre-existing chronic liver disease. Recent studies have shown that hepatitis E is also an issue in developed countries. In this setting, hepatitis E is a zoonotic infection and causes acute infection mainly in middle-aged and elderly men; and chronic infection in the immunosuppressed. The scope and burden of disease are still emerging. The diagnosis of hepatitis E should be considered in any patient with hepatitis, irrespective of their age or travel history.

Increased risk of hepatitis E virus infection in schizophrenia

Until now, the risk of HEV infection in schizophrenia was unknown. The present results showed that the seroprevalence of anti-HEV IgG and anti-HEV IgM in schizophrenia were significantly higher than that in healthy controls. Anti-HEV IgG positivity increased with age and with the duration of disease in schizophrenia patients. Moreover, schizophrenia patients with increased CD4⁺/CD8⁺ T-cell ratios (>2.03) had higher anti-HEV IgG detection rates than those with normal ratios (1.05-2.03). Compared with the schizophrenia patients who tested anti-HEV IgG negative, the levels of interleukin-4 and interleukin-10 (Th2 cytokines) were significantly higher, while the interleukin-12 (Th1 cytokine) level was significantly lower, in those with anti-HEV IgG positivity. Of five schizophrenia patients who were anti-HEV IgM positive, four had elevated CD4⁺/CD8⁺ T-cell ratios. HEV RNA was isolated from one of these four patients and classified as genotype 4. Anti-HEV IgM positivity was not detected among healthy controls. Therefore, schizophrenia patients exhibited a higher risk of HEV infection than controls.

Transfusion-transmitted hepatitis E: is screening warranted?

Hepatitis E virus (HEV) is an emerging infectious threat to blood safety. In recent years, there have been a number of publications delineating this threat by providing evidence of the transmissibility of this virus through transfusions. The extent of transmission and its clinical relevance are issues under debate at present. HEV usually causes a self-limiting illness which subsides in a few weeks barring a few cases where fulminant hepatic failure occurs. The virus poses a risk of higher morbidity and mortality in pregnant females, patients with pre-existing liver disease and solid organ transplant recipients. As these categories of patient often require repeated transfusions or massive transfusions, they are exposed to a greater risk of transmission of HEV. At present, there is little evidence to advocate universal screening for this virus but considering that there is no definitive treatment for HEV induced hepatitis, selective screening should be advocated in blood products for high risk recipients in endemic areas.

Survival of hepatitis A and E viruses in soil samples

Survival of hepatitis A virus (HAV) and hepatitis E virus (HEV) in soil samples spiked with respective viruses was analysed using real-time PCR. Virus-spiked soil samples were incubated at environmental temperature (ET) and 37°C and processed weekly. Both HAV and HEV were less stable at fluctuating ET than at 37°C. Of the 403 soil samples collected in the vicinity of Mutha river, India, 19.1% and 4.9% were found to be contaminated with HAV and HEV, respectively.

Hepatitis E virus infection in developed countries

Hepatitis E was considered to be endemic infectious disease in developing countries in tropical or subtropical regions with poor sanitary conditions. Large, previously reported outbreaks were mainly due to contaminated water or heavy flooding. Prototype hepatitis E viruses of genotypes I and II were obtained from such endemic cases. In developed countries, in contrast, hepatitis E was rare and diagnosed only in travelers or imported cases. However, the development of accurate diagnostic tests, mainly PCR detection elucidated that autochthonous hepatitis E in developed countries is far more common than previously thought. Although the main route of transmission is food-borne, other routes including blood-borne have been suggested. Recent developments of gene-based diagnostic assays and molecular epidemiology have disclosed the significance of hepatitis E virus infection in developed countries.