Hepatitis E virus (HEV) infection in haemodialysis patients. The Multicentre Haemodialysis Cohort Study on Viral Hepatitis

Hepatitis E Virus (HEV) Infection among Hemodialysis Patients from Southern Bulgaria

Viral hepatitis B and C are widely recognized problems in hemodialysis (HD) patients. There have been increasing reports of the importance of the hepatitis E virus (HEV) in recent years, but the worldwide data on the seroprevalence of HEV among them are conflicting. The aim of the present study was to assess the seroprevalence of HEV in HD patients and to analyze the predictors of seropositivity. This study was conducted in 2020 in the central part of southern Bulgaria. A total of 225 patients were enrolled. An enzyme-linked immunosorbent assay for the determination of anti-HEV IgM/IgG was used. All patients were tested for the presence of HEV RNA. Anti-HEV IgM alone and anti-HEV IgG alone were found in 6 (2.7%) and 14 (6.2%) patients, respectively, and in 4 (1.8%) patients, they were found simultaneously. All patients were HEV RNA-negative. The overall HEV seroprevalence was 10.7% (24/225). The binominal logistic regression analysis of available predictors confirmed the role of vascular access and a duration of dialysis treatment over 5 years as predictors significantly associated with increased risk for HEV, and the consumption of bottled water with lower levels of HEV IgG seroprevalence among hemodialysis patients. The accumulated data are the basis for comparative analysis in subsequent trials in the same dialysis centers and for enhancing the range of screening markers used in this particular patient group.

Hepatitis E Virus (HEV) Infection in Hemodialysis Patients: A Multicenter Epidemiological Cohort Study in North-Eastern Greece

Hepatitis E virus (HEV), a common cause of viral hepatitis in developing countries, is mainly transmitted via the fecal-oral route, but also may be a prevalent hospital-transmitted agent among patients on regular hemodialysis due to parenteral transmission. Previous epidemiological studies among hemodialysis patients in Greece, using different diagnostic techniques, gave conflicting results. Τhe present study aimed to measure the exposure rate of hemodialysis patients of north-eastern Greece to HEV by estimating the overall seroprevalence, and to identify potential risk factors. Serum samples from all patients attending the hemodialysis centers of north-eastern Greece (n = 6) were tested for the presence of anti-HEV IgG antibodies using a modern and sensitive ELISA (Enzyme-linked Immunosorbent Assay) technique (Wantai). In total, 42 out of 405 hemodialysis patients were positive for anti-HEV IgG (10.4%), while all samples were negative for HEV RNA when tested using nested RT-PCR. HEV seropositivity among hemodialysis patients was significantly associated with area of residence and contact with specific animals (pork, deer). No association was found with religion, gender distribution and hemodialysis duration. This study showed an increased seroprevalence of HEV among hemodialysis patients in Greece. Agricultural or livestock occupation and place of residence seem to be independent factors that increase the risk of HEV infection. In conclusion, HEV infection calls for the regular screening of hemodialysis patients regardless of the hemodialysis duration or clinical symptoms.

Seroepidemiology of hepatitis E virus infection in patients undergoing maintenance hemodialysis: Systematic review and meta-analysis

Patients undergoing regular hemodialysis (HD) are at an extreme risk of acquiring bloodstream infections compared to the general population. Hepatitis E virus (HEV) infection is an important emerging health issue in these patients. To date, numerous studies have investigated the seroprevalence of HEV among HD patients across the world; however, the data are conflicting. The present study aimed to measure the exposure rate of HD patients to HEV infection by estimating the overall seroprevalence of HEV in this high-risk group. A systematic literature search was carried out using five electronic databases from inception to January 10, 2020, with standard keywords. Pooled seroprevalence estimates with 95% confidence intervals (CIs) were calculated using a random intercept logistic regression model. The seroprevalence of HEV increased from 6.6% between the years of 1994 and 2000 to 11.13% from 2016 to 2020. Blood transfusion was associated with a nearly 2-fold increase in the rate of HEV seropositivity (OR = 1.99; 95% CI: 1.50-2.63, P < .0001, I² = 6.5%). HEV seroprevalence among patients with HD for more than 60 months was significantly higher than those with HD for less than 60 months (27.69%, 95% CI: 20.69%-35.99% vs 15.78%, 95%CI: 8.85%-26.57%, respectively) (P = .06). Our results indicated increased exposure of HD patients with HEV infection over the last decade. We concluded that blood transfusion and duration of HD are considerable risk factors for acquiring HEV infection among HD patients.

Prevalence of anti-hepatitis E virus IgG antibodies in sera from hemodialysis patients in Tripoli, Lebanon

Hepatitis E virus (HEV) is an important global public health concern. Several studies reported a higher HEV prevalence in patients undergoing regular hemodialysis (HD). In Lebanon, the epidemiology of HEV among HD patients has never been investigated previously. In this study, we examine the seroprevalence of HEV infection among 171 HD patients recruited from three hospital dialysis units in Tripoli, North Lebanon. Prevalence of anti-HEV IgG antibodies was evaluated in participant's sera using a commercial enzyme-linked immunosorbent assay (ELISA). The association of socio-demographic and clinical parameters with HEV infection in patients was also evaluated. Overall, 96 women and 75 men were enrolled in this study. Anti-HEV IgG antibodies were found positive in 37/171 HD patients showing a positivity rate of 21.63%. Among all examined variables, only the age of patients was significantly associated with seropositivity (P = 0.001). This first epidemiological study reveals a high seroprevalence of HEV infection among Lebanese HD patients. However, further evaluations that enroll larger samples and include control groups are required to identify exact causative factors of the important seropositivity rate in this population.

Implications of Hepatitis E Virus in Blood Transfusions, Hemodialysis, and Solid Organ Transplants

Hepatitis E Virus (HEV) is emerging as the primary cause of acute viral hepatitis in humans. The virus is commonly transmitted by the fecal-oral route via contaminated water in endemic regions or through the consumption of inadequately cooked swine products or game meats in industrialized regions. HEV genotypes 1 and 2 are predominantly associated with waterborne transmission in developing countries, whereas HEV3 and HEV4 are mainly zoonotically transmitted in industrialized countries. Seroprevalence in populations determined by detecting anti-HEV antibodies and serum HEV RNA is commonly used to analyze the presence of HEV. Although HEV RNA-based detection is now standardized, there is a lack of agreement between the assaying methods used for gathering seroprevalence data. Since 2004, HEV has been considered as a transmissible infectious agent through blood transfusion. Recent seroprevalence studies in European countries indicate an underestimated risk for blood transfusion and hence warrant testing the blood supply. HEV infection is usually self-limiting and spontaneously cleared. However, in about 60% of recipients of solid organ transplants, HEV progresses to chronic hepatitis. Immunosuppressive drugs such as tacrolimus are a major cause of chronic hepatitis and reducing its dosage results in viral clearance in about 30% of patients. In hemodialysis patients, the parenteral route is implicated as an important mechanism of transmission. In this review, we explore the clinical and epidemiological characteristics of various HEV genotypes in blood donors, hemodialysis patients, and transplant recipients.

Hepatitis E in hemodialysis and kidney transplant patients in south-east Italy

AIM: To investigate the serovirological prevalence and clinical features of hepatitis E virus (HEV) infection in end-stage renal failure patients and in the healthy population.

METHODS: HEV infection is a viral disease that can cause sporadic and epidemic hepatitis. Previous studies unexpectedly showed a high prevalence of HEV antibodies in immunosuppressed subjects, including hemodialysis (HD) patients and patients who had undergone kidney transplant. A cohort/case-control study was carried out from January 2012 to August 2013 in two hospitals in southern Italy (Foggia and S. Giovanni Rotondo, Apulia). The seroprevalence of HEV was determined in 801 subjects; 231 HD patients, 120 renal transplant recipients, and 450 health individuals. All HD patients and the recipients of renal transplants were attending the Departments of Nephrology and Dialysis at two hospitals located in Southern Italy, and were included progressively in this study. Serum samples were tested for HEV antibodies (IgG/IgM); in the case of positivity they were confirmed by a Western blot assay and were also tested for HEV-RNA, and the HEV genotypes were determined.

RESULTS: A total of 30/801 (3.7%) patients were positive for anti-HEV Ig (IgG and/or IgM) and by Western blot. The healthy population presented with a prevalence of 2.7%, HD patients had a prevalence of 6.0%, and transplant recipients had a prevalence of 3.3%. The overall combined HEV-positive prevalence in the two groups with chronic renal failure was 5.1%. The rates of exposure to HEV (positivity of HEV-IgG/M in the early samples) were lower in the healthy controls, but the difference among the three groups was not statistically significant (P > 0.05). Positivity for anti-HEV/IgM was detected in 4/30 (13.33%) anti-HEV Ig positive individuals, in 2/14 HD patients, in 1/4 transplant individuals, and in 1/12 of the healthy population. The relative risk of being HEV-IgM-positive was significantly higher among transplant recipients compared to the other two groups (OR = 65.4, 95%CI: 7.2-592.7, P < 0.001), but the subjects with HEV-IgM positivity were numerically too few to calculate a significant difference. No patient presented with chronic hepatitis from HEV infection alone.

CONCLUSION: This study indicated a higher, but not significant, circulation of HEV in hemodialysis patients vs the healthy population. Chronic hepatitis due to the HEV virus was not observed.

Epidemiology of hepatitis e virus infection in patients on chronic hemodialysis

Background:

Many studies have been done on the epidemiology of Hepatitis E on general population, but the data among patients with end stage renal disease (ESRD) are few and give conflicting results.

Objectives:

The aim of this study was to investigate the prevalence of hepatitis E virus (HEV) infection and its relationship in ESRD patients undergoing maintenance hemodialysis (HD).

Patients and Methods:

This cross-sectional study was carried out on ESRD patients treated with HD in Imam Khomeini Hospital, Ahvaz city, Southwest of Iran. Blood sampling of patients was collected immediately before the dialysis session and the serum were evaluated for anti-HEV IgG titers by enzyme-linked immunosorbent assays. The statistical package for social sciences (SPSS) version 15 software was used for data analysis.

Results:

Out of 47 ESRD patients, 27 were male (57.4%) and 20 were female (42.6%), with mean age of 55.27 ± 8.1 years. The prevalence of anti-HEV antibody was 10.6 % (five patients, four male and one female). The mean age of HEV positive and negative patients were 58 ± 5.52 and 53.82 ± 15.55 years, respectively without any significant difference (P = 0.058). There also was no significant association between HEV and gender (P = 0.28). The mean time of HD in HEV positive and negative patients were 1224.2 and 1168.5 days, respectively with no significant association (P = 0.88). In addition, there also was no association between HEV and HCV (P = 0.61).

Conclusions:

According to the present study, the prevalence of anti-HEV IgG antibody was 10.63 % among chronic HD patients and there was no association between HEV, age, gender, duration of HD and HCV antibody titer.

Host immune status and response to hepatitis E virus infection

Hepatitis E virus (HEV), identified over 30 years ago, remains a serious threat to life, health, and productivity in developing countries where access to clean water is limited. Recognition that HEV also circulates as a zoonotic and food-borne pathogen in developed countries is more recent. Even without treatment, most cases of HEV-related acute viral hepatitis (with or without jaundice) resolve within 1 to 2 months. However, HEV sometimes leads to acute liver failure, chronic infection, or extrahepatic symptoms. The mechanisms of pathogenesis appear to be substantially immune mediated. This review covers the epidemiology of HEV infection worldwide, the humoral and cellular immune responses to HEV, and the persistence and protection of antibodies produced in response to both natural infection and vaccines. We focus on the contributions of altered immune states (associated with pregnancy, human immunodeficiency virus [HIV], and immunosuppressive agents used in cancer and transplant medicine) to the elevated risks of chronic infection (in immunosuppressed/immunocompromised patients) and acute liver failure and mortality (among pregnant women). We conclude by discussing outstanding questions about the immune response to HEV and interactions with hormones and comorbid conditions. These questions take on heightened importance now that a vaccine is available.

Hepatitis E seroprevalence in recipients of renal transplants or haemodialysis in southwest England: a case-control study

Locally acquired HEV infection is increasingly recognized in developed countries. Anti-HEV IgG seroprevalence has been shown to be high in haemodialysis patients in a number of previous studies, employing assays of uncertain sensitivity. The aim of this study was to investigate anti-HEV IgG seroprevalence in recipients of haemodialysis and renal transplants compared to a control group using a validated, highly sensitive assay. Eighty-eight patients with functioning renal transplants and 76 receiving chronic haemodialysis were tested for HEV RNA and anti-HEV IgG and IgM. Six hundred seventy controls were tested for anti-HEV IgG. Anti-HEV IgG was positive in 28/76 (36.8%) of haemodialysis and 16/88 (18.2%) of transplant patients. HEV RNA was not found in any patient. 126/670 (18.8%) of control subjects were anti-HEV IgG positive. After adjusting for age and sex, there was a significantly higher anti-HEV IgG seroprevalence amongst haemodialysis patients compared to controls (OR = 1.97, 95% CI = 1.16-3.31, P = 0.01) or transplant recipients (OR = 2.63, 95% CI = 1.18-6.07, P = 0.02). Patients with a functioning transplant showed no difference in anti-HEV IgG seroprevalence compared to controls. The duration of haemodialysis or receipt of blood products were not significant risk factors for HEV IgG positivity. Patients receiving haemodialysis have a higher seroprevalence of anti-HEV IgG than both age- and sex-matched controls and a cohort of renal transplant patients. None of the haemodialysis patients had evidence of chronic infection. The reason haemodialysis patients have a high seroprevalence remains uncertain and merits further study.

Prevalence of hepatitis E virus infection in regular hemodialysis patients

The percentage of patients infected with blood-borne diseases, including hepatitis B virus (HBV) and hepatitis C virus (HCV) infections, is high in patients undergoing hemodialysis regularly. Hepatitis E virus (HEV) is transmitted via the fecal-oral route, and blood-borne HEV infection has also been reported recently. On the basis of these findings, we investigated the actual status of HEV infection in regular hemodialysis patients. Out of 1077 patients undergoing hemodialysis at two key hospitals and three outpatient hemodialysis clinics, 300 were randomly selected as the subjects. Among these 300 hemodialysis patients, 19.0% were IgG-type anti-HEV antibody-positive. The percentage of HEV-infected patients increased with patient age and it was particularly high in patients 40 years of age or older. The percent IgG-type anti-HEV antibody positivity was not significantly different (P = 0.14) between anti-HCV antibody-positive patients (27.8%) and anti-HCV antibody-negative patients (17.8%). The percentage of HEV-infected patients among the hemodialysis patients was higher than that previously reported among patients with healthy kidneys. No correlation was observed between the percentage of HEV-infected patients and HCV infection incidence or a history of blood transfusion. The percent IgG-type anti-HEV antibody positivities were significantly different among the facilities. It was impossible to specify the route of infection, and the correlation between the incidence of infection and hemodialysis therapy was not clear. Because more routes of infection are possible for patients undergoing dialysis than for persons with normal kidney function, it seems necessary to analyze the significance of infection incidence, the route of infection and infection prevention measures.

Human Herpesvirus 8 Infection in Hemodialysis Patients

BACKGROUND

The aim of the present study was to evaluate human herpesvirus 8 (HHV-8) seroprevalence in Greek hemodialysis patients. Patterns of change in HHV-8 serostatus (seroconversions and seroreversions) over time were also evaluated.

METHODS

Serum samples obtained from a cohort of 485 Greek hemodialysis patients were tested for antibodies to HHV-8 by whole virus lysate enzyme-linked immunosorbent assay, and reactive samples were confirmed by means of the orf-73 enzyme-linked immunosorbent assay. HHV-8 seroprevalence at study entry and the incidence of seroreversions and seroconversions per 100 person-years were estimated.

RESULTS

The prevalence of HHV-8 antibodies in Greek hemodialysis patients at enrollment was 7.2%. No univariate associations were established between HHV-8 serostatus and patients' characteristics. Incidences of seroreversions and seroconversions were 16.4/100 person-years (95% confidence interval, 7.1 to 32.3) and 0.28/100 person-years (95% confidence interval, 0.03 to 1.02), respectively. Patients 50 years and younger had an increased probability for seroreversion to HHV-8 antibodies than patients older than 50 years (log-rank test, P = 0.018).

CONCLUSION

We observed a fair number of seroreversions and a low incidence of seroconversion to HHV-8 infection in hemodialysis patients in Greece. Our data provide indirect evidence that HHV-8 transmission in the hemodialysis setting is uncommon.

Acute hepatitis and renal function impairment related to infection by hepatitis E virus in a renal allograft recipient

Clinicians often are faced with an increase in liver enzyme levels. In the majority of cases, the cause is found rapidly. Conversely, in a few cases, the etiologic agent remains unknown and requires either liver biopsy or drug-medication modification. We report a case of acute icteric hepatitis associated with renal function impairment related to infection caused by primary hepatitis E virus (HEV) in a renal transplant recipient who lived in a nonclassic endemic area and had not traveled abroad. Clinicians must be aware that in cases of unexplained hepatitis in organ transplant recipients and in the absence of evident drug hepatotoxicity, HEV should be considered as an etiologic agent for hepatitis. Subsequently, HEV serological tests should be performed, HEV RNA should be looked for in acute-phase serum and stool samples, and liver parameters should be monitored closely because HEV might be responsible, in some cases, for fulminant hepatitis.

Hepatitis E virus infection in hemodialysis patients: a seroepidemiological survey in Iran

BACKGROUND

The hepatitis E virus (HEV) has a global distribution and is known to have caused large waterborne epidemics of icteric hepatitis. Transmission is generally via the fecal-oral route. Some reports have suggested parenteral transmission of HEV. Anti-HEV prevalence data among chronic hemodialysis (HD) patients are few and give conflicting results.

METHODS

This cross-sectional study was conducted in August of 2004. We tested 324 chronic HD patients attending three different units in the city of Tabriz, northwestern part of Iran, for anti-HEV antibody. A specific solid- phase enzyme-linked immunoassay (Diapro, Italy) was used.

RESULTS

The overall seroprevalence of hepatitis E was 7.4 %(95% CI: 4.6%-10.6%). The prevalence rate of HBV and HCV infection were 4.6% (95% CI: 2.3%-6.9%) and 20.4% (95% CI: 16%-24.8%), respectively. No significant association was found between anti-HEV positivity and age, sex, duration of hemodialysis, positivity for hepatitis B or C virus infection markers and history of transfusion.

CONCLUSION

We observed high anti-HEV antibody prevalence; there was no association between HEV and blood borne infections (HBV, HCV, and HIV) in our HD patients. This is the first report concerning seroepidemiology of HEV infection in a large group of chronic HD individuals in Iran.

Hepatitis E virus antibodies in hemodialysis patients: an epidemiological survey in central Greece

Hepatitis E virus (HEV) is the causative agent for enteric non-A, non-B hepatitis. Transmission is mainly via the fecal-oral route but the possibility of an additional parenteric transmission has been raised. Patients undergoing chronic hemodialysis (HD) have an increased risk of exposure to blood transmitted agents. Previous studies concerning prevalence of antibodies to HEV (anti-HEV) among HD patients gave conflicting results. The aim of the study presented here was to determine the prevalence of anti-HEV among HD patients of a well-defined semi-rural region in central Greece (Thessalia region). All patients (n=351, 234 males, mean age 60+/-14 years) who were being treated in the HD units of central Greece (n=5) during 2001 were tested for anti-HEV antibody. Two commercially available specific solid-phase enzyme-linked immunoassays were applied for anti-HEV detection. Hepatitis B virus markers, antibodies to HCV, HIV and HTLV were also screened in all patients by commercially available assays. Serum aminotransferase (AST, ALT) levels were measured by spectrophotometry. 17 anti-HEV-positive patients were found and prevalence was 4.8%, varying from 1.8 - 9.8% in the various HD units. Prevalence of HBsAg and anti-HCV was 5.7% (2.9 - 15%) and 23.6% (11.5 - 36.2%) respectively. The anti-HEV prevalence was increased compared to healthy blood donors in Greece (0.26%, p < 0.01). The highest prevalence of anti-HEV was seen at the HD unit of the General Hospital of Karditsa (9.8%). Risk factors for anti-HEV antibody were not identified: no association was found between anti-HEV positivity and age or sex, duration of HD, hepatitis B or C virus infection markers, previously elevated aminotransferase levels or history of transfusion. Our investigation of HEV infection in the cohort of HD patients in central Greece showed that the prevalence of anti-HEV was greater than in healthy blood donors. There was no association to blood borne infections (HBV, HCV). The high prevalence of anti-HEV we found in one HD unit was probably related to a local infection in the past. However, long-term prospective studies are needed in an attempt to identify whether intra-unit factors are also responsible for the increased prevalence of serologic markers of HEV infection among HD patients.

Prevalence of hepatitis E virus infection among hemodialysis patients in Japan: Evidence for infection with a genotype 3 HEV by blood transfusion

To investigate the prevalence of hepatitis E virus (HEV) infection among patients on maintenance hemodialysis, serum samples collected in January 2003 from 416 patients who had been undergoing hemodialysis for 7.6 +/- 6.3 (mean +/- standard deviation) (range, 0.3-26.0) years in a dialysis unit in Japan and serum samples that had been collected from these patients at the start of hemodialysis were tested for IgG antibodies to HEV (anti-HEV IgG) by an "in-house" enzyme-linked immunosorbent assay (ELISA). Overall, 39 patients (9.4%) had anti-HEV IgG in January 2003, and included 35 patients (8.4%) who had already been positive for anti-HEV IgG at the start of hemodialysis and 4 patients (1%) who seroconverted after initiation of hemodialysis. Periodic serum samples that had been collected from the four seroconverted patients were tested for HEV antibodies and HEV RNA. The four patients became positive for anti-HEV IgG in 1979, 1980, 1988, or 2003, and continued to be seropositive until the end of the observation period. Although anti-HEV IgM was not detectable in the four patients, three were infected transiently with apparently Japanese indigenous HEV strains of genotype 3. The patient who contracted HEV infection in 1979 had been transfused with 2 U of blood 21 days before the transient viremia: one of the two stored pilot serum samples had detectable HEV RNA with 100% identity to that recovered from the patient. Our study provides evidence of transfusion-transmitted HEV infection in Japan in 1979, and that the prevalence of de novo HEV infection during hemodialysis was low (1.1% or 4/374).

Evidence of extrahepatic sites of replication of the hepatitis E virus in a swine model

Hepatitis E virus (HEV) is the major cause of enterically transmitted non-A, non-B hepatitis in many developing countries and is also endemic in many industrialized countries. Due to the lack of an effective cell culture system and a practical animal model, the mechanisms of HEV pathogenesis and replication are poorly understood. Our recent identification of swine HEV from pigs affords us an opportunity to systematically study HEV replication and pathogenesis in a swine model. In an early study, we experimentally infected specific-pathogen-free pigs with two strains of HEV: swine HEV and the US-2 strain of human HEV. Eighteen pigs (group 1) were inoculated intravenously with swine HEV, 19 pigs (group 2) were inoculated with the US-2 strain of human HEV, and 17 pigs (group 3) were used as uninoculated controls. The clinical and pathological findings have been previously reported. In this expanded study, we aim to identify the potential extrahepatic sites of HEV replication using the swine model. Two pigs from each group were necropsied at 3, 7, 14, 20, 27, and 55 days postinoculation (DPI). Thirteen different types of tissues and organs were collected from each necropsied animal. Reverse transcriptase PCR (RT-PCR) was used to detect the presence of positive-strand HEV RNA in each tissue collected during necropsy at different DPI. A negative-strand-specific RT-PCR was standardized and used to detect the replicative, negative strand of HEV RNA from tissues that tested positive for the positive-strand RNA. As expected, positive-strand HEV RNA was detected in almost every type of tissue at some time point during the viremic period between 3 and 27 DPI. Positive-strand HEV RNA was still detectable in some tissues in the absence of serum HEV RNA from both swine HEV- and human HEV-inoculated pigs. However, replicative, negative-strand HEV RNA was detected primarily in the small intestines, lymph nodes, colons, and livers. Our results indicate that HEV replicates in tissues other than the liver. The data from this study may have important implications for HEV pathogenesis, xenotransplantation, and the development of an in vitro cell culture system for HEV.

A review of hepatitis E virus

Hepatitis E virus (HEV) is a major cause of outbreaks and sporadic cases of viral hepatitis in tropical and subtropical countries but is infrequent in industrialized countries. The virus is transmitted by the fecal-oral route with fecally contaminated drinking water being the usual vehicle. Hepatitis resulting from HEV infection is a moderately severe jaundice that is self-limiting in most patients. Young adults, 15 to 30 years of age, are the main targets of infection, and the overall death rate is 0.5 to 3.0%. However, the death rate during pregnancy approaches 15 to 25%. Death of the mother and fetus, abortion, premature delivery, or death of a live-born baby soon after birth are common complications of hepatitis E infection during pregnancy. Hepatitis E virus is found in both wild and domestic animals; thus, HEV is a zoonotic virus. The viruses isolated from swine in the United States or Taiwan are closely related to human HEV found in those areas. The close genetic relationship of the swine and human virus suggests that swine may be a reservoir of HEV. In areas where swine are raised, swine manure could be a source of HEV contamination of irrigation water or coastal waters with concomitant contamination of produce or shellfish. Increasing globalization of food markets by industrialized countries has the potential of introducing HEV into new areas of the world. The purpose of this review is to cover certain aspects of hepatitis E including the causative agent, the disease, diagnosis, viral detection, viral transmission, epidemiology, populations targeted by HEV, and the role of animals as potential vectors of the virus.

Prevalence of antibodies to hepatitis E virus among hemodialysis patients in Sweden

In order to study the prevalence of antibody to hepatitis E virus (HEV) among hemodialysis patients and to evaluate whether chronic hemodialysis is associated with an increased risk of exposure to HEV in developed countries, the IgG anti-HEV was determined in serum samples obtained from 182 patients on chronic hemodialysis and 349 statistically selected, healthy Swedish control subjects. Serum specimens from 11 of the 182 (6.0%) hemodialysis patients and from 18 of the 349 (5.2%) control subjects were repeatedly positive for HEV antibodies (the difference was not significant: P = .67). Analysis of serial serum samples obtained at the initiation of hemodialysis and consecutively during follow-up periods of several years demonstrated no IgG anti-HEV seroconversion during chronic hemodialysis. The seroprevalence of anti-HEV antibody in the adult Swedish population was associated significantly with age. In persons younger than 40 years, the percentage of seropositive individuals was 2.5%, whereas the seroprevalence rate of anti-HEV was 7.4% in subjects older than 40 years (P < .05). This study indicates that nosocomial transmission of HEV to patients on maintenance hemodialysis was non-existent in three dialysis centers in Sweden (a developed country) and that chronic hemodialysis is not associated with an increased risk of exposure to HEV infection in this region.