Prevalence Of anti-HEV Research Articles

Seroprevalence of antibodies to hepatitis E virus in two large communities in Havana, Cuba

Hepatitis E virus (HEV) infection is an important cause of acute viral hepatitis in tropical and sub-tropical regions that occurs both as epidemic episodes and sporadic cases. The aim of this investigation was to estimate the prevalence of total immunoglobulin (Ig) anti-hepatitis E virus (anti-HEV) and the risk factors associated to two communities in Havana City. Serum samples (n=469) obtained from healthy individuals with no history of viral hepatitis were screened for total anti-HEV by enzyme immunoassay (EIA). An overall prevalence of 10% (47/469) (95% CI; 7.52-13.19%) was obtained. Higher anti-HEV prevalence was found in the municipality of Marianao (12.1%) compared to Playa (7.1%). Analysis of risk factors revealed a significant association of total anti-HEV prevalence in age group 41-60 years old, with a risk ratio of 3.21 (95% CI: 1.09-9.7) (P=0.01). No relation was found between anti-HEV and other variables such as gender, risk occupations, surgery and transfusions. The detection of total anti-HEV in individuals with no overt acute hepatitis suggests the existence of sub-clinical or anicteric HEV infection in these municipalities.

A nationwide survey for prevalence of hepatitis E virus antibody in qualified blood donors in Japan

In previous studies, we reported the transmission of hepatitis E virus (HEV) by transfusion, and the frequent detection of HEV markers in Japanese blood donors with elevated ALT levels. For the current study, we carried out a nationwide survey of the prevalence of IgG anti-HEV in qualified blood donors throughout Japan. The 12,600 samples from qualified blood donors were collected from seven blood centres (1800 per centre) representing nearly all regions of Japan. Samples were from age- and sex-matched blood donors who tested negative for all the current blood screening tests. The samples were screened using the in-house IgG anti-HEV ELISA. Sequentially, the positive samples were tested by the commercial IgG anti-HEV ELISA. Of 12,600 samples, 431 (3·4%) were regarded as positive for IgG anti-HEV. The prevalence of IgG anti-HEV was higher in eastern Japan (5·6%) than in western Japan (1·8%) (P<0·001), and was also age-dependent and higher in men (3·9%) than in women (2·9%) (P=0·002). The spread of the domestic infection of HEV was observed in qualified blood donors in Japan. A higher prevalence of IgG anti-HEV was observed in male donors, older donors and in donors residing in eastern Japan. Further studies are necessary to clarify the potential risk of transfusion-transmission of HEV in Japan.

Hepatitis E virus (HEV) genotype and the prevalence of anti-HEV in 8 species of animals in the suburbs of Beijing

To investigate the prevalence of anti-hepatitis E virus (HEV) and genotypes of hepatitis E virus in 8 species of animals including swine, cattle, sheep, horse, donkey, dog, chicken and duck in the suburb of Beijing. Serum samples were collected from the 8 species of animals, and fecal samples of younger swine were collected from 2 stock farms. Anti-HEV was detected by Double Antigen Sandwich Assay. HEV RNA from fecal samples was detected by a reverse transcription nested polymerase chain reaction (RT-nPCR). Parts of the PCR products were cloned and sequenced. The swine HEV sequences were analyzed genetically. The positive rates of anti-HEV in serum specimens of swine, cattle, horse, donkey, sheep, dog, duck and chicken were 80.43% (481/598), 15.02% (52/346), 14.29% (40/280), 0 (0/26), 9.88% (33/334), 0 (0/21), 3.03% (7/231) and 2.53% (8/316), respectively. The anti-HEV prevalence of adult swine (>/= 6 months) and younger swine ( < / = 3 months) were 87.86% (369/420) and 62.92% (112/178) respectively. 74 of 111 (66.67%) pig faces were positive for HEV RNA. Sequence analysis on these positive samples showed that there were 6 groups of HEV designated as bjsw1, bjsw2, bjsw3, bjsw4, bjsw5 and bjsw6. The 6 strains of HEV shared 94.5% - 99.6% sequence identity of partial HEV ORF2 nucleotide with each other. The identities of HEV ORF2 nucleotide sequences between the 6 strains and genotype 1, 2, 3 and 4 were 75.6% - 78.6%, 75.6% - 76.2%, 77.1% - 80.7% and 83.7% - 94.5%, respectively. The sequence identity between the 6 strains and human HEV genotype 4d was 90.0% - 94.5%. HEV infection was seen in swine, cattle, horse, sheep, duck and chicken in the suburbs of Beijing. The anti-HEV positive rate appeared the highest in swine and the lowest in dog and donkey. The six strains of HEV isolated from younger swine belonged to genotype 4d.

Epidemiological study of hepatitis E virus infection in the general population of Okinawa, Kyushu, Japan

The aim of this study was to investigate the prevalence of hepatitis E virus (HEV) infection in the general population of Japan by determining presence of the antibody to HEV (anti-HEV). The prevalence of HEV infection was determined by positivity of serum antibody to HEV (anti-HEV). On retrospective analysis, a significant decrease in anti-HEV prevalence was found in Okinawa healthy residents from 1995 (15.8%) to 2005 (5.5%) (P < 0.0001). In 2005, the anti-HEV prevalence was significantly higher in Okinawa wild boar hunters (25.3%) than in the residents (male 7.7% and female 4.1%) (P < 0.0001). A significant difference was found in the history of consumption of undercooked or raw boar meat between anti-HEV positive and negative hunters (100% vs 64.3%) (P = 0.0018). In conclusion, the anti-HEV prevalence has decreased in the residents of this area, but HEV infection has continued at a high rate in the hunters through the custom of eating undercooked or raw boar meat.

Hepatitis E Virus Genotype 1, Cuba

Hepatitis E Virus Genotype 1, Cuba

Unexpected high prevalence of IgG-antibodies to hepatitis E virus in Swedish pig farmers and controls

Hepatitis E virus (HEV) infections are responsible for large waterborne outbreaks in developing countries. Sporadic cases in the developed world are mainly imported via immigrants and travellers from endemic areas. HEV has been suggested to be a zoonotic infection where pigs may be an important reservoir for the disease and specific swine strains of HEV have been identified which can infect also humans. The aim of this study was to analyse if Swedish pig farmers are more exposed to HEV than persons with other occupations. A total of 115 male pig farmers aged 40-60 y and 108 age- and geographically- matched control subjects were tested for IgG anti-HEV antibodies. No statistical difference in anti-HEV prevalence was noted between pig farmers (13.0%) and control subjects (9.3%). The prevalence of anti-HEV antibodies in the pig farmers and controls was higher than that previously reported among other populations in Europe (<1-9%). Further studies are needed to elucidate the routes for infection of indigenous HEV and if sub-clinical infections with pig associated HEV strains occur in Sweden.

High prevalence of hepatitis E antibodies in pregnant Egyptian women

The epidemiology of hepatitis E virus (HEV), an enterically-transmitted cause of acute viral hepatitis (AVH), is not fully understood. During outbreaks on the Indian subcontinent and elsewhere, HEV causes severe AVH with mortality rates around 20% during pregnancy. In Egypt, where prevalence of HEV antibodies (anti-HEV) in rural communities is very high, severe HEV-caused AVH in pregnant women has not been reported. This study examined a cohort of 2,428 pregnant women in the Nile Delta to assess prevalence of, and risk factors for, anti-HEV and correlated these with history of liver disease. Anti-HEV prevalence was 84.3%. Several risk factors associated with anti-HEV included older age, many siblings, not using soap to wash produce and frequent contact with cats. History of jaundice and liver disease was rare and not increased in those having anti-HEV. Our results confirm Egypt's high HEV endemicity and show that almost all women of childbearing age in these communities had prior HEV exposures without a history of liver disease. Reasons for the lack of clinical hepatitis remain unclear but could be the result of early childhood HEV exposures, producing long-lasting immunity and/or modify subsequent responses to exposure. Alternatively, the predominant HEV strain(s) in Egypt are less virulent than those in South Asia.

Hepatitis E antibody seroconversion without disease in highly endemic rural Egyptian communities

Hepatitis E virus (HEV) is enterically transmitted and causes self-limiting acute viral hepatitis (AVH) primarily in less developed countries. A prospective cohort study to assess incidence of, and risk factors for, seroconversion to HEV (anti-HEV) was conducted in two Egyptian villages with a 67.7% anti-HEV prevalence. Nine hundred and nineteen villagers who were initially anti-HEV-negative were followed for 10.7 months. Thirty-four (3.7%) had strong anti-HEV serologic responses at follow-up giving an estimated anti-HEV incidence of 41.6/1,000 person-years. No significant associations were found between anti-HEV seroincidence and demographic and socioeconomic factors, source of water, household plumbing or sanitation, hand and vegetable washing, ownership of animals, jaundice and many other variables. None of the seroconverting subjects gave a history compatible with AVH during the interval. We hypothesize that both zoonotic and anthroponotic transmission of avirulent (possibly genotype-3) HEV is occurring extensively in these rural villages. An alternative explanation for the lack of morbidity among anti-HEV incident cases could be initial asymptomatic infections occur during early childhood with subsequent antibody titer boosting without illness upon re-exposure to the virus.

Seroprevalence of hepatitis E virus (HEV) antibody and the possible association with chronic liver disease: a case-control study in Albania

A case-control study involving 109 in-patients with chronic liver disease and 190 in-patients with no apparent liver disease was conducted to evaluate the seroprevalence of anti-HEV antibodies and the possible association with chronic liver disease. Among cases, the anti-HEV prevalence was 36.6% which increased significantly by age; among controls, the prevalence was 12.1% (P<0.05) and was similar among age groups <60 years. Among cases, aged >50 years (OR 4.0, 95% CI 1.4-11) and the presence of end stage liver disease (ESLD) (OR 4.3, 95% CI 1.4-12.8) were associated independently with anti-HEV positivity. The mean optical density, determined by anti-HEV immunoenzymatic test, was significantly higher among patients with ESLD, compared to the other patients. These results indicate that there is a high seroprevalence of anti-HEV in patients with chronic liver disease and a possible association between HEV infection and/or anti-HEV production and advanced stage chronic liver disease.

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

BackgroundThe 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.MethodsThis 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.ResultsThe 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.ConclusionWe 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 anti-HEV among swine, sheep and chickens

To investigate the prevalence of anti-HEV among swine, sheep and chickens. Totally 498 sera of swine, sheep and chickens collected from Xingjiang, Guangxi, Guangdong, Beijing and Hebei were detected for the anti-HEV by an enzyme linked immunoassay. The anti-HEV positive rate of swine was 67.53%(104/154), in pigs between 4-5 months of age the rate was 100.00%(9/9) from Xingjiang. The rate in pigs under 3 months of age from Guangxi was 36.00%(9/25) and in pigs older than six months of age was 71.67% (86/120), respectively. The 108 sera of sheep collected from Xingjiang were all negative. The positive rate of chickens was only 1.27% (3/236). The anti-HEV prevalence rates of chickens from Luoding, Shenzhen, Liuzhou, Beijing and Hebei were 4.00%, 1.49%, 1.49%, 0, 0 respectively. HEV infection does exist among swine and chickens. The anti-HEV prevalence of swine was the highest among domestic animals. The role of swine and chickens in transmission of HEV needs to be further studied.

Seroepidemiological markers of enterically transmitted viral hepatitis A and E in individuals living in a community located in the North Area of Rio de Janeiro, RJ, Brazil.

We investigated the seroprevalence of hepatitis A virus (HAV) and hepatitis E virus (HEV) infection in subjects living in the community of Manguinhos, Rio de Janeiro, Brazil, and assisted at the Health Unit of Escola Nacional de Saúde Pública, Fundação Oswaldo Cruz. After formal consent, individuals were submitted to an interview using a standardized questionnaire. Anti-HAV and anti-HEV antibodies were detected by ELISA. Statistical analysis was carried out using the Epi-Info 6.04b software, to investigate possible associations between serological markers and risk factors. Results were regarded as significant when p value < 0.05. Although a high prevalence of anti-HAV was observed (87%), almost 50% of subjects under the age of 10 were susceptible to HAV infection, an unexpected rate in endemic areas. This fact could be attributed to improvements in environmental sanitation, occurring in this area in the last years. The increasing proportion of susceptible people may result in outbreaks of HAV infection, since the virus still circulates in this area, as verified by the detection of anti-HAV IgM in some individuals. No statistical association was met between HAV infection and the risk factors here assessed. The anti-HEV IgG prevalence found in this population was 2.4%, consistent with the one found in non-endemic areas.

Prevalência da infecção pelos vírus das hepatites A e E em escolares de município da Amazônia Matogrossense

The prevalence of antibodies to hepatitis A anti-HAV total and E viruses anti-HEV IgG was assessed in 487 children ranging from 2 to 9 years old who were students of nurseries and public schools in a county of the Amazonian region, in Mato Grosso State, Brazil. The anti-HAV and anti-HEV prevalence were 86.4% (CI 95% 83 - 89.3) and 4.5% (CI95% 2.9 - 6.9), respectively. The anti-HAV prevalence was high in all ages, suggesting that this is an area of high endemicity for HAV infection. There was no association between the anti-HAV markers and gender, socioeconomic level, parental educational level, hygienic conditions, number or density of residents per room or schools in which they studied. Anti-HEV prevalence was low and similar to that found among adults in another Brazilian regions.

Prevalence of antibodies to hepatitis E virus in veterinarians working with swine and in normal blood donors in the United States and other countries.

Hepatitis E virus (HEV) is endemic in many developing and some industrialized countries. It has been hypothesized that animals may be the source of infection. The recent identification of swine HEV in U.S. pigs and the demonstration of its ability to infect across species have lent credence to this hypothesis. To assess the potential risk of zoonotic HEV infection, we tested a total of 468 veterinarians working with swine (including 389 U.S. swine veterinarians) and 400 normal U.S. blood donors for immunoglobulin G anti-HEV. Recombinant capsid antigens from a U.S. strain of swine HEV and from a human HEV strain (Sar-55) were each used in an enzyme-linked immunosorbent assay. The anti-HEV prevalence assayed with the swine HEV antigen showed 97% concordance with that obtained with the human HEV antigen (kappa = 92%). Among the 295 swine veterinarians tested from the eight U.S. states (Minnesota, Indiana, Nebraska, Iowa, Illinois, Missouri, North Carolina, and Alabama) from which normal blood donor samples were available, 26% were positive with Sar-55 antigen and 23% were positive with swine HEV antigen. In contrast, 18% of the blood donors from the same eight U.S. states were positive with Sar-55 antigen and 17% were positive with swine HEV antigen. Swine veterinarians in the eight states were 1.51 times more likely when tested with swine HEV antigen (95% confidence interval, 1.03 to 2.20) and 1.46 times more likely when tested with Sar-55 antigen (95% confidence interval, 0.99 to 2.17) to be anti-HEV positive than normal blood donors. We did not find a difference in anti-HEV prevalence between veterinarians who reported having had a needle stick or cut and those who had not or between those who spent more time (> or = 80% of the time) and those who spent less time (< or = 20% of the time) working with pigs. Similarly, we did not find a difference in anti-HEV prevalence according to four job categories (academic, practicing, student, and industry veterinarians). There was a difference in anti-HEV prevalence in both swine veterinarians and blood donors among the eight selected states, with subjects from Minnesota six times more likely to be anti-HEV positive than those from Alabama. Age was not a factor in the observed differences from state to state. Anti-HEV prevalence in swine veterinarians and normal blood donors was age specific and paralleled increasing age. The results suggest that swine veterinarians may be at somewhat higher risk of HEV infection than are normal blood donors.

High prevalence of hepatitis E antibodies among Danish prisoners and drug users.

Injecting drug users and prisoners have high prevalences of antibodies to hepatitis A-C. The aim of this study was to determine the prevalence of antibodies to hepatitis E virus (anti-HEV) in two Danish high-risk populations and correlate anti-HEV with risk factors for transmission. Three hundred thirty male prisoners and 137 patients at a drug treatment center were tested for anti-HEV with an in-house enzyme-linked immunoassay (EIA) utilizing antigens derived from open reading frame 2 (ORF2). This was compared with a commercial test with antigens derived from ORF2 and ORF3 (Abbott HEV EIA). In addition the samples were tested for antibodies against hepatitis A-C viruses, human immunodeficiency virus (HIV) 1 and 2, human T lymphotropic virus (HTLV) I and II and herpes simplex virus type 2 (HSV2). The participants were interviewed about risk factors for transmission. The anti-HEV prevalence was 16.9% (95% CI 14-21) for the in-house assay compared to 4.1% (95% CI 2.5-6.3) with the commercial assay. The correlation between the two assays was low (87% overall agreement; kappa value 0.32). One sample was strongly anti-HEV IgM positive, suggesting recent HEV infection inside Denmark. The presence of anti-HEV was associated significantly with anti-HAV among prisoners and increased with age in both groups. In contrast, associations were not found with injecting drug use or sexual risk factors. With the commercial assay an increased prevalence of anti-HEV was found among participants who had spent more than 5 years outside Northern Europe. In conclusion, anti-HEV was highly prevalent among Danish prisoners and drug users but not related to risk factors for blood-borne or sexual transmission.

Hepatitis E virus infection in selected Brazilian populations.

A retrospective study on the prevalence of hepatitis E virus (HEV) infection was conducted in selected populations in Rio de Janeiro, Brazil. A total of 1,115 subjects were tested including 146 patients with acute Non-A Non-B Non-C (NANBNC) viral hepatitis, 65 hemodialysis patients, 93 blood donors, 102 intravenous drug users (IVDUs), 304 pregnant women, 145 individuals living in the rural area and 260 individuals living in the urban area. In order to characterize a favorable epidemiological set for enterically transmitted infection in the studied populations we also evaluated the prevalence of anti-HAV IgG (hepatitis A virus) antibodies. Specific antibodies to HEV (anti-HEV IgG) were detected by a commercial EIA and specific antibodies to HAV (anti-HAV IgG) were detected using a competitive "in house" EIA. We found a high prevalence of anti-HAV IgG in these populations, that could indicate some risk for infections transmitted via the fecal-oral route. The anti-HEV IgG prevalence among the different groups were: 2.1% in patients with acute NANBNC viral hepatitis, 6.2% in hemodialysis patients, 4.3% in blood donors, 11.8% in IVDUs, 1% in pregnant women, and 2.1% in individuals form the rural area. Among individuals living in the urban area we did not find a single positive serum sample. Our results demonstrated the presence of anti-HEV IgG in almost all studied populations; however, further studies are necessary to establish the real situation of HEV epidemiology in Rio de Janeiro, Brazil.

Prevalence of Antibody to Hepatitis E Virus among Rodents in the United States

The recent identification of antibody to hepatitis E virus (HEV) in pigs, sheep, and cattle and characterization of an HEV isolated from domestic pigs suggest animal reservoirs for this virus. To investigate whether rodents might be a natural reservoir of HEV, the prevalence of anti-HEV was determined among a variety of species throughout the United States. Serum samples were obtained from 806 rodents of 26 species in 15 genera. Anti-HEV prevalence was assessed by 2 EIAs (mosaic protein- and 55-kDa protein-based), which gave concordant results. The highest prevalence of antibody was found in the genus Rattus (59.7%; 166/278). Overall, rodents from urban habitats had a significantly higher prevalence of anti-HEV than did animals captured from rural areas. A high prevalence of anti-HEV was found in animals captured on mainland versus barrier islands. The results from this study provide convincing evidence of widespread HEV or HEV-like infection in rodents of the United States.

Role of hepatitis E and other hepatotropic virus in aetiology of sporadic acute viral hepatitis: a hospital based study from urban Delhi.

Major hepatotropic virus continues to be an important cause of acute viral hepatitis (AVH) in developing countries like India. While epidemics of AVH have been well studied few serious sporadic cases from developing countries have been reviewed. We studied prospectively 75 cases of sporadic AVH who reported to our hospital and were evaluated for the presence of various hepatotropic viruses. The seroprevalence of IgG anti-HEV antibodies was studied in the general population as a control. We found 53.3% (40/75) of sporadic AVH cases were due to hepatitis E virus while 11% (8/75) were due to hepatitis B virus. Hepatitis C virus was responsible for 8% (6/75) of the sporadic AVH cases and hepatitis A was found in 5% (4/75) of the cases. No causative agent was found in 23% (17/75) of the sporadic AVH cases. The sporadic AVH cases due to HEV were not clinically or biochemically not different from AVH due to other viruses. We found a high prevalence of IgG anti-HEV in 35.6% (178/500) among the general population of urban Delhi. The study suggested that hepatitis E was the most common cause of sporadic AVH in urban Delhi. High seroprevalence of IgG anti-HEV antibodies in the general population and amongst the sporadic AVH cases suggests that it is unlikely to be protective antibody. IgM anti-HEV positive serology is considered diagnostic of acute hepatitis E infection in India, where hepatitis E is endemic.

Hepatitis E virus infection prevalence among selected populations in Iowa.

HEV causes an enteric infectious disease endemic in developing areas with hot climate. A case of endogenous HEV infection has been reported in the US. Recently, HEV-like virus was isolated from swine in Iowa. Swine production is a major industry in Iowa with the potential for human exposure to swine in and around industrial and family farm operations. The study objective was to determine whether individuals in Iowa are exposed to HEV. Anti-HEV antibody prevalence in four selected Iowa populations was determined. Sera were collected from 204 patients with non-A, non-B, non-C hepatitis (non-A-C); 87 staff members of the Department of Natural Resources (DRN); 332 volunteer blood donors in 1989; and 111 volunteer blood donors in 1998. All sera were tested for anti-human HEV IgM and IgG by ELISA with confirmation of positivity by a peptide neutralization test. Both the patients with non-A, non-B, non-C hepatitis (4.9%) and the healthy field workers from the Iowa DNR (5.7%) showed significantly higher prevalence of anti-HEV IgG antibodies compared to normal blood donor sera collected in 1998 (P < 0.05). Human HEV or a HEV-like agent circulates in the Iowa geographical area. At-risk human populations with occupational exposure to wild animals and environmental sources of domestic animal wastes or with unexplained hepatitis have increased seroprevalence of HEV antibodies.