Evidence that rodents are a reservoir of hepatitis E virus for humans in Nepal

Research on a rat model of genotype IV swine hepatitis E virus

BACKGROUND

Hepatitis E virus (HEV) is an important zoonotic pathogen, Genotypes 3 and 4 are the main zoonotic genotype. Due to the lack of mature and effective culture cell lines, researches on genotype IV swine HEV (SHEV-4) infection and pathogenic mechanism have been carried out in pigs, gerbils and non-human primate models.

OBJECTIVES

The aim of this study was to establish a rat infection model by intra-peritoneal infection with SHEV-4, which provided a new research idea and scientific basis for further revealing the mechanism of HEV infection and preventing HEV infection.

METHODS

SHEV-4 virus was administered intra-peritoneally to 6- to 8-week-old mice to observe the serological changes and virus release.

RESULTS

According to the results of the rat serum HEV IgG, ALT and AST levels, swine HEV, minus-strand HEV RNA can infect Sprague-Dawley rats across species, and there are no obvious clinical symptoms after infection. HEV RNA was detected in most tissues and organs after infection, but the viral load was low. The liver had pathological changes of chronic hepatitis.

CONCLUSIONS

We found that the rat model of porcine HEV infection is a small animal model suitable for the study of HEV infection.

Rodent-Related Zoonotic Pathogens at the Human-Animal-Environment Interface in Qatar: A Systematic Review and Meta-Analysis

Rodents are one of the most diversified terrestrial mammals, and they perform several beneficial activities in nature. These animals are also important as carriers of many pathogens with public health importance. The current systematic review was conducted to formulate a true depiction of rodent-related zoonoses in Qatar. Following systematic searches on PubMed, Scopus, Science Direct, and Web of Science and a screening process, a total of 94 published articles were selected and studied. The studied articles reported 23 rodent-related zoonotic pathogens that include nine bacterial, eleven parasitic, and three viral pathogens, from which the frequently reported pathogens were Mycobacterium tuberculosis (32 reports), Escherichia coli (23), and Salmonella spp. (16). The possible pathway of entry of the rodent-borne pathogens can be the land port, seaports, and airport of Qatar through carrier humans and animals, contaminated food, and agricultural products. The pathogens can be conserved internally by rodents, pets, and livestock; by agricultural production systems; and by food marketing chains. The overall estimated pooled prevalence of the pathogens among the human population was 4.27% (95%CI: 4.03–4.51%; p < 0.001) with significant heterogeneity (I² = 99.50%). The top three highest prevalent pathogens were M.tuberculosis (30.90%; 22.75–39.04%; p < 0.001; I² = 99.70%) followed by Toxoplasma gondii (21.93%; 6.23–37.61%; p < 0.001; I² = 99.30%) and hepatitis E virus (18.29%; 11.72–24.86%; p < 0.001; I² = 96.70%). However, there is a knowledge gap about the listed pathogens regarding the occurrence, transmission pathways, and rodent role in transmission dynamics at the human–animal–environment interface in Qatar. Further studies are required to explore the role of rodents in spreading zoonotic pathogens through the One Health framework, consisting of zoologists, ecologists, microbiologists, entomologists, veterinarians, and public health experts in this country.

The Role of Peridomestic Rodents as Reservoirs for Zoonotic Foodborne Pathogens

Although rodents are well-known reservoirs and vectors for a number of zoonoses, the functional role that peridomestic rodents serve in the amplification and transmission of foodborne pathogens is likely underappreciated. Clear links have been identified between commensal rodents and outbreaks of foodborne pathogens throughout Europe and Asia; however, comparatively little research has been devoted to studying this relationship in the United States. In particular, regional studies focused on specific rodent species and their foodborne pathogen reservoir status across the diverse agricultural landscapes of the United States are lacking. We posit that both native and invasive species of rodents associated with food-production pipelines are likely sources of seasonal outbreaks of foodborne pathogens throughout the United States. In this study, we review the evidence that identifies peridomestic rodents as reservoirs for foodborne pathogens, and we call for novel research focused on the metagenomic communities residing at the rodent-agriculture interface. Such data will likely result in the identification of new reservoirs for foodborne pathogens and species-specific demographic traits that might underlie seasonal enteric disease outbreaks. Moreover, we anticipate that a One Health metagenomic research approach will result in the discovery of new strains of zoonotic pathogens circulating in peridomestic rodents. Data resulting from such research efforts would directly inform and improve upon biosecurity efforts, ultimately serving to protect our food supply.

First report of hepatitis E virus viremia in healthy blood donors from Nepal

The aim of this study was to detect the prevalence of hepatitis E virus (HEV) in healthy blood donors so as to decipher the maintenance of (HEV) reservoir if any. Five hundred and eighty-one blood samples along with clinical information were collected from central blood bank, Kathmandu between February and March 2014. Samples were tested for hepatitis B virus surface antigen, anti-hepatitis C virus antibodies, anti-hepatitis A virus IgM, HEV antigen, HEV viral load and anti-HEV antibodies (IgM and IgG) by ELISA. Only those samples positive with anti-HEV IgM were tested for HEV RNA by reverse transcriptase nested PCR. Age adjusted prevalence of IgM anti HEV and IgG anti HEV were 3.6 and 8.3 % respectively. No significant difference in Median ALT levels was noted between HEV RNA positive and negative subjects. Sequence analysis of HEV shows all genotype belongs to genotype 1a. Phylogenetic analysis shows the virus has homology of 95 % with strain from India and Nepal outbreak of April 2014. This study sheds light on how inter epidemic reservoirs can be maintained in healthy population with asymptomatic cases. This raises an important question regarding nature of HEV as well as its tendency to circulate in blind sight and also cause periodic outbreaks in endemic setting like Kathmandu.

Hepatitis E: latest developments in knowledge

Hepatitis E, caused by Hepatitis E virus (HEV), is a highly prevalent disease in developing countries. In developed nations, autochthonous HEV infections seem to be an emergent disease. Its clinical manifestations and epidemiology are well known for endemic countries. It has been confirmed that hepatitis E is a zoonosis and that parenteral transmission can also occur. The molecular mechanisms of HEV replication are not fully understood, mostly because there are no efficient cell culture systems. HEV can cause chronic hepatitis in organ transplant recipients and immunocompetent patients. Cases with fulminant hepatitis and other extrahepatic manifestations have also been reported. The diagnosis is based on serological studies and detection of HEV RNA in blood and feces. Treatment with ribavirin and/or pegylated-IFN-α have proven to be successful in some cases. The recently approved/marketed vaccine is a good option in order to prevent this infection.

Molecular Investigation on the Presence of Hepatitis E Virus (HEV) in Wild Game in North-Western Italy

Meat products from HEV-infected reservoir animal species are capable of transmitting HEV to humans and represent a public health concern. Human HEV cases have been linked to the consumption of raw or undercooked pig liver sausages, pork, and game meats, such as wild boars and deer worldwide. Direct exposure to swine or wild game species might also represent a source of HEV transmission especially for veterinarians, hunters, or butchers. A limited amount of data is available on HEV prevalence in wild boars in Italy and no data are available for other wild game species intended for human consumption. In this study, the circulation of HEV in four different animal species hunted in north-western Italy was evaluated to gain insight into the infection levels and the genetic diversity of the virus in such animal populations. Liver samples of 372 wild boars, 30 roe deer, 47 European hares and 38 coypus were analyzed for HEV RNA by real-time RT-PCR; positive samples were then sequenced and submitted to phylogenetic analysis. HEV RNA was detected in the livers of 7/372 (1.9%) wild boars tested, while no sample was positive for roe deer, European hare, and coypu. Phylogenetic analysis showed that wild boar HEV sequences belonged to HEV subtypes 3e, 3c, and 3f. Our results indicate that HEV is circulating only in wild boar among the considered game species in north-western Italy and suggest a potential zoonotic risk related to handling and/or consumption of raw or undercooked meat and products made of the liver from this species.

Hepatitis E: A disease of reemerging importance

Hepatitis E virus (HEV) is the most common cause of acute viral hepatitis worldwide. Originally considered to be restricted to humans, it is now clear that HEV and HEV-like viruses have several animal reservoirs with complex ecology and genetic diversity, as exemplified by the recent discovery of HEV in dromedaries, a previously underestimated reservoir of zoonotic viruses prior to the emergence of Middle East Respiratory Syndrome coronavirus. Zoonotic foodborne transmission from pigs and feral animals such as wild boar is of increasing importance in the rapidly industrializing countries of the Asia Pacific region. Such zoonotic hepatitis E infection has particular relevance to the increasing population living with immunosuppression, due to the risk of chronic hepatitis E in these patients. Fortunately, major strides have been made recently in the management of chronic hepatitis E patients. Furthermore, an effective vaccine is also available that promises better control of hepatitis E burden in the near future. This review highlights these major recent developments in the epidemiology, treatment, and prevention of hepatitis E.

Rare detection of occult hepatitis B virus infection in children of mothers with positive hepatitis B surface antigen

The prevalence of occult Hepatitis B virus (HBV) infection in children was considerably varied from 0.1–64% in different reports. In this study we aimed to investigate the prevalence of occult HBV infection among the children born to mothers with positive hepatitis B surface antigen (HBsAg) in Jiangsu, China. Serum samples were collected from 210 children of 207 mothers with positive HBsAg. HBV serological markers were detected by ELISA and HBV DNA was detected by nested PCR. Homology comparison of HBV sequences recovered from the child and mother was used to define the infection. Three children (1.43%) were positive for HBsAg, in whom the HBV pre S and S gene sequence in each child was identical to that in her mother. Of the 207 HBsAg-negative children, nine displayed HBV DNA positive by two nested PCR assays using primers derived from S and C genes. However, the sequence alignment showed that the sequences in each child were considerably different from those in his/her mother. Therefore, the sequences amplified from the children were very likely resultant from the cross-contaminations. Furthermore, the nine children with ‘positive HBV DNA’ were all negative for anti-HBc, and one had anti-HBs 3.42 mIU/ml and eight others had anti-HBs from 72 to >1000 mIU/ml, indicating that the nine children were less likely infected with HBV. Therefore, none of the 207 HBsAg-negative children of HBV-infected mothers was found to have occult HBV infection. We conclude that the prevalence of occult HBV infection in vaccinated children born to HBsAg positive mothers should be extremely low. We recommend that homology comparison of sequences recovered from the child and mother be used to define the occult HBV infection in children born to HBV infected mothers.

Susceptibility of laboratory rats against genotypes 1, 3, 4, and rat hepatitis E viruses

To determine whether or not rats are susceptible to hepatitis E virus (HEV) infection, each of group containing three laboratory rats (Wistar) were experimentally inoculated with genotypes 1, 3, 4 and rat HEV by intravenous injection. Serum and stool samples were collected and used to detect HEV RNA and anti-HEV antibodies by RT-PCR and ELISA, respectively. The virus infection was monitored up to 3 months after inoculation. None of the serum or stool samples collected from the rats inoculated with G1, G3, or G4 HEV indicated positive sign for virus replication. Although no alteration was observed in ALT level, rat HEV RNA was detected in stools from both of the rats inoculated with rat HEV, and both rats were positive for anti-rat HEV IgG and IgM from 3 weeks after inoculation. These results demonstrated that rats are susceptible to rat HEV but not to G1, G3, and G4 HEV. We also confirm that the nude rats were useful for obtaining a large amount of rat HEV and that the rat HEV was transmitted by the fecal-oral route.

Hepatitis E virus genotype 3 in wild rats, United States

The role of rodents in the epidemiology of zoonotic hepatitis E virus (HEV) infection has been a subject of considerable debate. Seroprevalence studies suggest widespread HEV infection in commensal Rattus spp. rats, but experimental transmission has been largely unsuccessful and recovery of zoonotic genotype 3 HEV RNA from wild Rattus spp. rats has never been confirmed. We surveyed R. rattus and R. norvegicus rats from across the United States and several international populations by using a hemi-nested reverse transcription PCR approach. We isolated HEV RNA in liver tissues from 35 of 446 rats examined. All but 1 of these isolates was relegated to the zoonotic HEV genotype 3, and the remaining sequence represented the recently discovered rat genotype from the United States and Germany. HEV-positive rats were detected in urban and remote localities. Genetic analyses suggest all HEV genotype 3 isolates obtained from wild Rattus spp. rats were closely related.

Hepatitis E virus in rats, Los Angeles, California, USA

This virus is unlikely to be a zoonotic threat.

The role of rats in human hepatitis E virus (HEV) infections remains controversial. A genetically distinct HEV was recently isolated from rats in Germany, and its genome was sequenced. We have isolated a genetically similar HEV from urban rats in Los Angeles, California, USA, and characterized its ability to infect laboratory rats and nonhuman primates. Two strains of HEV were isolated from serum samples of 134 wild rats that had a seroprevalence of antibodies against HEV of ≈80%. Virus was transmissible to seronegative Sprague-Dawley rats, but transmission was spotty and magnitude and duration of infection were not robust. Viremia was higher in nude rats. Serologic analysis and reverse transcription PCR were comparably sensitive in detecting infection. The sequence of the Los Angeles virus was virtually identical to that of isolates from Germany. Rat HEV was not transmissible to rhesus monkeys, suggesting that it is not a source of human infection.

Analysing complete genome sequence of swine hepatitis E virus (HEV), strain CHN-XJ-SW13 isolated from Xinjiang, China: putative host range, and disease severity determinants in HEV

Hepatitis E is a worldwide public health problem, particular in areas where hygiene conditions are poor. Hepatitis E virus (HEV) has at least four genotypes: genotypes 1 and 2 exclusively infect human; while genotypes 3 and 4, are considered to be a zoonotic agent, infecting both humans and animals. This study was aimed at determining why genotype 3 and 4 HEV strains isolated from swine are able to cross species borders, whereas genotype1 and 2 strains isolated from humans are not. The full length genome of the swine HEV isolate CHN-XJ-SW13 was amplified as overlapping fragments using reverse-transcription-nested polymerase chain reaction (RT-nPCR) and rapid amplification of cDNA ends (RACE). The sequence of CHN-XJ-SW13 was compared with those of 90 HEV strains covering genotype 1-4 retrieved from GenBank. Possible regions of the viral genome, specifying the host range of HEV or associated with the severity of hepatitis E disease, were then screened for with the aid of the ALIGNX sequences alignment software package. The CHN-XJ-SW13 swine HEV isolate was determined to be a novel subtype of genotype 4, whose sequence provided several valuable clues for tracing the sources of human HEV infection. 25 specific nucleotide positions were identified to possibly being involved specifying the host range of HEV or determining the severity of hepatitis E disease.

[Seroprevalence and risk factors of hepatitis E among pregnant women in central Tunisia]

OBJECTIVES

The study was conducted to investigate the prevalence and risk factors for hepatitis E virus (HEV) infection in Tunisian pregnant women.

METHODS

A total of 404 pregnant women were enrolled. Data were collected through a standard questionnaire which covered sociodemographic characteristics and risk factors. Blood samples were collected and were tested for HEV IgM and IgG antibodies, IgG against hepatitis A (anti-HAV IgG), hepatitis B virus surface antigen (HBsAg) and hepatitis C virus antibody (anti-HCV). Risk factors were analyzed using univariate and multivariate logistic regression models.

RESULTS

Prevalence of anti-HEV IgG, anti-HEV IgM, anti-HAV IgG, HBs Ag and anti-HCV was 12.1 %, 0 %, 97 %, 3 % and 0,5 %, respectively. In multivariate analysis age (>30 years) and the number of persons per room (>2) in the house were independent factors predicting HEV infection. History of agricultural work, kind of water, sewage treatment, use detergent to wash vegetables, contact with animals and parenteral risk factors were not correlated with the presence of anti-HEV IgG.

CONCLUSION

The important seropositive rate among pregnant women is compatible with endemicity of HEV in Tunisia. Hepatitis E should be considered in the diagnosis of acute hepatitis during pregnancy. Our result suggests that infection occurs sporadically by person-to-person transmission route but further investigations are needed to determine the natural reservoir of infection.

Experimental infection of Mongolian gerbils by a genotype 4 strain of swine hepatitis E virus

An ideal animal model for hepatitis E virus (HEV) research is still unavailable. To assess the possibility of using Mongolian gerbils as animal model, 28 gerbils were randomly assigned into two groups, 14 for each group. Gerbils in Group 1 were inoculated with a genotype 4 HEV recovered from swine via the intraperitoneal route. Group 2 was used as a negative control and inoculated with normal suspension of swine liver. Sera and feces samples were collected once a week for 7 weeks. Two gerbils from both groups were necropsied weekly, pathological changes were recorded and tissue samples collected for further investigation. Distribution of the virus antigens was determined by immunohistochemical staining. Nested RT-PCR and a commercial ELISA kit were used to confirm the infection. Research results demonstrated that Mongolian gerbils in Group 1 were successfully infected with HEV. Viremia and fecal virus shedding lasted nearly 4 weeks, while the virus could be detected constantly in the liver, and occasionally in the kidneys and spleen as well as the small intestine. Histopathological changes in the liver were present with slight, multifocal, lymphohistiocytic infiltrates in the portal tracts or distributed irregularly throughout the liver. HEV antigens could be detected in the liver and intestine, and were mainly distributed in the nuclei. The results indicate that Mongolian gerbils could be used as an ideal animal model for the study of HEV.

Hepatitis E: an emerging infection in developed countries

Hepatitis E is endemic in many developing countries where it causes substantial morbidity. In industrialised countries, it is considered rare, and largely confined to travellers returning from endemic areas. However, there is now a growing body of evidence that challenges this notion. Autochthonous hepatitis E in developed countries is far more common than previously recognised, and might be more common than hepatitis A. Hepatitis E has a predilection for older men in whom it causes substantial morbidity and mortality. The disease has a poor prognosis in the context of pre-existing chronic liver disease, and is frequently misdiagnosed as drug-induced liver injury. The source and route of infection remain uncertain, but it might be a porcine zoonosis. Patients with unexplained hepatitis should be tested for hepatitis E, whatever their age or travel history.

Hepatitis E: a complex and global disease

Thirty years after its discovery, the hepatitis E virus (HEV) continues to represent a major public health problem in developing countries. In developed countries, it has emerged as a significant cause of non-travel-associated acute hepatitis. HEV infects a wide range of mammalian species and a key reservoir worldwide appears to be swine. Genomic sequence similarity between some human HEV genotypes and swine HEV strains has been identified and we know that humans can acquire HEV infection from animals. Although for the most part the clinical course of HEV infection is asymptomatic or mild, significant risk of serious disease exists in pregnant women and those with chronic liver disease. In addition, there are data on the threat of chronic infections in immunocompromised patients. Beyond management of exposure by public health measures, recent data support that active immunisation can prevent hepatitis E, highlighting the need for vaccination programmes. Here we review the current knowledge on HEV, its epidemiology, and the management and prevention of human disease.

Hepatitis E: an emerging awareness of an old disease

Although hepatitis E was recognized as a new disease in 1980, the virus was first visualized in 1983 and its genome was cloned and characterized in 1991, the disease is probably ancient but not recognized until modern times. Hepatitis E is the most important or the second most important cause of acute clinical hepatitis in adults throughout Asia, the Middle East and Africa. In contrast, hepatitis E is rare in industrialized countries, but antibody (anti-HEV) is found worldwide. HEV is a small round RNA-containing virus that is the only member of the genus Hepevirus in the family Hepeviridae. Although similar to hepatitis A virus in appearance, there are significant differences between the two viruses. Hepatitis E is principally the result of a water-borne infection in developing countries and is thought to be spread zoonotically (principally from swine) in industrialized countries. Because diagnostic tests vary greatly in specificity, sensitivity and availability, hepatitis E is probably underdiagnosed. At present, control depends upon improved hygiene; a highly efficacious vaccine has been developed and tested, but it is not presently available.

[Hepatitis E virus: zoonotic implications]

The Hepatitis E virus (HEV) is transmitted primarily by the feco-oral route throughout contaminated water and/or food, and is one of the main causes of acute hepatitis worldwide. Hepatitis E shows a high mobility but a low mortality rate, except in pregnant women, where it can be as high as 30%. HEV causes sporadic cases and epidemic outbreaks, mainly in Africa, Asia and Central America. In Europe, there is an increase in the number of reported autochthonous cases no related with travel to endemic areas. In addition, HEV also infects animals, including pigs, and its zoonotic potential has been recently demonstrated. In fact, porcine and human strains of the same area are genetically more closely related to each other than to strains of the same species but a different geographical region, and there are data suggesting that people in close contact with pigs presents a higher prevalence of specific anti-HEV antibodies. All together, these data have drove to an increase interest in determining the incidence of the disease in animals, its possible zoonotic risk, and its implications for human health. In the present article we revised the current knowledge about HEV, with special emphasis in the possible consequences of its zoonotic potential.

Identification of genotype 1 hepatitis E virus in samples from swine in Cambodia

Hepatitis E virus (HEV) is a major enterically transmitted pathogen in many developing countries, where it causes outbreaks and sporadic cases of acute hepatitis. A study conducted with pigs from several livestock farms in Cambodia identified one swine genotype 1 HEV isolate as being associated with prevalent swine genotype 3 HEV.

Phylogenetic analysis of global hepatitis E virus sequences: genetic diversity, subtypes and zoonosis

Nucleotide sequences from a total of 421 HEV isolates were retrieved from Genbank and analysed. Phylogenetically, HEV was classified into four major genotypes. Genotype 1 was more conserved and classified into five subtypes. The number of genotype 2 sequences was limited but can be classified into two subtypes. Genotypes 3 and 4 were extremely diverse and can be subdivided into ten and seven subtypes. Geographically, genotype 1 was isolated from tropical and several subtropical countries in Asia and Africa, and genotype 2 was from Mexico, Nigeria, and Chad; whereas genotype 3 was identified almost worldwide including Asia, Europe, Oceania, North and South America. In contrast, genotype 4 was found exclusively in Asia. It is speculated that genotype 3 originated in the western hemisphere and was imported to several Asian countries such as Japan, Korea and Taiwan, while genotype 4 has been indigenous and likely restricted to Asia. Genotypes 3 and 4 were not only identified in swine but also in wild animals such as boar and a deer. Furthermore, in most areas where genotypes 3 and 4 were characterised, sequences from both humans and animals were highly conserved, indicating they originated from the same infectious sources. Based upon nucleotide differences from five phylogenies, it is proposed that five, two, ten and seven subtypes for HEV genotypes 1, 2, 3 and 4 be designated alphabetised subtypes. Accordingly, a total of 24 subtypes (1a, 1b, 1c, 1d, 1e, 2a, 2b, 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, 3j, 4a, 4b, 4c, 4d, 4e, 4f and 4g) were given.

Infectious swine hepatitis E virus is present in pig manure storage facilities on United States farms, but evidence of water contamination is lacking

Fresh feces, manure slurry (from earthen lagoons and/or concrete pits), and drinking and surface water samples were collected from 28 pig farms in the Midwestern United States. All samples were tested for hepatitis E virus (HEV) RNA by reverse transcription-PCR. Seven of 28 farms had fecal samples that contained HEV. Of 22 farms where pit samples were accessible, 15 contained HEV, and of 8 farms that had lagoons, 3 contained HEV. The highest virus titers were 10 and 10(3) genome equivalents per 60 ml of manure slurry in lagoon and pit samples, respectively. None of the water samples tested HEV positive. To determine the infectivity of the HEV found in the positive farm 19 lagoon (designated L19) or farm 12 pit (designated P12) samples, pigs were inoculated either intravenously (n = 3) or orally (n = 3) with the L19 or P12 manure slurry. Four pigs inoculated intravenously with prototype swine HEV served as positive controls. All positive-control pigs shed HEV in feces and 3 of 4 developed anti-HEV antibodies. Two pigs in the intravenously inoculated P12 group shed HEV in feces, and one of the pigs seroconverted to anti-HEV antibodies. None of the pigs in the negative-control, L19 oral, L19 intravenous, or P12 oral group shed HEV in feces. The findings indicate that HEV found in pig manure slurry was infectious when inoculated intravenously. Pit manure slurry is a potential source of HEV infection and for contamination of the environment. Contamination of drinking or surface water with HEV was not found on or near the pig farms.

Prevalence of hepatitis E virus infection in Japanese children

BACKGROUND

Recently, sporadic cases of acute hepatitis and fulminant hepatitis caused by hepatitis E virus (HEV) have been reported in Japan. However, few reports have addressed the issue of HEV infection during childhood.

METHODS

This study included 5 patients with fulminant hepatitis, 30 patients with acute hepatitis, and 309 patients without history of hepatic dysfunction or hepatitis in childhood as control. RNA was extracted from each serum sample, and HEV specific reverse-transcriptase polymerase chain reaction was performed. Anti-HEV immunoglobulin (Ig)M and IgG were measured by enzyme-linked immunoadsorbent assay.

RESULTS

HEV RNA, anti-HEV IgM, and anti-HEV IgG were not detected in the sera of any of the five patients with fulminant hepatitis. In the 30 patients with acute hepatitis, only one (3.3%) was positive for anti-HEV IgG, and all were negative for anti-HEV IgM and HEV RNA. Of the 309 control patients, 8 (2.6%) were positive for anti-HEV IgG, and 2 (0.6%) were positive for anti-HEV IgM, respectively.

CONCLUSION

The result of patients with fulminant hepatitis suggests that HEV is an unlikely cause of fulminant hepatitis in children. However, the detection rate of anti-HEV IgG shows that a history of HEV infection is not so rare among children in Japan.

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.

Hepatitis E viruses in humans and animals

Hepatitis E virus (HEV) is an emerging pathogen belonging to a newly recognized family of RNA viruses (Hepeviridae). HEV is an important enterically transmitted human pathogen with a worldwide distribution. It can cause sporadic cases as well as large epidemics of acute hepatitis. Epidemics are primarily waterborne in areas where water supplies are contaminated with HEV of human origin. There is increasing evidence, however, that many animal species are infected with an antigenically similar virus. A recently isolated swine virus is the best candidate for causing a zoonotic form of hepatitis E. The virus is serologically cross-reactive with human HEV and genetically very similar, and the human and swine strains seem to be cross-infective. Very recent evidence has also shown that swine HEV, and possibly a deer strain of HEV, can be transmitted to humans by consumption of contaminated meat. In this review, we discuss the prevalence, pathogenicity, diagnosis and control of human HEV, swine HEV, the related avian HEV and HEV in other hosts and potential reservoirs.

[Recent topics on hepatitis E virus: emerging, zoonotic, and animal-to-human transmission in Japan]

Hepatitis E is undoubtedly a zoonosis. Recent observations suggest that the zoonotic food-borne mode of transmission has played an important role in the spread of hepatitis E virus (HEV) among Japanese people (who in general likes eating everything uncooked or undercooked: Sushi, Sashimi, Tataki, Namagimo, Shabu-shabu, etc). Moreover, the situation seems to be worsening. Wild boar (and deer also) has recently been increasing in its number, becoming a more potent HEV reservoir to humans than before. Pork, replacing beef in people's recent fear of BSE, is being consumed increasingly, particularly in Hokkaido. It may be Japanese people that an effective HEV vaccine is most longed for by.

Possible risk factors for the transmission of hepatitis E virus and for the severe form of hepatitis E acquired locally in Hokkaido, Japan

Hepatitis E in industrialized countries has not been well studied. To define the possible risk factors for transmission of hepatitis E virus (HEV) and for the severe form of hepatitis E in Japan, we investigated the clinical and virological characteristics of hepatitis E in 32 patients who contracted the mild (n=23) or severe form (n=9) of domestically acquired hepatitis E between 1996 and 2004 in Hokkaido, where hepatitis E is most prevalent in Japan. Nine patients with the severe form of hepatitis E included two patients with fulminant hepatitis E and seven patients who were diagnosed with severe acute hepatitis in which hepatic encephalopathy did not appear during the course of the illness despite low plasma prothrombin activity (<or=40%) and/or increased total bilirubin level (>or=20 mg/dl). At least 25 patients (78%) had consumed uncooked or undercooked pig liver and/or intestine 1-2 months before the onset of hepatitis E. When compared with the seven patients with HEV genotype 3, the 25 patients with HEV genotype 4 had a higher peak alanine aminotransferase (ALT) level (P=0.0338) and a lower level of lowest prothrombin activity (P=0.0340). The severe form of hepatitis E was associated with the presence of an underlying disease (56% [5/9] vs. 17% [4/23], P=0.0454). The study suggests that zoonotic food-borne transmission of HEV plays an important role in the occurrence of hepatitis E in Hokkaido, Japan, and that the HEV genotype and the presence of an underlying disease influence the severity of hepatitis E.

Hepatitis E in the south west of France in individuals who have never visited an endemic area

A total of 431 consecutive patients from the Midi Pyrenees area with acute hepatitis with unknown etiology in 2001-2002 were tested for the presence of immunoglobulin G-class (IgG) anti-hepatitis E virus (HEV) antibodies. Forty-six (10.7%) had anti-HEV IgG, and the results were questionable for a further 17 (3.9%). Real time PCR based on TaqMan detection was used to identify HEV genome fragments in the serum of patients with positive or questionable anti-HEV serology. HEV RNA was found in 25.4% of cases. All amplification products were sequenced and analyzed. Phylogenetic analysis revealed that all the strains were genotype 3. In conclusion, virological and epidemiological data indicate that genotype 3 viruses are circulating in the south west part of France (Midi-Pyrenees) in patients with acute hepatitis and who have not visited recently areas in which HEV is endemic.

Transfusion-transmitted hepatitis E caused by apparently indigenous hepatitis E virus strain in Hokkaido, Japan

BACKGROUND

In industrialized countries, sporadic cases of hepatitis E have been reported in individuals who have never been in an endemic area. Hepatitis E virus (HEV) infection commonly occurs via the fecal-oral route but a potential risk of transfusion transmission route has been suggested.

STUDY DESIGN AND METHODS

A 67-year-old Japanese male patient who had never been abroad received a transfusion of blood from 23 voluntary donors and developed acute hepatitis with unknown etiology after transfusion. His blood samples were tested for viral markers of hepatitis viruses.

RESULTS

HAV, HBV, HCV, CMV, and EBV were ruled out as causative agents in this case. The patient's blood sample in the acute phase contained HEV RNA as well as IgM and IgG anti-HEV. HEV RNA was also detected in one of the FFP units transfused. The donor had no history of traveling abroad and had a normal ALT level at the time of donation. The PCR products from the patient and the donor showed complete identity for two distinct regions of HEV within open reading frame 1.

CONCLUSION

The patient was infected with HEV via transfused blood from a volunteer donor. A potential risk of posttransfusion hepatitis E should be considered even in nonendemic countries.

Characterization of Japanese swine and human hepatitis E virus isolates of genotype IV with 99 % identity over the entire genome

The full-length genomic sequences were determined of Japanese swine and human hepatitis E virus (HEV) isolates (swJ13-1 and HE-JA1, respectively) with 100 % identity in the partial sequence of open reading frame (ORF) 2 (ORF2, 412 nt). swJ13-1 was isolated from a 4-month-old farm pig born in Hokkaido, Japan, in 2002 and HE-JA1 was recovered from a 55-year-old patient who lived in Hokkaido and who had contracted sporadic acute hepatitis E in 1997. Both isolates consisted of 7240 nt, excluding the poly(A) tail, and contained three ORFs (ORFs 1-3) that encoded proteins of 1707, 674 and 114 aa. The overall nucleotide sequence identity between them was 99.0 % and the deduced amino acid sequence identities of ORFs 1-3 were 99.8, 100 and 100 %, respectively. The high degree of genomic similarity observed between swine and human HEV isolates in a restricted area of Japan further supports the finding that sporadic hepatitis E in Japan is a zoonosis.