A cross-sectional study of hepatitis E virus infection in healthy people directly exposed and unexposed to pigs in a rural community in northern Thailand

Systematic review and meta-analysis of hepatitis E seroprevalence in Southeast Asia: a comprehensive assessment of epidemiological patterns

The burden of hepatitis E in Southeast Asia is substantial, influenced by its distinct socio-economic and environmental factors, as well as variations in healthcare systems. The aim of this study was to assess the pooled seroprevalence of hepatitis E across countries within the Southeast Asian region by the UN division.The study analyzed 66 papers across PubMed, Web of Science, and Scopus databases, encompassing data from of 44,850 individuals focusing on anti-HEV seroprevalence. The investigation spanned nine countries, excluding Brunei and East Timor due to lack of data. The pooled prevalence of anti-HEV IgG was determined to be 21.03%, with the highest prevalence observed in Myanmar (33.46%) and the lowest in Malaysia (5.93%). IgM prevalence was highest in Indonesia (12.43%) and lowest in Malaysia (0.91%). The study stratified populations into high-risk (farm workers, chronic patients) and low-risk groups (general population, blood donors, pregnant women, hospital patients). It revealed a higher IgG-28.9%, IgM-4.42% prevalence in the former group, while the latter group exhibited figures of 17.86% and 3.15%, respectively, indicating occupational and health-related vulnerabilities to HEV.A temporal analysis (1987-2023), indicated an upward trend in both IgG and IgM prevalence, suggesting an escalating HEV burden.These findings contribute to a better understanding of HEV seroprevalence in Southeast Asia, shedding light on important public health implications and suggesting directions for further research and intervention strategies.Key pointsResearch QuestionInvestigate the seroprevalence of hepatitis E virus (HEV) in Southeast Asian countries focusing on different patterns, timelines, and population cohorts.FindingsSporadic Transmission of IgG and IgM Prevalence:• Pooled anti-HEV IgG prevalence: 21.03%• Pooled anti-HEV IgM prevalence: 3.49%Seroprevalence among specific groups:High-risk group (farm workers and chronic patients):• anti-HEV IgG: 28.9%• anti-HEV IgM: 4.42%Low-risk group (general population, blood donors, pregnant women, hospital patients):• anti-HEV IgG: 17.86%• anti-HEV IgM: 3.15%Temporal Seroprevalence of HEV:Anti-HEV IgG prevalence increased over decades (1987-1999; 2000-2010; 2011-2023): 12.47%, 18.43%, 29.17% as an anti-HEV IgM prevalence: 1.92%, 2.44%, 5.27%ImportanceProvides a comprehensive overview of HEV seroprevalence in Southeast Asia.Highlights variation in seroprevalence among different population groups.Reveals increasing trend in HEV seroprevalence over the years.Distinguishes between sporadic and epidemic cases for a better understanding of transmission dynamics.

Meta-analysis and moderator analysis of the seroprevalence of hepatitis E in South-Eastern Asia

By 2030, the World Health Organization wants to decrease viral hepatitis incidence and mortality by 90% and 65%, respectively. One of the agents responsible for the increased burden of viral hepatitis is the hepatitis E virus (HEV). This emerging pathogen is prevalent worldwide causing both acute and chronic infection. The rising risk profile of HEV has become a source of increased global public health concern. Despite this challenge, South-Eastern Asia (SEA), where many at-risk people are found, lacks uniform HEV prevalence data. Therefore, a meta-analysis was conducted to assess the overall prevalence of hepatitis E in SEA. Using R statistical software, a random effect model was used to estimate the logit-transformed prevalence. Moderator analyses were used to investigate the potential sources of variation. Thirty-two studies comprising 29,944 with 6806 anti-HEV antibody-positive individuals were evaluated. The overall HEV seroprevalence in SEA was 21% (95% confidence interval [CI]: 17-27) with high heterogeneity. At the country level, Laos has the highest prevalence estimate of 39% (CI: 16-69). Also, the studied population, year of publication, duration of sampling, and diagnostic method are significant HEV prevalence predictors accounting for 22.61% of the observed heterogeneity. The high HEV prevalence found in this study necessitates coordinated national and regional efforts to combat this emerging disease.

Assessing Behavioral Risk Factors Driving Zoonotic Spillover Among High-risk Populations in Myanmar

The increasing global emergence of zoonoses warrants improved awareness of activities that predispose vulnerable communities to greater risk of disease. Zoonotic disease outbreaks regularly occur within Myanmar and at its borders partly due to insufficient knowledge of behavioral risks, hindering participatory surveillance and reporting. This study employed a behavioral surveillance strategy among high-risk populations to understand the behavioral risks for zoonotic disease transmission in an effort to identify risk factors for pathogen spillover. To explore behavioral mechanisms of spillover in Myanmar, we aimed to: (1) evaluate the details around animal contact and types of interaction, (2) assess the association between self-reported unusual symptoms (i.e., any illness or sickness that is not known or recognized in the community or diagnosed by medical providers) and animal contact activities and (3) identify the potential risk factors including behavioral practices of self-reported illness. Participants were enrolled at two community sites: Hpa-An and Hmawbi in Southern Myanmar. A behavioral questionnaire was administered to understand participants' animal exposures, behaviors and self-reported illnesses. From these responses, associations between (1) animal contact activities and self-reported unusual illnesses, and (2) potential risk factors and self-reported unusual illness were tested. Contact with poultry seemed to be very frequent (91.1%) and many participants reported raising, handling and having poultry in their houses as well as slaughtering or being scratched/bitten by them, followed by contact with rodents (57.8%) and swine (17.9%). Compared to participants who did not have any unusual symptoms, participants who had unusual symptoms in the past year were more likely to have sold dead animals (OR = 13.6, 95% CI 6.8-27.2), slaughtered (OR = 2.4, 95% CI 1.7-3.3), raised (OR = 3.4, 95% CI 2.3-5.0) or handled animals (OR = 2.1, 95% CI 1.2-3.6), and had eaten sick (OR = 4.4, 95% CI 3.0-6.4) and/or dead animals (OR = 6.0, 95% CI 4.1-8.8) in the same year. Odds of having reported unusual symptoms was higher among those involved in animal production business (OR = 3.4, 95% CI 1.9-6.2) and animal-involved livelihoods (OR = 3.3, 95% CI 1.5-7.2) compared to other livelihoods. The results suggest that there is a high level of interaction between humans, livestock and wild animals in communities we investigated in Myanmar. The study highlights the specific high-risk behaviors as they relate to animal contact and demographic risk factors for zoonotic spillover. Our findings contribute to human behavioral data needed to develop targeted interventions to prevent zoonotic disease transmission at human-animal interfaces.

Insights into hepatitis E virus epidemiology in Croatia

BACKGROUND

Hepatitis E virus (HEV) is an emerging virus of global health concern. The seroprevalence rates differ greatly according to geographic region and population group.

AIM

To analyze the seroprevalence of HEV in exposed (animal-related professions) and nonexposed populations, as well as solid organ and hematopoietic stem cell transplant patients.

METHODS

Forestry workers (n = 93), hunters (n = 74), and veterinarians (n = 151) represented the exposed population. The general population (n = 126) and pregnant women (n = 118) constituted the control group. Transplant patients included liver transplant recipients (LTRs) (n = 83), kidney transplant recipients (KTRs) (n = 43), and hematopoietic stem cell transplant recipients (HSCRs) (n = 39). HEV immunoglobulin G antibodies were detected using the enzyme-linked immunosorbent assay and confirmed by the immunoblot test.

RESULTS

The HEV seroprevalence significantly differed between groups: Veterinarians 15.2%, hunters 14.9%, forestry workers 6.5%, general population 7.1%, and pregnant women 1.7%. In transplant patients, the seropositivity was highest in LTRs (19.3%), while in KTRs and HSCRs, the seroprevalence was similar to the general population (6.9% and 5.1%, respectively). A significant increase in seropositivity with age was observed from 2.9% in individuals less than 30 years to 23.5% in those older than 60 years. Sociodemographic characteristics (sex, educational level, area of residence, and number of household members), eating habits (game meat, offal, and pork products consumption), and environmental and housing conditions (drinking water supply, type of water drainage/sewer, waste disposal, domestic animals) were not associated with HEV seropositivity. However, individuals who reported a pet ownership were more often seropositive compared to those who did not have pet animals (12.5% vs 7.0%).

CONCLUSION

The results of this study showed that individuals in professional contact with animals and LTRs are at higher risk for HEV infection. In addition, age is a significant risk factor for HEV seropositivity.

Behavioral-biological surveillance of emerging infectious diseases among a dynamic cohort in Thailand

Background

Interactions between humans and animals are the key elements of zoonotic spillover leading to zoonotic disease emergence. Research to understand the high-risk behaviors associated with disease transmission at the human-animal interface is limited, and few consider regional and local contexts.

Objective

This study employed an integrated behavioral–biological surveillance approach for the early detection of novel and known zoonotic viruses in potentially high-risk populations, in an effort to identify risk factors for spillover and to determine potential foci for risk-mitigation measures.

Method

Participants were enrolled at two community-based sites (n = 472) in eastern and western Thailand and two hospital (clinical) sites (n = 206) in northeastern and central Thailand. A behavioral questionnaire was administered to understand participants’ demographics, living conditions, health history, and animal-contact behaviors and attitudes. Biological specimens were tested for coronaviruses, filoviruses, flaviviruses, influenza viruses, and paramyxoviruses using pan (consensus) RNA Virus assays.

Results

Overall 61/678 (9%) of participants tested positive for the viral families screened which included influenza viruses (75%), paramyxoviruses (15%), human coronaviruses (3%), flaviviruses (3%), and enteroviruses (3%). The most salient predictors of reporting unusual symptoms (i.e., any illness or sickness that is not known or recognized in the community or diagnosed by medical providers) in the past year were having other household members who had unusual symptoms and being scratched or bitten by animals in the same year. Many participants reported raising and handling poultry (10.3% and 24.2%), swine (2%, 14.6%), and cattle (4.9%, 7.8%) and several participants also reported eating raw or undercooked meat of these animals (2.2%, 5.5%, 10.3% respectively). Twenty four participants (3.5%) reported handling bats or having bats in the house roof. Gender, age, and livelihood activities were shown to be significantly associated with participants’ interactions with animals. Participants’ knowledge of risks influenced their health-seeking behavior.

Conclusion

The results suggest that there is a high level of interaction between humans, livestock, and wild animals in communities at sites we investigated in Thailand. This study highlights important differences among demographic and occupational risk factors as they relate to animal contact and zoonotic disease risk, which can be used by policymakers and local public health programs to build more effective surveillance strategies and behavior-focused interventions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07439-7.

Global infectious disease risks associated with occupational exposure among non-healthcare workers: a systematic review of the literature

Objectives

Employees in non-healthcare occupations may be in several ways exposed to infectious agents. Improved knowledge about the risks is needed to identify opportunities to prevent work-related infectious diseases. The objective of the current study was to provide an updated overview of the published evidence on the exposure to pathogens among non-healthcare workers. Because of the recent SARS-CoV-2 outbreaks, we also aimed to gain more evidence about exposure to several respiratory tract pathogens.

Methods

Eligible studies were identified in MEDLINE, Embase and Cochrane between 2009 and 8 December 2020. The protocol was registered with International Prospective Register of Systematic Reviews (CRD42019107265). An additional quality assessment was applied according to the Equator network guidelines.

Results

The systematic literature search yielded 4620 papers of which 270 met the selection and quality criteria. Infectious disease risks were described in 37 occupational groups; 18 of them were not mentioned before. Armed forces (n=36 pathogens), livestock farm labourers (n=31), livestock/dairy producers (n=26), abattoir workers (n=22); animal carers and forestry workers (both n=16) seemed to have the highest risk. In total, 111 pathogen exposures were found. Many of these occupational groups (81.1%) were exposed to respiratory tract pathogens.

Conclusion

Many of these respiratory tract pathogens were readily transmitted where employees congregate (workplace risk factors), while worker risk factors seemed to be of increasing importance. By analysing existing knowledge of these risk factors, identifying new risks and susceptible risk groups, this review aimed to raise awareness of the issue and provide reliable information to establish more effective preventive measures.

A systematic review of the epidemiology of Hepatitis E virus infection in South - Eastern Asia

Hepatitis E virus (HEV) infection is an emerging zoonotic viral disease, with an increasingly international public health challenge. Despite the concerns that the global disease burden may be underestimated. Therefore, evaluation of the disease epidemiology in South – eastern Asia through a systematic review will assist in unraveling the burden of the disease in the subregion. A priori protocol was prepared for the systematic review and followed by a literature search involving five electronic databases. Identified publications were screened for high quality studies and the elimination of bias and relevant data extracted. A total of 4157 citations were captured, and only 35 were included in the review. A wide range of HEV seroprevalence was recorded from 2% (urban blood donors in Malaysia) to 77.7% (lowland communities in Lao PDR). Sporadic HEV infection and epidemics were also detected in the subregion. Indicating hyperendemicity of the disease in South – eastern Asia.

Prevalence and phylogenetic analysis of hepatitis E virus in pigs in Vietnam

Background

Hepatitis E virus (HEV) is a zoonotic disease and has been reported around the world. The main objective of this study was to evaluate the sero-prevalence and phylogenetic analysis of HEV in Vietnam. Pig blood and fecal pooled samples were collected to assess the prevalence of HEV. We assessed the true prevalence (TP) of HEV from apparent prevalence (AP) by taking into account the sensitivity and specificity of diagnostic tests using a Bayesian approach. For phylogenetic analysis, the data compared with worldwide HEV reference strains including all eight genotypes (G1-G8) which were identified in previous study.

Results

A total of 475 sera and 250 fecal pooled samples were collected at slaughterhouses and pig farms from five provinces, in Viet Nam. Overall, the sero-AP of HEV was 58.53% (95% confidence interval: 53.95–62.70) while the sero-TP was slightly higher (65.43, 95% credible interval: 47.19–84.70). In terms of pooled samples, overall, the RNA-AP was 6.80% (95% confidence interval: 4.01–10.66). One strain in Hanoi, two strains in Dak Lak, seven strains in An Giang, four strains in Son La and two strains in Nghe An were isolated. The phylogenetic tree demonstrated that 19 Vietnamese strains were clustered into HEV 3 and 4.

Conclusions

This study provided evidence that HEV is circulating in domestic pigs in Vietnam. From a public health perspective, it is very important to raise public awareness for high-risk groups (e.g. slaughterhouse workers, pig traders, farmers and market sellers) who have more opportunities to come in contact with pig and contaminated meats.

A Nationwide Survey of the Seroprevalence of Hepatitis E Virus Infections Among Blood Donors in Thailand

Hepatitis E virus (HEV) is a common cause of acute hepatitis infections. Our previous 3-year study at two large Thai hospitals established an occurrence of 4-5% of HEV infections from swine HEV genotype 3 in suspected acute hepatitis patients, with the high incidence in older adults. This study was a serosurvey to determine the prevalence of HEV infections among Thai adults. We obtained sera from 630 healthy blood donors with a median age of 38 (18-64) years who attended Thai Red Cross transfusion units throughout Thailand. The donors were domiciled in 16 provinces in the northern (n = 159), central (n = 193), northeastern (n = 158), and southern (n = 120) regions. The seroprevalence of IgG antibody to HEV (anti-HEV) was determined by the EUROIMMUN test kit, using indirect enzyme-linked immunosorbent assay (ELISA) based on recombinant antigens derived from ORF2 of HEV genotypes 1 and 3. Demographic data, including information related to HEV infection risk (the number of pigs and the proportion of Muslims in each province), were also obtained. The overall anti-HEV prevalence among Thai adults was 29.7%. The frequencies of anti-HEV found in the northern (28.9%, 95% confidence interval [CI] = 22.4-36.4), northeastern (34.8%, 95% CI = 27.8-42.5), and central (35.8%, 95% CI = 29.3-42.7) regions were similar, whereas the frequency in the southern (14.2%, 95% CI = 9.0-21.5) region, known to have a large Muslim population, was low. An increasing frequency of the specific antibody was observed among the elderly. A low HEV infection rate was associated with an Islamic population where there are low number of pigs and low swine consumption. Furthermore, the higher anti-HEV incidences in the northeastern provinces might relate to the local cultural practice of consuming undercooked pork. Besides the need for an HEV vaccination in the future, there is a requirement for rapid early diagnosis; the undertaking of prevention-management campaigns might also reduce the number of infected patients.

Emerging zoonotic viral infections of occupational health importance

Emerging viral infections represent a public health risk pointed out by the spreading of pathogens with potential zoonotic risk. Moreover, the risk of zoonosis has probably been underestimated in occupational settings. A literature review between 2007 and 2018 was performed to identify evidences concerning the epidemiological associations between some emerging viruses and occupational diseases. Observational studies and case-reports were selected and analyzed. West Nile Virus (WNV) disease, Crimean-Congo Hemorrhagic Fever (CCHF) disease and Hepatitis E virus (HEV) infection were included in the review for their potential zoonotic transmission. The most important risk factor for acquiring WNV infection and CCHF infection is the exposure to infected mosquitoes and ticks, respectively; therefore, outdoor workers are at risk of infection. HEV is responsible for epidemics and endemics of acute hepatitis in humans, that can become infected through waterborne, foodborne and zoonotic transmission routes. A total of 10, 34 and 45 eligible studies for WNV, CCHF virus (CCFHV) and HEV, respectively, were analyzed by year, country, study design, risk group and outcomes. The occupational risk groups mainly included farm and agricultural workers, veterinarians, slaughterers, animal handlers, healthcare workers and soldiers. These findings support the need to develop effective interventions to prevent transmission of emerging viruses.

Hepatitis E virus infection in swine workers: A meta-analysis

Hepatitis E virus (HEV) infects both humans and animals. Swine has been confirmed to be the principal natural reservoir, which raises a concern that HEV infection would be substantially increasing among swine workers. The present study calculated the pooled prevalence of IgG antibodies against HEV among swine workers and the general population in previous cross-sectional studies. We conducted a meta-analysis comparing the prevalence of HEV infection between swine workers and the general population, including local residents, blood donors and non-swine workers. Through searches in three databases (PubMed and OVID in English, and CNKI in Chinese) and after study selection, a total of 32 studies from 16 countries (from 1999 through 2018) were included in the meta-analysis. A random-effect model was employed in the study; an I ² statistic assessed heterogeneity, and the Egger's test detected publication bias. The comparative prevalence of anti-HEV IgG was pooled from the studies. Compared to the general population, the prevalence ratio (PR) for swine workers was estimated to be 1.52 (95% CI 1.38-1.76) with the I ² being 71%. No publication bias was detected (p = 0.40). A subgroup analysis further indicated increased prevalence of anti-HEV IgG in the swine workers in Asia (PR = 1.49, 95% CI: 1.35-1.64), in Europe (PR = 1.93, 95% CI: 1.49-2.50) and in all five swine-related occupations, including swine farmers, butchers, meat processors, pork retailers and veterinarians (PR ranged between 1.19 and 1.75). In summary, swine workers have a relatively higher prevalence of past HEV infection, and this finding is true across swine-related occupations, which confirms zoonotic transmission between swine and swine workers.

Transmission and Epidemiology of Hepatitis E Virus Genotype 3 and 4 Infections

Following the introduction of robust serological and molecular tools, our understanding of the epidemiology of zoonotic hepatitis E virus (HEV) has improved considerably in recent years. Current thinking suggests that consumption of pork meat products is the key route of infection in humans, but it is certainly not the only one. Other routes of infection include environmental spread, contaminated water, and via the human blood supply. The epidemiology of HEV genotype (gt)3 and gt4 is complex, as there are several sources and routes of infection, and it is likely that these vary between and within countries and over time.

Evidence of increased Hepatitis E virus exposure in Lao villagers with contact to ruminants

Although pigs are the main reservoir, ruminants have also been shown to be susceptible to hepatitis E virus (HEV). We investigated zoonotic transmission of HEV in rural settings of Lao People's Democratic Republic (Lao PDR) where humans are in close contacts with ruminants and where pigs are rare. Villagers with (n = 171, risk group) and without (n = 155, control group) cattle were recruited in seven villages in Vientiane Capital. Owners of pigs were excluded. Blood, as well as information on socio-demographics, animal contact, dietary habits and awareness of zoonoses were collected to assess risk factors. Blood and rectal swabs were collected from cattle (n = 173) and other ruminants (27 goat, 5 buffaloes) to measure anti-HEV antibody and virus prevalence. A similar anti-HEV antibody seroprevalence was found in cattle (6.8%) and other ruminants (8%). HEV RNA was detected in none of the animal rectal swabs and human sera. Anti-HEV IgG seroprevalence was higher in cattle farmers than in the control group (59.1% vs. 43.9%, p = 0.008) and increased significantly with age. Other risk factors included male gender, close contact with cattle and consumption of undercooked meat. We find that HEV is highly endemic in rural Laos and provide first evidence that HEV circulates in free-roaming ruminants with open access to village water sources. Despite some awareness about hygiene, villagers are likely constantly exposed to zoonotic diseases by dietary and lifestyle habits. Cattle farmers had a higher risk of HEV infection than other villagers. Our study highlights the need to raise the awareness of the rural population about water- and food-borne pathogens, and about the role of cattle as a possible source of infection. The knowledge gained on local risk factors and husbandry conditions should guide future awareness raising campaigns and promote appropriate hygienic measures including handwashing and the consumption of safe food and water.

Recent knowledge on hepatitis E virus in Suidae reservoirs and transmission routes to human

Hepatitis E virus (HEV) causes self-limiting acute hepatitis in humans that can eventually result in acute liver failures or progress to chronic infections. While in tropical and sub-tropical areas, HEV infections are associated with important waterborne epidemics, in Northern countries, HEV infections are autochthonous with a zoonotic origin. In the past decade, it has become clear that certain HEV genotypes are zoonotic and that swine, and more generally Suidae, are the main reservoir. Zoonotic transmissions of the virus may occur via direct contact with infected pigs, wild boars or consumption of contaminated meat. This review describes the current knowledge on domestic and wild Suidae as reservoirs of HEV and the evidence of the different routes of HEV transmission between these animals and humans.

Hepatitis E virus and related viruses in wild, domestic and zoo animals: A review

Hepatitis E is a human disease mainly characterized by acute liver illness, which is caused by infection with the hepatitis E virus (HEV). Large hepatitis E outbreaks have been described in developing countries; however, the disease is also increasingly recognized in industrialized countries. Mortality rates up to 25% have been described for pregnant women during outbreaks in developing countries. In addition, chronic disease courses could be observed in immunocompromised transplant patients. Whereas the HEV genotypes 1 and 2 are mainly confined to humans, genotypes 3 and 4 are also found in animals and can be zoonotically transmitted to humans. Domestic pig and wild boar represent the most important reservoirs for these genotypes. A distinct subtype of genotype 3 has been repeatedly detected in rabbits and a few human patients. Recently, HEV genotype 7 has been identified in dromedary camels and in an immunocompromised transplant patient. The reservoir animals get infected with HEV without showing any clinical symptoms. Besides these well-known animal reservoirs, HEV-specific antibodies and/or the genome of HEV or HEV-related viruses have also been detected in many other animal species, including primates, other mammals and birds. In particular, genotypes 3 and 4 infections are documented in many domestic, wildlife and zoo animal species. In most cases, the presence of HEV in these animals can be explained by spillover infections, but a risk of virus transmission through contact with humans cannot be excluded. This review gives a general overview on the transmission pathways of HEV to humans. It particularly focuses on reported serological and molecular evidence of infections in wild, domestic and zoo animals with HEV or HEV-related viruses. The role of these animals for transmission of HEV to humans and other animals is discussed.

Seroprevalence and risk factors of hepatitis E virus infection among the Korean, Manchu, Mongol, and Han ethnic groups in Eastern and Northeastern China

Hepatitis E virus (HEV) infection is a serious public health concern in developing countries. China is regarded as an HEV-endemic area, but epidemiological data for HEV among different nationalities is limited. This study was conducted to estimate the seroprevalence and risk factors of HEV infection in Koreans (n = 520), Manchus (n = 303), Mongols (n = 217), and Hans (n = 802) in Eastern and Northeastern China between 2013 and 2015. A total of 366 (19.87%) out of 1842 samples were seropositive for IgG or IgM HEV-antibodies detected by enzyme-linked immunoassays. Among these groups, the Mongols had the highest seroprevalence of HEV infection (25.35%, 55/217), followed by the Koreans (23.65%, 123/520), the Manchus (19.80%, 60/303), and the Hans (15.96%, 128/802). Multiple analysis showed that the gender, consumption of raw/undercooked meat, source of drinking water, residence area, and age were significantly associated with HEV infection in four ethnic groups. The present results indicated that HEV infection was prevalent in Mongols, Koreans, Manchus, and Hans in the surveyed regions, which demonstrated the higher risk of transmitting HEV in multiple nationalities in Eastern and Northeastern China.

Hepatitis E Virus in Pork and Variety Meats Sold in Fresh Markets

Swine is an economically important livestock, yet pork consumption and close contact with pigs are associated with the risk of hepatitis E virus (HEV) infection. Limited data on the prevalence of HEV in Southeast Asia have mainly examined farm animals. To investigate the potential zoonotic transmission of HEV from dietary consumption of pork and variety meats (i.e., offal or organ meats), we obtained 1090 liver, 559 pork meat, and 556 intestine samples from fresh markets in the Bangkok metropolitan area between November 2014 and February 2015. The presence of HEV was assessed using reverse-transcription polymerase chain reaction. Concurrently, 720 bile and 553 fecal samples from a slaughterhouse were also examined. Overall, HEV RNA was found in 0.23 % of the market samples and 3.93 % of the slaughterhouse samples. Fecal and bile samples were more likely to test positive compared to liver, pork, and intestine samples (p < 0.001). Phylogenetic analysis showed that all HEV sequences obtained in this study formed a cluster closely related to genotype 3f. Pork and variety meats derived from pigs are commonly sold in fresh markets throughout Southeast Asia. Here, a relatively low HEV prevalence from pork and variety meats sold in Bangkok was found. Additional studies will be required to further assess potential dietary transmission of HEV elsewhere in the region.

Hepatitis E virus seroprevalence among farmers, veterinarians and control subjects in Jilin province, Shandong province and Inner Mongolia Autonomous Region, China

China is commonly considered to be a HEV-endemic region but limited epidemiological data for HEV among farmers and veterinarians are available. Thus, a case-control study was carried out to detect the seroprevalence and assess potential risk factors associated with the acquisition of HEV infection by farmers and veterinarians in China from July 2013 to May 2015. Three hundred veterinarians and 600 farmers recruited from Jilin province, Shandong province, and Inner Mongolia Autonomous Region and 600 control subjects matched by gender, age, and residence were detected for the presence of anti-HEV IgG and IgM antibodies using enzyme immunoassays. The seroprevalences of HEV infection in farmers, veterinarians, and control subjects were 34.8%, 26.7%, and 20.2%, respectively. Farmers (P < 0.001) and veterinarians (P = 0.027) have significantly higher seroprevalence than control subjects. The highest seroprevalence of HEV infection was detected in swine farmers (49.1%) and the lowest seroprevalence was found in cattle farmers (26.5%). In veterinarians, farm animal veterinarians have a higher seroprevalence than pet veterinarians, but the difference was not significant (P > 0.05). Residence area, contact with swine and exposure with soil were significantly associated with HEV infection in the study farmers; contact with swine and source of drinking water were significantly associated with HEV infection in the study veterinarians. These results implied the high prevalence of HEV and the considerable potential for the dissemination of HEV infection in farmers and veterinarians in China. J. Med. Virol. 89:872-877, 2017. © 2016 Wiley Periodicals, Inc.

Hepatitis E virus as an emerging zoonotic pathogen

Hepatitis E outbreaks are a serious public health concern in developing countries. The disease causes acute infections, primarily in young adults. The mortality rate is approximately 2%; however, it can exceed 20% in pregnant women in some regions in India. The causative agent, hepatitis E virus (HEV), has been isolated from several animal species, including pigs. HEV genotypes 3 and 4 have been isolated from both humans and animals, and are recognized as zoonotic pathogens. Seroprevalence studies in animals and humans indirectly suggest that HEV infections occur worldwide. The virus is primarily transmitted to humans via undercooked animal meats in developed countries. Moreover, transfusion- and transplantation-mediated HEV infections have recently been reported. This review summarizes the general characteristics of hepatitis E, HEV infection status in animals and humans, the zoonotic transmission modes of HEV, and HEV vaccine development status.

Seroepidemiology of Hepatitis E in Selected Population Groups in Croatia: A Prospective Pilot Study

Hepatitis E has become an emerging infection in many European countries. We analysed the prevalence of hepatitis E virus (HEV) infection in selected population groups in Croatia. Overall HEV IgG seropositivity was 5.6%, while 1.9% participants showed IgM antibodies suggestive of recent infection. No IgM-positive sample was positive for HEV RNA. HEV IgG antibodies were most prevalent in alcohol abusers (8.9%) and war veterans (8.6%), compared with 6.1% among injecting drug users and 2.7% in healthcare professionals. No individual with high-risk sexual behaviour tested HEV seropositive. HEV IgG positivity increased significantly with age from 1.8% to 2.3% in individuals younger than 40 years to 11.3% in individuals older than 50 years (P = 0.023). The mean age of HEV-positive participants was significantly higher than that of HEV-negative participants (50.9 ± 11.8 years versus 41.2 ± 11.8 years, P = 0.008). Seroprevalence rates were significantly higher in residents of suburban and rural areas compared with residents of urban areas (14.5% versus 2.5%, P = 0.003). Additionally, an increasing prevalence of HEV IgG antibodies was observed from 1.8% in participants living in families with two household members to 12.1% in those living with more than four members (P = 0.046). Gender, marital status, educational level, sexual orientation, source of drinking water, history of blood transfusions, surgical procedures, tattooing and travelling were not associated with HEV seroprevalence. Logistic regression showed that living in suburban/rural areas was the main risk factor for HEV seropositivity (OR = 6.67; 95%CI = 1.89-25.0; AOR = 7.14, 95%CI = 1.89-25.0).

Low frequency of acute hepatitis E virus (HEV) infections but high past HEV exposure in subjects from Cambodia with mild liver enzyme elevations, unexplained fever or immunodeficiency due to HIV-1 infection

BACKGROUND

In Cambodia, previous studies conducted on hepatitis E virus (HEV) infection are scant, sometimes old, and showed inconsistent results. Moreover, there is no data about HEV infection in Cambodian HIV-1-infected patients.

OBJECTIVES

To assess the occurrence of acute HEV infections and the level of past HEV exposure in one Mekong country.

STUDY DESIGN

Using anti-HEV IgM and HEV RNA detection, we retrospectively investigated the presence of acute HEV infection in 825 individuals, including 350 subjects with or without fever, 300 subjects with or without liver enzyme elevations (LEE) and 175 antiretroviral treatment (ART)-naïve, severely immunocompromised HIV-1-infected patients. The detection of anti-HEV IgG was also performed to assess ancient HEV exposure.

RESULTS

Nine individuals tested positive for anti-HEV IgM yielding an overall rate of 1.1% (95% confidence interval (CI), 0.5-2.0). We did not find significant differences for anti-HEV IgM rates between subjects with unexplained fevers (1.5%) and those with malaria or dengue-associated fever (1.7%) or non-febrile individuals (0%) (P=0.49), and between subjects with (1.5%) and without (2.0%) LEE (P=0.87). No HIV-infected patient tested positive for anti-HEV IgM. HEV RNA was not detected in all tested plasma specimens (n=578). Overall, the anti-HEV IgG prevalence rate was 30.1% (95% CI, 27.0-33.2).

CONCLUSIONS

The scarcity of recent HEV infection contrasted with the high level of past HEV exposure. The role of HEV in liver disease is likely minor in Cambodia since no HEV RNA was detected in our studied populations, including HIV-positive patients with severe immunodepression.

Pork consumption and seroprevalence of hepatitis E virus,Thailand, 2007-2008

The nationwide seroprevalence of hepatitis E IgG was determined among young men in Thailand. Overall seroprevalence was 14% (95% CI 13%–15%); range by province was 3%–26%. Seroprevalence was lowest in the south, an area predominantly occupied by persons of the Islam religion, whose dietary laws proscribe pork.

Prevalence of Hepatitis E Virus among Adults in South-West of Iran

Background. Knowledge regarding prevalence of HEV in general population can be an indicator of the public health and hygiene. Therefore, this study was conducted to evaluate the prevalence of HEV among adults in South-West of Iran. Methods. Blood samples were taken from 510 participants, 206 (40.4%) males and 304 (59.6%) females from February to July 2014. Detection of anti-HEV IgG and IgM antibodies was carried out by ELISA test. Results. The overall anti-HEV IgG and IgM prevalence rates were 46.1% and 1.4%, respectively. Anti-HEV IgG and IgM seropositivity were not statistically associated with gender and race/ethnicity. Meanwhile, there were significant differences between the age groups regarding HEV IgG and IgM seropositivity. HEV IgG seroprevalence increased with age from 14.3% in subjects aged 18-30 years to 71.4% in persons over 71 years old, and considerably individuals aged 61 to 70 years had the highest HEV prevalence (90.9%). Also, 5.7% in the age group 18-30 years and 2.2% in the age group 31-40 years were positive for anti-HEV IgM antibodies and the highest rate was observed in subjects aged 18-30 years. Conclusion. In conclusion, high HEV IgG seroprevalence of 46.1% was observed among adults in South-West of Iran.

Prevalence of Endemic Pig-Associated Zoonoses in Southeast Asia: A Review of Findings from the Lao People's Democratic Republic

The increasing intensification of pork production in southeast Asia necessitates an urgent requirement to better understand the dual impact of pig-associated zoonotic disease on both pig production and human health in the region. Sharing porous borders with five countries and representing many regional ethnicities and agricultural practices, the Lao People's Democratic Republic (Lao PDR) appears well placed to gauge the levels of pig-associated zoonoses circulating in the wider region. Despite this, little is known about the true impact of zoonotic pathogens such as leptospirosis, Trichinella, hepatitis E virus (HEV), Japanese encephalitis (JE), and Taenia solium on human health and livestock production in the country. A comprehensive review of the published prevalences of these five pig-associated zoonoses in Lao PDR has demonstrated that although suspicion remains high of their existence in pig reservoirs across the country, epidemiological data are scarce; only 31 epidemiological studies have been undertaken on these diseases in the past 25 years. A greater understanding of the zoonoses prevalence and subsequent risks associated with pork production in the southeast Asian region could help focus public health and food safety interventions at key points along the value chain, benefiting both livestock producers and the broader animal and human health systems in the region.

Cultural drivers and health-seeking behaviours that impact on the transmission of pig-associated zoonoses in Lao People's Democratic Republic

Pig rearing is an important income source in the Lao People's Democratic Republic (PDR), with many smallholder farmers using traditional free-range pig production systems. Despite the potentially significant health risks posed by pig production regarding pig-associated zoonoses, information on the sociocultural drivers of these zoonoses is significantly lacking. This review summarises the existing sociocultural knowledge on eight pig-associated zoonoses suspected to be endemic in Southeast Asia: brucellosis, Q fever (Coxiella burnetii), trichinellosis, hepatitis E virus, leptospirosis, Japanese encephalitis, Streptococcus suis and Taenia solium taeniasis-cysticercosis. It summarises current knowledge on these diseases grouped according to their clinical manifestations in humans to highlight the propensity for underreporting. A literature search was conducted across multiple databases for publications from 1990 to the present day related to the eight pig-associated zoonoses and the risk and impact connected with them, with Lao PDR as a case study. Many of these pig-associated zoonoses have similar presentations and are often diagnosed as clinical syndromes. Misdiagnosis and underreporting are, therefore, substantial and emphasise the need for more robust diagnostics and appropriate surveillance systems. While some reports exist in other countries in the region, information is significantly lacking in Lao PDR with existing information coming mainly from the capital, Vientiane. The disease burden imposed by these zoonoses is not only characterised by morbidity and mortality, but directly impacts on livelihoods through income reduction and production losses, and indirectly through treatment costs and lost work opportunities. Other factors crucial to understanding and controlling these diseases are the influence of ethnicity and culture on food-consumption practices, pig rearing and slaughter practices, hygiene and sanitation, health-seeking behaviours and, therefore, risk factors for disease transmission. Published information on the knowledge, attitudes and beliefs of people regarding pig zoonoses and their risk factors is also extremely limited in Lao PDR and the broader Southeast Asian region. The need for more transdisciplinary research, using a One Health approach, in order to understand the underlining social determinants of health and their impacts on health-seeking behaviours, disease transmission and, ultimately, disease reporting, cannot be more emphasized.

The prevalence of hepatitis E virus infections among swine, swine farmers and the general population in Guangdong Province, China

Hepatitis E virus (HEV) infection is widespread in China, but few studies have been carried out in Guangdong Province. This study aimed to characterize the prevalence of HEV infections among swine, swine farmers and the general population in Guangdong Province. We conducted an epidemiological study that included swine, swine farmers and health examination attendees in Guangdong from 2011 to 2013. The overall seroprevalence of anti-HEV antibodies in swine was 64.7%. The results revealed that growing pigs, sows and boars (OR ranges from 3.5 to 21.5) have a higher risk than nursery pigs. HEV RNA in swine bile showed that HEV is epidemic in swine in the Pearl River Delta, with the highest prevalence of 22.73% in Foshan. Some genomes of HEV strains from each district were sequenced. Phylogenetic analysis of partial open reading frame 2 (ORF2) shows that they belong to genotype IV and are most closely related to isolates from China. In total, 307 participants were enrolled in the study, including 114 swine farmers and 193 attendees from hospitals. IgG anti-HEV was detected in 48.25% of swine farmers and in 38.34% of the general population. Seroprevalence rates were almost stratified by age, with a higher positive rate for males compared to females across all age groups. Women on swine farms appeared to have a lower risk of infection compared to the general population, revealing that the risk factors for HEV infection are not unique. The results suggested that there were other risk factors for HEV infection. HEV infection is prevalent in Guangdong, but due to the small sample sizes, more investigations are needed to assess the potential impact of HEV infection, and many additional risk factors should be considered.

Light and Darkness: Prevalence of Hepatitis E Virus Infection among the General Population

Human hepatitis E virus (HHEV) spreads early in life among the population in areas endemic for genotype 1 and infects mainly adults in areas endemic for genotype 3, where it would be responsible for about 10% of cases of suspected acute viral hepatitis of unknown etiology and for a number of subclinical, unrecognized infections. The overall prevalence of antibody to HHEV is high in most of the former areas and low in most of the later ones, but wide regional differences have been recorded in both cases. "Hot spots" of HHEV infection would exist for both types of strains in particular regions or among particular populations of the world. Studies on pork derivatives, shellfish bivalves, and vegetables for HHEV contamination at the sale point need to be extended for evaluating the impact of the agent on food safety, and the meaning of the finding of HHEV genotype 1 genomes in urban sewage from developed countries should be established through active surveillance. Consensus about technical issues in regard to anti-HEV testing would improve the knowledge of the HHEV epidemiology. Studies in particular regions and populations, and introduction of molecular diagnosis in the clinical setting as a routine tool, would also be required.

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.

Seroprevalence of Hepatitis E Virus Infection among Swine Farmers and the General Population in Rural Taiwan

Objectives

Hepatitis E virus (HEV) is an emerging pathogen. We evaluated the seroprevalence of HEV infection among swine farmers and the general population in Taiwan, a nonendemic country.

Methods

We conducted a cross-sectional seroepidemiologic study in rural Taiwan in 2012 and 2013. The study included swine farmers, health examination attendees, pregnant women, and students. A commercial enzyme-linked immunosorbent assay was used to detect immunoglobulin G (IgG) and IgM against HEV. Pertinent information was collected using a questionnaire.

Results

In total, 660 participants were enrolled in the study, including 156 swine farmers, 314 health examination attendees, 100 pregnant women, and 90 students. IgG anti-HEV was detected in 29.5% of swine farmers, 11.5% of health examination attendees, 2% of pregnant women, and 1.1% of students. Two subjects were positive for IgM anti-HEV. Logistic regression analysis revealed that swine farmers had an approximately 3.5-fold increased risk (odds ratio [OR], 3.46; 95% confidence interval [CI], 1.91–6.27; p<0.0001) for being seropositive for IgG anti-HEV as compared to the general population. Age was positively associated with seropositive rate (OR, 1.07 per year; 95% CI, 1.05–1.09; p<0.0001).

Conclusion

HEV infection is prevalent in Taiwan. The seroprevalence of HEV infection is high in swine farmers and in the elderly population.