Epidemiological and genetic analysis of a 2014 outbreak of hepatitis A in Japan

A case of post-outbreak acute hepatitis a in a Japanese man who have sex with men infected with RIVM-HAV16-090 strain

AIM

Hepatitis A outbreaks among men who have sex with men (MSM) are a growing global concern. We present a case report of acute hepatitis A in a Japanese MSM who acquired the infection after the conclusion of a recent hepatitis A outbreak in Japan during his subsequent visit to Taiwan.

CASE PRESENTATION

A 27-year-old male had experienced fever, headache, and loss of appetite over the previous eight days. After his jaundiced skin was noted during a routine health examination, he visited our outpatient department that same day. The severe liver dysfunction detected in blood tests necessitated hospitalization for acute hepatitis. Subsequent tests revealed positive HA-IgM antibodies, confirming acute hepatitis A. Further inquiry revealed the patient's MSM status and recent sexual encounter one and a half months earlier during a visit to Taiwan. With conservative treatment, his condition improved and he was discharged after 12 days. Phylogenetic analysis extracted from his stool sample confirmed that the hepatitis A virus (HAV) strain was RIVM-HAV16-090, consistent with strains observed in previous hepatitis outbreaks among MSM populations.

CONCLUSION

To the best of our knowledge, this is the first case report of acute hepatitis A in a Japanese MSM sporadically infected with the RIVM-HAV16-090 strain since the end of the outbreak. This case underscores the persistent risk of hepatitis A transmission among MSM despite the cessation of the outbreak, emphasizing the importance of targeted vaccination campaigns, sexual health education, and ongoing vigilance in mitigating the risk of hepatitis A transmission among MSM.

Hepatitis A epidemics in Japan, France, and Thailand from 2007 to 2021, highlighting a post-COVID-19 decline

Hepatitis A infection is an acute hepatitis disease transmitted through contaminated water, food, and sexual contact, especially among men who have sex with men (MSM). This retrospective cohort study analyzed trends in hepatitis A infection in Japan, France, and Thailand from 2007 to 2021 to investigate varied epidemic trends including the MSM pandemic and the COVID-19 pandemic under different public health conditions. We analyzed annual and monthly number of cases using the national surveillance databases of Japan, France, and Thailand. We statistically evaluated the decrease in hepatitis A after the COVID pandemic. Hepatitis A average incidence in Japan, France, and Thailand was 0.21, 1.79, and 0.75, respectively. Outbreaks were recorded in 2010, 2014, and 2018 for Japan, 2009 and 2017 for France, and 2012 and 2017 for Thailand. In 2012, a hepatitis A outbreak was recorded at an ice manufacturing factory in Thailand. In Japan, in 2014, 80.5% of cases were transmitted by contaminated seafood or water. Hepatitis A increased during 2017-2018 (324% in 2018 Japan, 489% in 2017 France, 166% in Thailand), possibly linked to the global MSM pandemic. After the COVID-19 pandemic, the cases significantly decreased in all three countries (p < 0.001). The characteristics of hepatitis A epidemic may reflect the activities of people, including high-risk groups.

Recent advances in hepatitis A virus research and clinical practice guidelines for hepatitis A virus infection in Japan

In 2018, there was a hepatitis A outbreak in Japan, and hepatitis A virus (HAV) infection is considered a sexually transmitted disease. In general, patients with hepatitis A should be given attention, and this disease should be prevented more than ever. The Japan Agency for Medical Research and Development (AMED) Hepatitis A and E viruses (HAV and HEV) Study Group has worked on the project to create "Recent Advances in Hepatitis A Virus (HAV) Research and Clinical Practice Guidelines for HAV Infection in Japan". The group consists of expert hepatologists and virologists who gathered at virtual meeting on August 5, 2023. Data about the pathogenesis, infection routes, diagnosis, complications, several factors for the severities, vaccination, and current and future treatments for hepatitis A were discussed and debated for a draft version. The participants assessed the quality of cited studies. The finalized recommendations are presented in this review. The recent advances in HAV research and clinical practice for HAV infection in Japan, have been reviewed by the AMED HAV and HEV Study Group.

Epidemiological characteristics of acute hepatitis A, 2013-2016: a cross-sectional study in Morocco

BACKGROUND

Hepatitis A virus (HAV) is the common cause of acute hepatitis worldwide. Indeed, hepatitis A is endemic in developing countries such in Morocco and most residents are exposed in childhood. The characterisation of circulating strains of HAV remains crucial to understand the virological evolution and geo-temporal characteristics, which are essential for controlling infections and outbreaks. The purpose of the current study was the detection and characterisation of HAV strains circulating in Morocco by performing serological test, RT-PCR, sequencing and phylogenetic analysis.

METHODS

In this cross-sectional study, 618 suspected acute hepatitis cases were examined by Architect HAV abIgM. Of the 162 positives, 64 underwent RNA extraction. None of the suspected cases was immune to HAV and none of them had received a blood transfusion. Samples found positive by RT-PCR using primers targeting the VP1/VP2A junction and the VP1/VP3 capsid region of HAV were subjected to sequencing and phylogenetic analyses.

RESULTS

HAV Acute infection rate was 26.2% [95% CI, 22.8-29.9], while viraemia reached 45% (29/64) after amplification of the VP3/VP1 region. Phylogenetic analysis of the VP1/2A segment revealed the presence of sub-genotypes IA and IB. Eighty-seven percent of the strains belonged to the subgenotype IA, while twelve percent to IB subgenotype.

CONCLUSION

This first molecular study of acute hepatitis A in Morocco provided information about genetic diversity of HAV, revealing the co-circulating of only two subgenotypes (IA and IB). Notably, subgenotype IA was found to be the predominant subgenotype in Morocco.

Hepatitis A virus subgenotypes in Latvia, 2008-2021

BACKGROUND

In Latvia outbreaks of the HAV were observed between 2008 and early 2010 and again in 2017-2018. However, the risks of introducing and spreading infection still exist, as the virus spreads easily when personal hygiene is not followed.

METHODS

To determine the spread of HAV subgenotypes in the territory of Latvia the VP1/P2A genomic region of HAV was amplified and sequenced for 259 case serum samples. The study carried out a molecular biological investigation and molecular epidemiological investigation. Demographic data (sex, age), disease data (hepatitis symptoms, hospitalization, vaccination) and epidemiology data (part of the outbreak, possible source of infection, recent travel) were collected. Based on the obtained sequences, the phylogenetic tree was built and analyzed for the homology and belonging to different isolated HAV clusters from other countries.

RESULTS

From the obtained data, it was concluded that HAV subgenotype IA had 13 clusters and 12 sporadic cases, HAV subgenotype IB had eight clusters and 11 sporadic cases, HAV subgenotype IIIA had one cluster and nine sporadic cases. It was found that the sources of infection among the investigated cases were different, they were mostly associated with contact with a patient with HAV, travel, as well as between persons who inject drugs and men who have sex with men, and the prevalence of HAV similar sequences was observed in different years. It was concluded that patients with HAV subgenotype IA had the longest hospitalization duration and averaged 9.3 days, while patients with subgenotype IB - 7.3 days, subgenotype IIIA - 7.7 days. Analyzing the data on vaccination, it was found that mostly all were not vaccinated or had an unknown vaccination status.

CONCLUSIONS

All of this has led to the conclusion that the application of molecular biological methods of the HAV and a careful analysis of epidemiological data can help to better understand the ways of spreading the infection, investigate local outbreaks, detect cases of imported infection and track the recirculation of the virus.

Seroepidemiology of hepatitis A virus infection in Japan: An area of very low endemicity

The incidence of hepatitis A virus (HAV) infection has declined significantly worldwide, including in Japan. A nationwide seroepidemiological study on hepatitis A in Japan has taken place almost every 10 years since 1973, and the last study was performed in 2003. In the present study, we describe the latest seroepidemiological pattern of hepatitis A in Japan using 7867 serum specimens obtained from healthy individuals collected between 2013 and 2017, approximately 10 years after the last study. Among them, 223 were anti-HAV positive. About 68% of individuals aged 60 years and older had anti-HAV antibodies, whereas only 1.1% of those aged below 60 years old had immunity; thus, almost all individuals younger than 60 years of age were HAV susceptible. In comparison with previous investigations, the susceptible population has increased and aged. According to data from the National Epidemiological Surveillance of Infectious Diseases (NESID) program, between 1989 and 2016, the proportion of patients with hepatitis A aged 60 years and older continuously increased with each year. The NESID data also suggested that recently, typical large foodborne outbreaks of hepatitis A have become rare, and cases tend to be reported among at-risk groups; overseas travelers contributed to 25% of hepatitis A cases, and in 2018, the first nationwide hepatitis A outbreak that affected mostly men who have sex with men was reported. The purpose of this study was to determine the current status of HAV infection in Japan, based on both seroepidemiology and the national surveillance data from the NESID.

Imported Infectious Diseases, Tropical Diseases and Local Endemic Infectious Diseases in Japan

We aimed to describe the historical perspectives and the current epidemiology of tropical, imported and local endemic infectious diseases in Japan in this review. Public health legislation for infectious diseases and immigration statistics were overviewed to provide the background of the infectious disease situation in Japan. Many tropical diseases were successfully controlled and eliminated in the latter half of the 20th century and the majority of those diseases are imported today. The trend of the main 15 imported infectious diseases before the advent of COVID-19 was summarized as well as local endemic infectious diseases in Japan. Transmission risks of traditional cuisines, lifestyles and nature exposures in Japan are introduced to guide clinicians for travel advice to prevent those local infectious diseases.

Hepatitis A virus strains identified in jogaejeot associated with outbreaks in Seoul, South Korea

Jogaejeot, seasoned Venerupis philippinarum, is a traditional Korean fermented food, and hepatitis A virus (HAV) can be transmitted through contaminated food, especially bivalve shellfish, causing acute gastroenteritis worldwide. Here, we carried out a phylogenetic analysis to identify and characterize HAV strains in jogaejeot samples associated with hepatitis A (HA) outbreaks in Seoul, South Korea, in 2019. The HAV strains were identified using blast and molecular analysis of the amplified HAV VP1-P2B genome region. The HAV strains identified in the five jogaejeot samples shared at least 99% sequence identity, were all classified as genotype IA and were most closely related to strains that are widespread in East Asia. These results support a link between the consumption of jogaejeot and the HA outbreaks observed in 2019 in Seoul. In addition, they indicate a need for more stringent enforcement of food safety regulations for the shellfish industry, especially against HAV, and the value of widespread vaccination.

Hepatitis A Outbreak Among Men Who Have Sex With Men, Yokohama, Japan, January to May 2018

Between January and May in 2018, 17 male cases of hepatitis A were reported in Yokohama, Japan. Of these, 14 identified as men who have sex with men. The viral sequence in this outbreak was same as that of the recent European and Taiwanese outbreaks strain.

Molecular epidemiology of hepatitis A outbreaks in two districts in Indonesia in 2018: Same subtype, but different strains

The present study aimed to analyse molecular epidemiological data from hepatitis A virus (HAV) outbreaks in two affected areas. The association between the knowledge of hepatitis A and incidence of infection was also determined. Serum samples were obtained from 88 individuals with clinical manifestations of acute hepatitis in Lamongan (n=54) in January 2018 and Bangkalan (n=34) in March 2018. The outbreak investigation was started one day after the outbreaks were reported by the Public Health Offices in Lamongan and Bangkalan. Anti-HAV immunoglobulin M (IgM) and PCR amplification products of the VP1 capsid protein-P2A protease and VP1-VP3 junctions were analysed. Positive PCR products were sequenced, and a phylogenetic tree was constructed using Molecular Evolutionary Genetics Analysis X software. The control group comprised healthy students and staff members from the two affected areas. Thus, 172 responses from the control and hepatitis A case groups were analysed to assess the association between the students' knowledge level and the incidence of HAV infection. A total of 32 (59.25%) of the 54 individuals from Lamongan and 19 (55.9%) of the 34 participants from Bangkalan were positive for anti-HAV IgM; 26 PCR tests were positive in the VP3-VP1 and/or VP1-P2A junction, which were identified as HAV subgenotype IA. The subtype of HAV in the two areas was IA, similar to those identified previously, but the viruses did not originate from the same strain, as identified by multiple alignment. The knowledge level of the students and staff members in Lamongan studying and working at a half-day school exhibited a significant association with the incidence; however, no association was observed among the students in Bangkalan studying at a full-day school with a dormitory.

Characteristics of acute hepatitis A virus infection before and after 2001: A hospital-based study in Tokyo, Japan

BACKGROUND AND AIM

The incidence of acute hepatitis A [AH (A)] is decreasing because of improvements in hygiene; however, cases of sporadic severe hepatitis are still being reported. We assessed the epidemiology of AH (A) in Japan.

METHODS

This was a hospital-based retrospective study, in which 126 AH (A) patients (96 men [76%], median age 39 [range, 19-66] years) were enrolled. Patients diagnosed with AH (A) before 2001 (n = 79) and after 2001 (n = 47) were compared.

RESULTS

The incidence of AH (A) showed peaks in 1990, 1999, and 2018. After 2001, one patient had hepatitis B virus, four had human immunodeficiency virus, and three had syphilis coinfections. Before and after 2001, HAV was transmitted, respectively, by raw oysters (28% and 26%), overseas travel (19% and 28%), and sexual contact (0% and 19%) (P < 0.01). The frequencies of symptoms were appetite loss (51% and 32%), fever (63% and 81%), and diarrhea (3% and 13%) (all P < 0.05), respectively. On admission, the median levels of alanine aminotransferase (1455 and 3069 U/L) and γ-glutamyl transpeptidase (221 and 345 U/L) were significantly higher (P < 0.01), and the prothrombin time (77.5% and 65.9%) and platelet count (22.7 and 16.4 × 10/μL) were significantly lower after 2001 (P < 0.05). A time to normalization of the bilirubin level ≥ 30 days was associated with older age and a diagnosis of AH (A) after 2001.

CONCLUSIONS

Outbreaks and severe AH (A) cases due to sexual transmission have been reported recently. It is necessary to examine their sexual behavior and other sexual infection.

Hepatitis A virus-associated fulminant hepatitis with human immunodeficiency virus coinfection

Hepatitis A virus (HAV) commonly causes acute hepatitis in humans and is transmitted through the fecal-oral route or by ingestion of contaminated food or water. HAV infection generally follows a self-limiting course; it can seldom cause fulminant hepatitis that increases the risk of mortality. To the best of our knowledge, this is the first reported fatal case of fulminant hepatitis caused by HAV in a 40-year-old male with human immunodeficiency virus (HIV) infection. The HAV genotype in this case was IA, which has recently become common globally among people living with HIV (PLWHIV), intravenous drug users, and homeless people especially in developed countries. His HIV infection was stabilized by antiretroviral drugs and his CD4 values were stable. He developed acute hepatic encephalopathy, did not respond to repeated plasma exchange therapy, and died rapidly. It is known that HIV co-infection sometimes leads to fulminant non-HAV hepatitis, although evidence supporting a correlation between fulminant hepatitis A risk and HIV infection is still lacking. This case demonstrated the fatal risk of HAV infection in PLWHIV; it was suggested that education about appropriate preventive measures and vaccination are important for preventing HAV infections among PLWHIV.

Outbreak of hepatitis A linked to European outbreaks among men who have sex with men in Osaka, Japan, from March to July 2018

AIM

Ongoing hepatitis A outbreaks among men who have sex with men (MSM) have been reported worldwide, mainly in Europe, since 2016. In Japan, there has been an increase in the number of notified hepatitis A cases since January 2018, most of which were suspected to have been transmitted through homosexual contact. In this paper, we describe the current outbreak situation of hepatitis A among MSM.

METHODS

Between March and July 2018, 13 cases of hepatitis A were identified in our hospital. All cases were identified as MSM. Data on clinical and laboratory findings and therapies were collected from medical records. Serum or stool samples were obtained from 13 patients and subjected to sequence analysis.

RESULTS

Of all patients, 12 reported to have male-to-male homosexual contact within 7 weeks prior to symptom onset, and 6 visited sex-on-premises venues in the same area. Furthermore, 12 patients were infected with HIV and consequently received antiretroviral therapy with sustained viral suppression. Ten patients received pulsed methylprednisolone therapy. Plasma exchange was additionally carried out in one patient. All patients received inpatient hospital care and were discharged alive. Sequence information, which was available in all cases, showed that the hepatitis A virus strain was identical to the EuroPride strain (RIVM-HAV16-090).

CONCLUSIONS

Results of sequence analysis suggest that the ongoing hepatitis A outbreak among MSM in Japan is linked to the 2016 European outbreaks. A vaccination program is urgently required for high-risk populations to control this ongoing outbreak.

Full-genome characterization of the RIVM-HAV16-090-like hepatitis A virus strains recovered from Japanese men who have sex with men, with sporadic acute hepatitis A

AIM

The major transmission mode of hepatitis A virus (HAV) in Japan is the fecal-oral route by contaminated foods. In contrast, HAV infection is well documented as a sexually transmitted disease in Europe and North America. The present study was undertaken to determine the full-genome sequence of HAV and trace the transmission route of HAV in Japanese men who have sex with men (MSM).

METHODS

In 2018, we encountered three Japanese MSM with acute hepatitis A co-infected with HIV for 4-12 years. Serum samples obtained from these patients were used for HAV full-genome analyses.

RESULTS

Isolated HAV strains were segregated into subgenotype IA. The three HAV strains shared 100% identity within the 481-nucleotide partial sequence. The entire nucleotide sequence showed that the three strains were 99.97% similar to each other with only two nucleotide substitutions. At the amino acid level, the three strains differed from each other by only one or two amino acids. All three strains obtained in the present study were >99.6% identical to the 66 reported strains isolated from Taiwan and European countries during 2015-2017. In addition, these 66 strains include the RIVM-HAV16-090 (EuroPride) strain, which has been involved in HAV outbreaks among MSM worldwide.

CONCLUSIONS

We determined for the first time the full-genome sequence of HAV isolated from Japanese MSM with acute hepatitis A and found that the strains were identical to those from MSM worldwide. Thus, these HAV strains were imported to Japan from foreign countries through MSM.

Surveillance of Hepatitis Viruses in Several Small Islands of Japan by Ship: A Public Health Approach for Elimination of Hepatitis Viruses by 2030

Aim

In 1990, an epidemiological survey by ship in some Japanese islands revealed high prevalence of hepatitis viruses and human T cell leukemia virus (HTLV). A second prevalence study of these viruses were accomplished in 2018, 28 years after initial survey. Analysis of these studies provide insights about strategies of elimination of hepatitis viruses at remote areas.

Materials and methods

In 2018, prevalence of hepatitis A virus (HAV), hepatitis B virus (HBV), hepatitis C virus (HCV), and HTLV was checked in 305 subjects in the islands those covered in 1990's survey. Hepatitis A virus was checked by the presence of anti-HAV IgG in sera; HBV was affirmed when hepatitis B surface antigen (HBsAg) in sera. Hepatitis C virus infection was evaluated by the presence of antibody to HCV (anti-HCV) and infection with HTLV was estimated by immunoassay. The methodology of assessment of different hepatitis viruses were optimized on the basis of present scientific knowhow.

Results

In 1990, the prevalence of HAV (presence of anti-HAV), HBV (presence of HBsAg), HCV (positivity for anti-HCV), and HTLV was found in 79.3%, 11.1%, 2.2%, and 3.3% of apparently health subjects of the islands, respectively. The prevalence of HAV, HBV, HCV, and HTLV was 47.9%, 4.6%, 1.0%, and 3.0%, respectively, in 2018. A shift of age of infected persons tilted towards right as the days progressed.

Conclusion

The study indicates a scenario of elimination of hepatitis viruses in Japan as lower trends of prevalence of HAV, HBV, and HCV have been recorded in 2018 compared with 1990, mainly by preventive measures. The most notable finding is that there are almost no new case below the age of 40 years, indicating an effective containment measure against these viruses.

How to cite this article

Akao T, Onji M, Kawasaki K, et al. Surveillance of Hepatitis Viruses in Several Small Islands of Japan by Ship: A Public Health Approach for Elimination of Hepatitis Viruses by 2030. Euroasian J Hepato-Gastroenterol 2019;9(2):57–62.

A Cluster of Hepatitis A Infections Presumed to be Related to Asari Clams and Investigation of the Spread of Viral Contamination from Asari Clams

In a cluster of hepatitis A infections that occurred in Nagano Prefecture in 2017, hepatitis A virus (HAV) was detected in asari clams (reference food) and the patients' fecal samples. Initially, the asari clams were suspected to be the infection source. However, the exact infection route remained unknown because a patient who had not consumed an asari clam dish also developed the disease. Suspecting a secondary infection originating from the asari clams, we investigated the presence of HAV genomes in water used for washing and soaking the frozen asari clams and detected HAV in the soaking water. These results suggest that soaking water is a risk factor for secondary contamination because of the leakage of HAV accumulated in midgut gland of the asari clam. During the asari clam sand removal process, the water used to clean asari clams spread across a wide area in a concentric fashion, raising concerns that this process may aggravate contamination. In addition to HAV, diarrhea viruses, such as norovirus, have often been detected in bivalves, including asari clams. Thus, handling these foodstuffs requires adequate care.

Evolution of hepatitis A virus seroprevalence among HIV-positive adults in Taiwan

OBJECTIVES

The study aimed to describe the seroprevalence of hepatitis A virus (HAV) in HIV-positive adult patients in Taiwan between 2012 and 2016 and to examine the evolution of HAV seroprevalence between 2004-2007 and 2012-2016.

METHODS

Clinical information and data of anti-HAV antibody results were collected from 2,860 antiretroviral-naïve HIV-positive Taiwanese aged 18 years or older who initiated combination antiretroviral therapy at 11 hospitals around Taiwan between 2012 and 2016 (2012-2016 cohort). A multivariate logistic regression model was applied to identify independent variables associated with HAV seropositivity. Comparisons of HAV seroprevalences and associated clinical characteristics were made between this 2012-2016 cohort and a previous cohort of 1580 HIV-positive patients in 2004-2007 (2004-2007 cohort).

RESULTS

Of the 2,860 HIV-positive patients between 2012 and 2016, the overall HAV seropositivity rate was 21.2% (605/2860), which was independently associated with an older age (adjusted odds ratio [AOR], per 1-year increase, 1.13; 95% confidence interval [95% CI], 1.11-1.15) and co-infection with hepatitis B virus (AOR 1.44; 95% CI, 1.08-1.93). Residence in southern Taiwan (AOR 0.49; 95% CI, 0.34-0.72) was inversely associated with HAV seropositivity. The overall HAV seroprevalence in the 2012-2016 cohort was significantly lower than that in the 2004-2007 cohort (21.2% vs 60.9%, p<0.01). The decreases of HAV seropositivity rate were observed in nearly every age-matched group, which suggested the cohort effect on HAV seroepidemiology. However, among individuals aged 25 years or younger, the HAV seropositivity rate increased from 3.8% (2/52) in the 2004-2007 cohort to 8.5% (50/587) in the 2012-2016 cohort, with 95.4% (560/587) being MSM in this age group of the latter cohort.

CONCLUSIONS

HAV seroprevalence has decreased with time among HIV-positive adults in Taiwan. The cohort effect has increased the number of young HIV-positive patients that are susceptible to HAV infection in a country without nationwide childhood vaccination program against HAV.

Fatal acute hepatic failure in a family infected with the hepatitis A virus subgenotype IB: A case report

RATIONALE

Hepatitis A viral infection is a well-known cause of subclinical or acute self-limited hepatitis. Few cases of hepatitis A virus (HAV)-associated acute liver failure (ALF) have been reported in low HAV endemic countries annually.

PATIENTS CONCERNS

To investigate the possible factors that affected the severity of HAV infection, a family cluster infected with the HAV subgenotype IB strain, which is not common in Japan, was described.

DIAGNOSES

This family consisted of five members who all were infected with HAV.

INTERVENTIONS

Four of the five patients hospitalized except for an asymptomatic patient.

OUTCOMES

Two of the five patients, men in their 50s and 60s, developed ALF, and one patient died. Various host factors, including sex (male), age, and a high bilirubin level, may affect the outcomes. Based on viral factors, HAV RNA was higher in the fatal case compared with others, and it decreased within a short period of time. The similarity of the nucleotide sequences was 99.9% among the HAV isolates based on an entire genomic sequence. Deletions and/or insertions on the HAV protein-coding sequences that caused a frameshift were found in surviving cases but not in the fatal case.

LESSONS

The rapid clearance of increased HAV and the absence of defective HAV might be closely associated with the onset of liver failure.

Use of Pathogen-Specific Antibody Biomarkers to Estimate Waterborne Infections in Population-Based Settings

PURPOSE OF REVIEW

This review discusses the utility of pathogen-specific antibody biomarkers for improving estimates of the population burden of waterborne infections, assessing the fraction of infections that can be prevented by specific water treatments, and understanding transmission routes and the natural history and ecology of disease in different populations (including asymptomatic infection rates).

RECENT FINDINGS

We review recent literature on the application of pathogen-specific antibody response data to estimate incidence and prevalence of acute infections and their utility to assess the contributions of waterborne transmission pathways. Advantages and technical challenges associated with the use of serum versus minimally invasive salivary antibody biomarkers in cross-sectional and prospective surveys are discussed. We highlight recent advances and challenges and outline future directions for research, development, and application of antibody-based and other immunological biomarkers of waterborne infections.

Comparison of immunogenicity and persistence between inactivated hepatitis A vaccine Healive® and Havrix® among children: A 5-year follow-up study

BACKGROUND

Inactivated vaccines for hepatitis A virus (HAV) infection are widely used in China. Mass vaccination programs drive the need for data on long-term persistence of vaccine-induced protection.

METHODS

A prospective, randomized, open-label clinical trial was conducted to compare geometric mean concentrations (GMCs) and seroconversion rates (SRs) of anti-HAV antibody elicited by the inactivated vaccines Healive and Havrix for 5 y post immunization, in which 400 healthy children were randomly assigned in a 3:1 ratio to receive 2 doses of Healive or Havrix at 0 and 6 month. Anti-HAV antibody concentration was detected by microparticle enzyme immunoassay (MEIA) during the study. Furthermore, an attempt was made to predict persistence of protective immunogenicity by using a suitable statistical model.

RESULTS

The GMCs were significantly higher after vaccination with Healive than after Havrix as comparator vaccine at 1, 6, 7, 18, 30, 42, 54 and 66 month (P < 0.01) with the peak point at 7 month (3427.2 mIU/ml for Healive and 1441.9 mIU/ml for Comparator). Similarly significant differences of SRs were found between the 2 groups at 1 and 6 month (P < 0.01). Afterwards, the SRs of both groups reached 100% at 7 month and did not decline until 66 month(99.1% for Healive and 97.5% for Comparator). A linear mixed model with a change point at 18 month(Model 3) was found to be suitable to predict persistence of protective immunogenicity induced by vaccines. It was estimated that the duration of protection for Healive was at least 20 y with a lower limit of GMC 95% confidence interval (CI) no less than 20 mIU/mL.

CONCLUSIONS

Compared with Havrix, the new preservative-free inactivated hepatitis A vaccine (Healive) in 2 doses showed better persistence of antibody concentrations for 5 y after full-course immunization among children and the persistence of protective immunogenicity was estimated for at least 20 y.

Molecular analysis of hepatitis A virus strains obtained from patients with acute hepatitis A in Mongolia, 2004-2013

Despite the high endemicity of hepatitis A virus (HAV) in Mongolia, the genetic information on those HAV strains is limited. Serum samples obtained from 935 patients with acute hepatitis in Ulaanbaatar, Mongolia during 2004-2013 were tested for the presence of HAV RNA using reverse transcription-PCR with primers targeting the VP1-2B region (481 nucleotides, primer sequences at both ends excluded). Overall, 180 patients (19.3%) had detectable HAV RNA. These 180 isolates shared 94.6-100% identity and formed four phylogenetic clusters within subgenotype IA. One or three representative HAV isolates from each cluster exhibited 2.6-3.9% difference between clusters over the entire genome. Cluster 1 accounted for 65.0% of the total, followed by Cluster 2 (30.6%), Cluster 3 (3.3%), and Cluster 4 (1.1%). Clusters 1 and 2 were predominant throughout the observation period, whereas Cluster 3 was undetectable in 2009 and 2013 and Cluster 4 became undetectable after 2009. The Mongolian HAV isolates were closest to those of Chinese or Japanese origin (97.7-98.5% identities over the entire genome), suggesting the evolution from a common ancestor with those circulating in China and Japan. Further molecular epidemiological analyses of HAV infection are necessary to investigate the factors underlying the spread of HAV and to implement appropriate prevention measures in Mongolia.