Hepatitis A virus genotype and its correlation with the clinical outcome of acute hepatitis A in Korea: 2006-2008

Emerging hepatitis E virus compared with hepatitis A virus: A new sanitary challenge

Hepatitis A (HAV) and E (HEV) viruses are able to cause liver disease in humans. Among the five classical hepatotropic viruses, they are mainly transmitted via the fecal-oral route. Historically, many similarities have thus been described between them according to their incidence and their pathogenicity, especially in countries with poor sanitary conditions. However, recent advances have provided new insights, and the gap is widening between them. Indeed, while HAV infection incidence tends to decrease in developed countries along with public health improvement, HEV is currently considered as an underdiagnosed emerging pathogen. HEV autochthonous infections are increasingly observed and are mainly associated with zoonotic transmissions. Extra hepatic signs resulting in neurological or renal impairments have also been reported for HEV, as well as a chronic carrier state in immunocompromised patients, arguing in favor of differential pathogenesis between those two viruses. Recent molecular tools have allowed studies of viral genome variability and investigation of links between viral plasticity and clinical evolution. The identification of key functional mutations in viral genomes may improve the knowledge of their clinical impact and is analyzed in depth in the present review.

The effectiveness and limitation of the national childhood hepatitis A vaccination program in the Republic of Korea: Findings from the Korean National Health and Nutrition Examination Survey (KNHANES), 2015

Background

Vaccination for hepatitis A virus (HAV) has been implemented as one of the national vaccination programs despite the epidemiological transition of HAV in the Republic of Korea. While the national HAV vaccination program is largely associated with the shift of socioeconomic trend in the country, concerns have been raised on the effectiveness of the HAV immunization. The objective of this study was to examine the epidemiological trend of HAV and assess the effectiveness of the nationwide HAV vaccination policy based on a nationally representative sample of the Korean population collected in 2015.

Methods

We analyzed anti-HAV of 5,856 respondents aged ≥10 years collected from Korean National Health and Nutrition Examination Survey (KNHANES) data in 2015. We estimated age-adjusted anti-HAV prevalence by sociodemographic and other characteristics. We evaluated the factors associated with anti-HAV positivity among each age group (10–19, 20–29, 30–45 and over 45 years old).

Results

The prevalence of anti-HAV among adults aged ≥10 years was 72.5% (95% confidence interval, CI, 73.7–71.4) in 2015. The lowest age-specific prevalence was among adults aged 20–29 years with 11.9% (95% CI 9.3–15.1%). The prevalence of anti-HAV among those aged 10–14 and 15–19 years was 59.7% (95% CI 52.7–66.4) and 24.0% (95% CI 19.5–29.3), respectively. The prevalence of anti-HAV among adults aged between 30 and 44 years rapidly increased from below 20% to above 90%. The prevalence of anti-HAV among adults aged ≥45 years was 97.8% (95% CI 96.0–97.6). Factors significantly associated with anti-HAV positivity among those aged 10–19 years old were young age, higher house income and high influenza vaccination rate. Compared to the respondents aged 10–19 years (those who were subject to the national childhood vaccine recommendation), those aged 20–29 years (those who were not subject to the recommendation) had low adjusted odds ratio (OR, 0.52 95% CI 0.34–.81 P-value = 0.004) for anti-HAV positivity.

Conclusions

The age-adjusted anti-HAV prevalence showed a U-shaped association, implying the high dependence of anti-HAV prevalence on age and the epidemiological shift. The inclusion of the hepatitis A vaccine into the national immunization recommendation was effective shown by the increase of immunity in the general population. However, the vaccination rate was low in the low-income group. Young adults aged 20–39 years may benefit from inclusion in the HAV vaccination program due to the significantly low vaccination rate.

Current status and strategies for the control of viral hepatitis A in Korea

Hepatitis A virus is one of the most frequent causes of foodborne infection, which is closely associated with sanitary conditions and hygienic practices. The clinical spectrum of acute hepatitis A is wide, ranging from mild case without any noticeable symptoms to severe case with acute liver failure leading to mortality. The severity and outcome are highly correlated with age at infection. In developing countries, most people are infected in early childhood without significant symptom. Ironically, in area where sanitary condition has improved rapidly, adults who do not have immunity for viral hepatitis A (VH-A) in early childhood is accumulating. Adults without immunity are exposed to risks of symptomatic disease and large outbreaks in society. In Korea, where hygiene has improved rapidly, acute hepatitis A is a significant health burden that needs to be managed with nationwide health policy. The incidence of symptomatic VH-A has increased since 2000 and peaked in 2009. Korea has designated hepatitis A as a group 1 nationally notifiable infectious disease in 2001. Since 2001, mandatory surveillance system has been established to detect every single case of acute hepatitis A. Universal, nationwide vaccination program for newborns was introduced in 2015. In this review, we will present the current epidemiologic status of viral hepatitis A, and evaluate the effectiveness of the current nationwide strategies for the control of viral hepatitis A in Korea. Furthermore, we presented some action proposals that can help eliminate viral hepatitis A, which is a significant health burden in Korea.

Deep sequencing in the management of hepatitis virus infections

The hepatitis viruses represent a major public health problem worldwide. Procedures for characterization of the genomic composition of their populations, accurate diagnosis, identification of multiple infections, and information on inhibitor-escape mutants for treatment decisions are needed. Deep sequencing methodologies are extremely useful for these viruses since they replicate as complex and dynamic quasispecies swarms whose complexity and mutant composition are biologically relevant traits. Population complexity is a major challenge for disease prevention and control, but also an opportunity to distinguish among related but phenotypically distinct variants that might anticipate disease progression and treatment outcome. Detailed characterization of mutant spectra should permit choosing better treatment options, given the increasing number of new antiviral inhibitors available. In the present review we briefly summarize our experience on the use of deep sequencing for the management of hepatitis virus infections, particularly for hepatitis B and C viruses, and outline some possible new applications of deep sequencing for these important human pathogens.

Nationwide Seropositivity of Hepatitis A in Republic of Korea from 2005 to 2014, before and after the Outbreak Peak in 2009

Background/Aims

The epidemiologic shift of hepatitis A virus (HAV) infection in the South Korean population resulted in a peak outbreak of hepatitis in 2009. The aim of this study was to clarify the seropositivity of anti-HAV antibody (anti-HAV) and its demographic characteristics before and after the peak outbreak from 2005 to 2014.

Methods

This retrospective study analyzed the anti-HAV data of all individuals from 1,795 medical institutions referred to a major central laboratory from January 2005 through December 2014, as a sentineal tool for monitoring annual variation of anti-HAV positivity. The prevalence of anti-HAV was adjusted for age and area with the standard population based on the 2010 Census data.

Results

A total of 424,245 individuals were included in this study. The overall age-adjusted anti-HAV prevalence decreased from 65.6% in 2005 to 62.2% in 2014. During the 10-year period, the seroprevalence continuously decreased in persons aged 30 to 39 years (69.6% to 32.4%) and those aged 40 to 49 years (97.9% to 79.3%) due to the cohort effect. In contrast, it increased in persons aged 10 to 19 years (15.4% to 35.2%), while it was the lowest (8.7%) in 2010 before rebounding to 20.2% in 2014 in persons aged 20 to 29 years due to a vaccination effect.

Conclusion

Although the HAV vaccination rate increased, the anti-HAV seropositivity in South Korea decreased from 65.6% to 62.2% in this study population. In particular, the immunity of young adults was still low, and an outbreak of HAV is possible in the near future. Therefore, continuous monitoring and optimal preventive measures to prevent future outbreaks should be considered.

Clinical Features and Transmission Pattern of Hepatitis A: An Experience from a Hepatitis A Outbreak Caused by Two Cocirculating Genotypes in Sri Lanka

Sri Lanka is one of the intermediate-endemic areas for hepatitis A virus (HAV), and concerns exist about the increasing HAV-susceptible population. In fact, Sri Lanka recorded a large hepatitis outbreak, possibly hepatitis A, around the end of the Sri Lankan war. It included more than 14,000 patients consisting of local residents, internally displaced personnel, and military personnel in the main combat zone. The outbreak had slowed down by October 2009; however, acute viral hepatitis continued to occur sequentially among military personnel. We obtained clinical information and serum samples from 222 patients with acute hepatitis who visited the Military Hospital Anuradhapura between January and September 2010. Samples were subjected to laboratory testing including HAV-immunoglobulin M and genotyping. Most patients (98.2%) were confirmed as having hepatitis A belonging to two subgenotypes: IA and IIIA. We did not observe any differences in clinical or biochemical features among patients with subgenotypes IA and IIIA except for pale stools and upper abdominal discomfort. During the investigation period, we observed a serial outbreak caused by identical HAV strains with an interval in line with that of typical HAV incubation periods. Most patients in the first outbreak were found in the training center, and patients in the second outbreak were found in multiple places where soldiers were assigned after the training center. These findings indicate that a strain of HAV diffused from one place to another along with movement of infected persons among the HAV-susceptible population. HAV vaccination for high-risk groups, such as young soldiers, is necessary.

Hepatitis A: epidemiology in resource-poor countries

PURPOSE OF REVIEW

Transmission of hepatitis A virus (HAV) infection is primarily fecal-oral. Symptomatic hepatitis, severe disease, and death are more likely to occur when infection occurs at an older age. Improvements in socioeconomic and hygienic conditions have led to a change in its epidemiology worldwide.

RECENT FINDINGS

In the last two decades, improved hygiene in several resource-poor countries has led to reduced transmission of HAV, an increase in average age at infection, and, consequently, a paradoxical increase in morbidity and mortality because of hepatitis A. In Argentina, introduction of one dose (instead of the conventional two doses, to reduce costs) of inactivated HAV vaccine at 12-month age in a universal childhood immunization program during such 'epidemiologic transition' has markedly reduced the incidence of symptomatic hepatitis A, and of fulminant hepatitis and liver transplantation caused by HAV infection. The monetary value of medical and nonmedical benefits of this strategy outweighed the expenditure on vaccination. These excellent results were possibly contingent upon a high vaccination coverage.

SUMMARY

Resource-poor countries should closely monitor the epidemiology of HAV infection and periodically undertake cost-effectiveness analyses of HAV immunization strategies. This should allow timely identification of epidemiologic transition and introduction of preventive strategies before HAV infection becomes a public health problem.

Hepatitis A virus genotype distribution during a decade of universal vaccination of preadolescents

A universal vaccination program among preadolescents was implemented in Catalonia, Spain, during the period of 1999-2013 and its effectiveness has been clearly demonstrated by an overall significant attack rate reduction. However, reductions were not constant over time, and increases were again observed in 2002-2009 due to the occurrence of huge outbreaks. In the following years, in the absence of large outbreaks, the attack rate decreased again to very low levels. However, an increase of symptomatic cases in the <5 age group has recently been observed. This is an unexpected observation since children younger than 6 are mostly asymptomatic. Such a long vaccination campaign offers the opportunity to analyze not only the effectiveness of vaccination, but also the influence of the circulating genotypes on the incidence of hepatitis A among the different age groups. This study has revealed the emergence of genotype IC during a foodborne outbreak, the short-lived circulation of vaccine-escape variants isolated during an outbreak among the men-having-sex-with-men group, and the association of genotype IIIA with the increase of symptomatic cases among the very young. From a public health perspective, two conclusions may be drawn: vaccination is better at an early age, and the vaccination schedule must be complete and include all recommended vaccine doses.

Hepatitis A virus: host interactions, molecular epidemiology and evolution

Infection with hepatitis A virus (HAV) is the commonest viral cause of liver disease and presents an important public health problem worldwide. Several unique HAV properties and molecular mechanisms of its interaction with host were recently discovered and should aid in clarifying the pathogenesis of hepatitis A. Genetic characterization of HAV strains have resulted in the identification of different genotypes and subtypes, which exhibit a characteristic worldwide distribution. Shifts in HAV endemicity occurring in different parts of the world, introduction of genetically diverse strains from geographically distant regions, genotype displacement observed in some countries and population expansion detected in the last decades of the 20th century using phylogenetic analysis are important factors contributing to the complex dynamics of HAV infections worldwide. Strong selection pressures, some of which, like usage of deoptimized codons, are unique to HAV, limit genetic variability of the virus. Analysis of subgenomic regions has been proven useful for outbreak investigations. However, sharing short sequences among epidemiologically unrelated strains indicates that specific identification of HAV strains for molecular surveillance can be achieved only using whole-genome sequences. Here, we present up-to-date information on the HAV molecular epidemiology and evolution, and highlight the most relevant features of the HAV-host interactions.

Genotypic shift of the hepatitis A virus and its clinical impact on acute hepatitis A in Korea: a nationwide multicenter study

BACKGROUND

The genotypic shift of hepatitis A virus (HAV) and its correlation with clinical course has not been evaluated in acute hepatitis A (AHA).

METHODS

From June 2007 to May 2009, we prospectively enrolled 546 AHA patients. We performed a nested reverse transcriptase polymerase chain reaction (RT-PCR) using the serum samples in addition to phylogenetic analysis, then we compared patient clinical features.

RESULTS

Among 351 successfully genotyped patients, we found genotype IIIA in 178 patients (51%) and IA in 173 patients (49%). The sequences of genotype IA are identical to previously reported Korean genotype IA, and the new IIIA genotype is closely related to NOR24/Norway. We retrospectively analyzed 41 AHA samples collected from 2000 to 2006 and found that all of them were genotype IA. Patients with genotype IIIA showed significantly higher levels of aspartate aminotransferase, higher levels of alanine aminotransferase, and lower platelet counts than patients with genotype IA when comparing baseline laboratory data or peak/lowest laboratory data during the disease course. However, there were no differences in duration of hospital stay, incidence of cholestatic hepatitis, acute kidney injury, and acute liver failure, or mortality between them.

CONCLUSIONS

A genotypic shift of the HAV was identified in Korean AHA subjects, and genotype IIIA HAV has become endemic. Although there were significant differences in the biochemical responses of AHA between genotype IA and genotype IIIA patients, we did not detect any differences in clinical outcomes such as complications or mortality.

Hepatitis A outbreak associated with a revolving sushi bar in Chiba, Japan: Application of molecular epidemiology

AIM

  The number of hepatitis A cases in Japan as well as in other developed countries has been progressively decreasing during the last several years. There is no universal hepatitis A vaccination program in Japan, and a hepatitis A virus (HAV) epidemic in Japan is not unlikely. In 2011, a hepatitis A outbreak associated with a revolving sushi bar occurred in Chiba, Japan. We aimed to analyze this outbreak.

METHODS

  Twenty-seven patients associated with this outbreak were admitted to the National Hospital Organization Chiba Medical Center. Molecular epidemiologic investigations were conducted.

RESULTS

  Twenty-six of the 27 patients had gone to the same revolving sushi bar, and then clinical symptoms appeared. HAV RNA was detected by reverse transcription polymerase chain reaction in 23 of the 27 (85.1%) patients whose sera had tested positive for anti-HAV immunoglobulin M. All isolates from this outbreak were clustered within subgenotype IA, displaying 100% sequence homology with each other in 232 bp from all 23 patients. All isolates belong to the IA-1 sublineage, which is endemic to Japan.

CONCLUSION

  A revolving sushi bar was associated with a hepatitis A outbreak, and molecular epidemiological investigations proved useful.

Laboratory diagnosis of hepatitis A

The diagnostic gold standard for hepatitis A is the detection of anti-hepatitis A virus (HAV) IgM antibodies and the determination of total anti-HAV by enzyme immunoassay. However, detection of HAV RNA can be useful in the diagnosis of patients without specific antibodies for hepatitis A and for the monitoring of infection. Studies using real-time PCR have demonstrated that HAV RNA can be detected not only in feces, but also in serum and saliva samples earlier than detection of antibodies, and that viremia may be present for a much longer period than the convalescent phase of hepatitis A. Alternative samples have been proposed for diagnosis, epidemiological studies, investigation of outbreaks and selection of persons receptive to vaccination. Understanding the events of clinical course that take place during the hepatitis A infection may lead to more effective diagnosis.