In pursuit of control and elimination: update on hepatitis A and B epidemiology and prevention strategies

Seroprevalence and Shifting Endemicities of Hepatitis A Virus Infection in Two Different Geographical Areas in the Philippines

INTRODUCTION

Infection with hepatitis A virus (HAV) is often asymptomatic in young children, but most adolescents and adults will have symptoms ranging from nausea and tiredness to acute liver failure and even death. The risk of severe disease is higher in older adults and people with pre-existing liver disease. Immunization is recommended in regions with low HAV endemicity levels, i.e., where people get infected later in life. In the Philippines, recent epidemiologic data on HAV infection are lacking. The objective of this study was to assess age-specific seroprevalence and evaluate risk factors associated with HAV seropositivity.

METHODS

People from two geographic areas (urban and rural) were recruited/enrolled and stratified by age group. HAV-specific immunoglobulin G (IgG) antibodies were measured with a chemiluminescent microparticle immunoassay. Sociodemographic parameters, hepatitis medical history, disease knowledge, hygiene measures and sanitation were assessed via a purpose-made questionnaire. Age at midpoint of population immunity (AMPI) was estimated using Kaplan-Meier curves. Logistic regression analyses were carried out to determine factors that were statistically significantly associated (p < 0.05) with HAV seropositivity.

RESULTS

Overall, 1242 participants were included in the analysis; 250/602 (41.5%) participants from urban regions and 283/640 (44.2%) participants from rural regions tested positive for HAV IgG antibodies. AMPI was 35 and 37 years for the rural and urban region, respectively. Higher education was associated with lower HAV seropositivity prevalence ratios, while not living in the same region for the last 5 years, regularly consuming street food and lack of handwashing after defecation were associated with a higher likelihood of HAV seropositivity.

CONCLUSION

Results suggest that HAV endemicity is low in the Philippines. Factors associated with HAV seropositivity were traveling, consuming street food and lack of basic hygienic gestures. Immunization might be an option to protect vulnerable populations against severe hepatitis A disease.

Seroprevalence and incidence of hepatitis A in Southeast Asia: A systematic review

BACKGROUND

A previous review on hepatitis A virus (HAV) seroprevalence in 2005 categorized Southeast Asia as a low HAV endemicity region. In 2010, the World Health Organization modified this from low to low/medium endemicity, pointing out that these estimates were based on limited evidence. Since then, there has been no attempt to review HAV epidemiology from this region. We conducted a systematic review of literature to collect information on HAV incidence and seroprevalence in select countries in the Southeast Asian region, specifically, The Association of Southeast Asian Nations over the last 20 years.

METHODOLOGY

This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. From the relevant articles, we extracted data and conducted a risk of bias assessment of individual studies.

RESULTS

The search yielded 22 and 13 publications on HAV seroprevalence and incidence, respectively. Overall, our findings point to a very low HAV endemicity profile in Thailand and Singapore and evidence of a shift towards low HAV endemicity in Indonesia, Lao People's Democratic Republic, Malaysia, the Philippines, and Vietnam. Only Singapore, Thailand, Malaysia, and the Philippines have existing HAV disease surveillance and reported incidence rates below 1 per 100,000. Several outbreaks with varying magnitude documented in the region provide insights into the evolving epidemiology of HAV in the region. Risk of bias assessment of studies revealed that the individual studies were of low to medium risk.

CONCLUSIONS/SIGNIFICANCE

The available HAV endemicity profiles in Southeast Asian countries, aside from Thailand, are limited and outdated, but suggest an endemicity shift in the region that is not fully documented yet. These findings highlight the need to update information on HAV epidemiology through strengthening of disease surveillance mechanisms to confirm the shift in HAV endemicity in the region.

Hepatitis A Outbreak Characteristics: A Comparison of Regions with Different Vaccination Strategies, Spain 2010-2018

We compared the cumulative incidence and characteristics of hepatitis A outbreaks in two groups of Spanish autonomous regions according to whether a universal or risk group vaccination strategy was followed. Outbreaks between 2010 and 2018 were analyzed. The cumulative incidence rate of outbreaks was estimated and compared by estimating the rate ratio (RR). The characteristics of the outbreaks and those of the first cases were compared. Adjusted OR (aOR) were calculated using a multivariate logistic regression model. Outbreak incidence was 16.04 per million persons in regions with universal vaccination and 20.76 in those with risk-group vaccination (RR 0.77; 95%CI 0.62-0.94). Imported outbreaks accounted for 65% in regions with universal vaccination and 28.7% in regions with risk-group vaccination (aOR 3.88; 95%CI 2.13-7.09). Adolescents and young adults aged 15-44 years and men who have sex with men were less frequently the first case of the outbreak in regions with a universal vaccination strategy (aOR 0.54; 95%CI 0.32-0.92 and 0.23; 95%CI 0.07-0.82, respectively). The cumulative incidence rate of outbreaks was lower in regions with universal vaccination. In all regions, independently of the vaccination strategy, activities to vaccinate persons belonging to high-risk groups for infection should be emphasized.

Changes in seroprevalence of hepatitis A after the implementation of universal childhood vaccination in Shandong Province, China: A comparison between 2006 and 2014

OBJECTIVES

The hepatitis A vaccine (HepA) has been included in the national expanded program on immunization (EPI) in China since 2008. This study was performed to evaluate the change in dynamics of the seroepidemiology of hepatitis A virus (HAV) before and after the introduction of the program.

METHODS

The trends in seroepidemiology of anti-HAV antibodies were examined in Shandong Province, China, drawing on two population-based samples of persons aged 1-59 years, one obtained in the year 2006 (n = 6682) and the other in 2014 (n = 5095).

RESULTS

A dramatic increase in seroprevalence of anti-HAV antibodies from 30.76% (95% confidence interval (CI) 26.24-35.28%) to 77.46% (95% CI 74.04-80.87%) among children aged 1.5-7 years (born after HepA was recommended for routine childhood immunization), as well as an increase from 35.32% (95% CI 29.31-41.33%) to 66.69% (95% CI 55.59-77.80%) in subjects aged 8-14 years, was observed in 2014 when compared with 2006. By contrast, a decline in seroprevalence among subjects aged 15-29 years, as seen particularly in those 20-29 years of age, from 85.72% (95% CI 80.29-91.14%) to 69.24% (95% CI 62.02-76.45%), was found in this study. There was no statistically significant difference in seroprevalence between 2006 and 2014 among the subjects older than 30 years of age.

CONCLUSIONS

The national HepA routine immunization program has had a positive effect, leading to an increase in anti-HAV seroprevalence among children in Shandong Province, China. More attention should be paid to young adults in the province.

Challenges in Management of Hepatitis A Virus Epidemiological Transition in Mexico

Hepatitis A virus (HAV) is the most common cause of acute viral hepatitis worldwide. The virus is mainly transmitted via the fecaloral route and, the incidence of infection is closely related to low socioeconomic conditions and poor sanitation. Mexico, previously categorized an area of high endemicity for HAV infection, is undergoing epidemiological transition. However, a limited number of HAV-related scientific reports regarding to virus burden is available. According to the local government health agency (Secretarla de Salud, SSA in Spanish), from 1994 to 2017 a reduction in the incidence of hepatitis related to HAV has been reported. However, HAV is still the most common cause of viral hepatitis in the country, and the pediatric population is the most prone to be infected with this virus. The analysis of the SSA data reveals that most of the reported cases from 1994 to 2017 were found in highly industrialized states. This information contradicts the documented relationship between the highest prevalence of infection and the lowest socio-economic status, and supports the necessity of viral detection and notification of HAV cases. Moreover, in spite that four HAV vaccines are available in Mexico and universal vaccination has been shown to be beneficial in developing countries in terms of declining endemicity, HAV vaccination is not mandatory in Mexico. In this review, preventive strategies including appropriate diagnosis, vaccination and public health policies on the basis of the epidemiologic status of HAV in Mexico are discussed.