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

Abstract

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The available HAV endemicity profiles in Southeast Asian countries, aside from Thailand, are limited and outdated, but suggest an endemicity shift in the region that is not fully documented yet.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.

Fig 1. PRISMA flow diagram.

Fig 2

Age Specific HAV Seroprevalence^Ɣ in Thailand in Different Regions and Years A) Surveys with National Representativeness 1999–2014 B) Surveys from Bangkok 1998–2007 C) Surveys across Different Provinces 2004 (Except Tak Province Ran in 2010). ^ƔNote: Seroprevalence measured by either detection of total HAV antibodies or specific IgG HAV in blood. Abbreviations: HAV, hepatitis A virus; IgG, immunoglobulin G.

Fig 3. Age specific trends in HAV Seroprevalence from ASEAN countries (1999–2020) (n = 10).

Note: The dotted line represents the 50% threshold to visually categorize HAV endemicity. Only latest information from Thailand is depicted intentionally. Abbreviations: ASEAN, Association of Southeast Asian nations; HAV, hepatitis A virus.

Fig 4. Risk of bias assessment (n = 22¥).

^¥Risk of bias was not assessed for reports or publications from official Ministries of Health websites and outbreak specific studies. Color coding: Per item result: green = Yes; red = No. Overall result: green, and amber dots correspond to low and medium risk of bias, respectively.

Fig 5. Plain language summary.