Hepatitis B virus infection in the Lao PDR: A systematic review

IntroductionEven though hepatitis B is endemic in the Lao PDR, the understanding of the epidemiology of hepatitis B infection is incomplete. This article reviews the available literature about hepatitis B seroprevalence, risk factors and genotypes in the Lao population in order to provide an up- to date summary of the HBV epidemiology in the Lao PDR, identify knowledge gaps and provide public health recommendations. MethodsUsing PubMed/Medline and ScienceDirect, all studies reporting the prevalence of hepatitis B markers or genotype distribution in the Lao PDR published were systematically reviewed. ResultsThe 21 studies included focused on the general population, blood donors, women, children, health care workers and garment factory workers. The studies varied extensively in sample size, target population, methods, study location and time periods. The prevalence of the hepatitis B surface antigen (HBsAg) in blood donors was reported to be 8.7%-9.6% in 2003-2006. In the years 2011-2012, the reported HBsAg prevalence among women (including pregnant women) ranged from 0%-9.5% and among children aged 5-9 years from 1.7%-8.7%, depending on study location and age. The majority of strains characterized in Lao PDR belonged to genotypes B and C. ConclusionStudies displayed considerable heterogeneity in populations, design and laboratory methods. A high HBsAg prevalence was reported in adults including pregnant women. Low infant vaccination coverage and compromised vaccine immunogenicity were found. Only two studies focused on HBV in risk populations, emphasizing the need for further studies to characterize hepatitis B epidemiology in potentially vulnerable groups. Hepatitis B infection continues to represent a substantial public health threat in the Lao PDR and needs to be monitored to inform health authorities and to counteract over-burdening of the health care system. In order to end mother to child transmission, vaccination coverage with the hepatitis B birth dose should be increased.