Review on the molecular epidemiology of sexually acquired hepatitis C virus infection in the Asia‐Pacific region

INTRODUCTION: Sexual acquisition has emerged as a transmission route for hepatitis C virus (HCV) of growing importance among human immunodeficiency virus (HIV)‐positive populations. In Western countries, HCV epidemics have been increasingly detected among men who have sex with men (MSM). This review describes the molecular epidemiology of sexually acquired HCV infection in the Asia‐Pacific region. METHODS: A systematic search was performed on PubMed in March 2019. Either abstract or full‐text of each publication in the search results was screened for eligibility. Studies from different countries/cities involving eligible cases, who acquired HCV sexually with identified subtype, were synthesized for the evaluation of molecular epidemiology in the Asia‐Pacific region. Two large‐scale systematic reviews on the genotype distribution of HCV at a population level and among PWID were used as references for comparison. RESULTS AND DISCUSSION: Overall, 13 full‐text articles with 549 subjects originating from nine countries/cities were reviewed. A total of five genotypes and 14 subtypes were identified, dominated by subtypes 1b (23.0%), 2a (19.1%) and 3a (29.5%). A majority of the infected cases occurred in HIV‐positive MSM. In some places, notably Hong Kong, India and Indonesia, the predominant subtype in sexually acquired HCV infection in MSM was different from that circulating in the general population. Shared transmission networks between people who inject drugs (PWID) and MSM were shown in Australia and New Zealand, whereas overlapping risk elicited from a small number of subjects existed in Tokyo, Taipei and Guangxi. MSM‐specific clusters were identified in Hong Kong, Taipei and Hubei. CONCLUSIONS: The distribution of sexually acquired HCV was sparsely scattered across countries/cities in the Asia‐Pacific region. The threat of overlapping risk differed by locations, whereas transnational outbreaks remained uncommon. The paucity of information has hindered progress with comprehensive assessment in the Asia‐Pacific region, where seroprevalence of HCV among HIV‐positive MSM was relatively high.