Transmission Network of Hepatitis C Virus Subtype 2a in Huazhou County, Shaanxi Province, China

Background In Shaanxi Province, Huazhou County is one of the five highest rates of HCV infection incidence and prevalence. Understanding its characteristics of HCV transmission patterns could help guide targeted preventative strategies. This study employed phylogenetic analysis and the construction of a molecular transmission network of HCV-infected people in Huazhou County, to describe the predominant strains of HCV and identify factors associated with onward transmission. Methods The whole blood samples were obtained from HCV RNA positive individuals for NS5B sequencing. A maximum-likelihood phylogenetic tree was constructed to determine HCV subgenotypes. Bayesian phylogenetic analysis was employed to estimate the evolutionary history. The transmission network based on maximum-likelihood phylogenetic tree and pairwise distance was constructed. Logistic regression was used to identify the factors associated with clustering in the transmission network. Results 61 HCV NS5B sequences were successfully amplified and sequenced. The 61 sequences were found to all belong to subtype 2a by maximum-likelihood phylogenetic analysis. Bayesian phylogenetic analysis showed that the majority of the subtype 2a have descended from the northwest of China with estimated dates of 8 to 20 years before sampling. A transmission network was constructed with a clustering rate of 26.2%. Multivariate logistic regression showed individuals with a history of blood transfusion and living at Shi Village, Huazhou County were associated with clustered in the transmission network. Conclusion HCV transmission in Huazhou County was predominant by subtype 2a. High risk of transmission was associated with HCV infections in residential Shi Village, Huazhou County and people with a history of blood transfusions. Prioritizing targeted interventions for these groups may help to prevent infections.