Transmission network of Hepatitis C virus subtype 2a in Huazhou County, Shaanxi Province, China.

BACKGROUND: Huazhou County has one of the highest rates of hepatitis C virus (HCV) infection incidence and prevalence in Shaanxi Province, northwest China. Understanding the characteristics of HCV transmission patterns in this area could help guide targeted prevention 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: Whole blood samples were obtained from HCV RNA-positive individuals for sequencing of the non-structural protein 5B region. A maximum-likelihood (ML) phylogenetic tree was constructed to determine HCV subgenotypes, and Bayesian phylogenetic analysis was employed to estimate the evolutionary history. The transmission network was constructed using the ML phylogenetic tree and pairwise distances. Logistic regression was used to identify factors associated with clustering in the transmission network. RESULTS: ML phylogenetic analysis confirmed that the 61 sequences analyzed in the study belonged to subtype 2a. Bayesian phylogenetic analysis showed that the majority of subtype 2a sequences originated in the northwest of China and had descended approximately 8 to 20 years before sampling. Overall, 26.2% of participant sequences were grouped into phylogenetic network clusters. Multivariate logistic regression showed that individuals who had a history of blood transfusions and were living in Shi Village, Huazhou County, were more likely to form clusters within the transmission network. CONCLUSION: HCV transmission in Huazhou County was predominantly associated with subtype 2a. Having a history of blood transfusions and living in residential Shi Village, Huazhou County, were factors associated with a high risk of HCV infection transmission. Prioritizing targeted interventions for these patient groups may help to prevent further infections.