Hepatitis C virus 3b strains in injection drug users in Guangdong Province, China, may have originated in Yunnan Province.

The distribution of hepatitis C virus (HCV) genotypes/subtypes varies among different populations. Here, we investigated HCV infection and its genotype distribution in injection drug users (IDUs) in Guangdong Province of China. A total of 318 IDUs from two prisons were recruited. The genotypes/subtypes of HCV in IDUs were determined by phylogenetic analysis using E1 and/or NS5B gene sequences. Our previous data on blood donors (BDs) with no history of drug use were used as control population data for comparison. Our results showed that the prevalence of HCV 3b (20.9% vs. 3.6%, P = 3.4E-9) and 6a (57.0% vs. 39.8%, P = 1.2E-5) was higher in IDUs than in BDs. In contrast, the prevalence of HCV 1b (43.4% vs. 5.6%, P = 9.8E-23) in BDs was higher than in IDUs. Phylogeographic analysis indicated that HCV 3b migrated from Yunnan to Guangdong Province and became endemic, with further transmission to other regions of China. The trend of HCV 3b dissemination in China in IDUs requires further attention, and a strategy for prevention and therapy is needed.