Seroprevalence and subtype distribution of hepatitis C virus among blood donors and intravenous drug users in northern/northeastern Thailand

The prevalence of antibodies against hepatitis C virus (HCV) and the distribution pattern of HCV subtypes were analyzed among healthy blood donors and intravenous drug users (IVDUs) in northern/northeastern Thailand. The prevalence of anti-HCV antibodies was 3.2% (26/820) among blood donors in Khon Kaen, while it was 90% (71/79) among IVDUs in Chiang Rai. HCV RNA was detected in all anti HCV-positive sera collected from blood donors and IVDUs tested, as determined by reverse transcription PCR analysis. Sequence analyses of amplified fragments of the HCV genome revealed that in Khon Kaen and Chiang Rai,Thailand, HCV-3a (50-60%) was the most common HCV subtype, followed by HCV- 1a, HCV-1b, and subtypes of clade 6, each at 10-20%.