No abstract

An alarmingly high incidence of HCV re-infection was found in this group. This high re-infection rate indicates that current prevention measures should be discussed, frequent HCV RNA testing should be continued after successful treatment and, in case of possible relapse, clade typing should be performed to exclude re-infection.

Most new cases of hepatitis C virus (HCV) infections in the developed world are associated with injection drug use. However, treatment for people who inject drugs (PWID) is controversial, as successful treatment risks being followed by new infection. Reinfection after sustained virologic response has been reported, but is the risk so great that treatment should be withheld from this large HCV population? Preliminary evidence suggests that the reinfection incidence is low, but studies to date have been limited by small sample size and few cases of reinfection. In this review, we assess data from studies among PWID of HCV reinfection following treatment to give a reasonable estimate on how frequently reinfection appears and try to characterize those most at risk, The observation that spontaneous clearance of HCV reinfection following treatment occurs is suggestive of a partial protective immunity against persistent infection.

Since its initial identification in St. Petersburg, Russia, the recombinant hepatitis C virus (HCV) 2k/1b has been isolated from several countries throughout Eurasia. The 2k/1b strain is the only recombinant HCV to have spread widely, raising questions about the epidemiological background in which it first appeared. In order to further understand the circumstances by which HCV recombinants might be formed and spread, we estimated the date of the recombination event that generated the 2k/1b strain using a Bayesian phylogenetic approach. Our study incorporates newly isolated 2k/1b strains from Amsterdam, The Netherlands, and has employed a hierarchical Bayesian framework to combine information from different genomic regions. We estimate that 2k/1b originated sometime between 1923 and 1956, substantially before the first detection of the strain in 1999. The timescale and the geographic spread of 2k/1b suggest that it originated in the former Soviet Union at about the time that the world's first centralized national blood transfusion and storage service was being established. We also reconstructed the epidemic history of 2k/1b using coalescent theory-based methods, matching patterns previously reported for other epidemic HCV subtypes. This study demonstrates the practicality of jointly estimating dates of recombination from flanking regions of the breakpoint and further illustrates that rare genetic-exchange events can be particularly informative about the underlying epidemiological processes. Hepatitis C virus (HCV) infection presents a major global health burden, with the WHO estimating that 170 million chronic carriers are at risk of developing severe clinical outcomes such as cirrhosis and hepatic cellular carcinoma (56, 71). The virus belongs to the single-stranded positive-sense RNA virus family Flaviviridae and is characterized by considerable genetic diversity. HCV diversity is classified into six main genotypes (genotypes 1 to 6), each of which is further divided into numerous subtypes, and the virus exhibits nucleotide sequence divergences of 30 and 20% at the genotype and subtype levels, respectively (58). The high genomic heterogeneity of HCV is a result of both its high rate of evolution and its long-term association with human populations (60). Although there is no indication for a zoonotic virus reservoir, a related virus has recently been discovered in dogs (22).The greatest diversity of HCV is found in West and Central Africa and in Southeast Asia, where the virus appears to have persisted endemically for at least several centuries (49, 60). The current distribution of HCV genotypes and subtypes is geographically structured, reflecting differences in the rates and routes of transmission of the various subtypes and genotypes. Epidemic strains, exemplified by subtypes 1a, 1b, and 3a, are characterized by high prevalence, low genetic diversity, and a global distribution and are typically associated with transmission via infected blood products and injecting drug use (IDU) during the 20th century (13, 4...