Genetic diversity of hepatitis B virus strains derived worldwide: genotypes, subgenotypes, and HBsAg subtypes.

Sequences of 234 complete genomes and 631 hepatitis B surface antigen genes were used to assess the worldwide diversity of hepatitis B virus (HBV). Apart from the described two subgenotypes each for A and F, also B, C, and D divided into four subgenotypes each in the analysis of complete genomes supported by significant bootstrap values. The subgenotypes of B and C differed in their geographical distribution, with B1 dominating in Japan, B2 in China and Vietnam, B3 confined to Indonesia, and B4 confined to Vietnam, all strains specifying subtype ayw1. Subgenotype C1 was common in Japan, Korea, and China; C2 in China, South-East Asia, and Bangladesh, and C3 in the Oceania comprising strains specifying adrq-, and C4 specifying ayw3 is encountered in Aborigines from Australia. This pattern of defined geographical distribution was less evident for D1-D4, where the subgenotypes were widely spread in Europe, Africa, and Asia, possibly due to their divergence having occurred a longer time ago than for genotypes B and C, with D4 being the first split and still the dominating subgenotype of D in the Oceania. The genetic diversity of HBV and the geographical distribution of its subgenotypes provide a tool to reconstruct the evolutionary history of HBV and may help to complement genetic data in the understanding of the evolution and past migrations of man.

Trends in residual risk of transfusion-transmitted viral infections in France between 1992 and 2000.

BACKGROUND: Monitoring trends in residual risks of transfusion-transmitted viral infections (HIV, HTLV, HBV, and HCV) is important to assess improvements in blood safety. In France, theses trends were analyzed between 1992 and 2000. STUDY DESIGN AND METHODS: As risk is predominantly associated with the window period, residual risks were estimated by multiplying incidence rates by the durations of the window periods. Incidence rates were calculated from the data collected by the blood transfusion centers belonging to the Transfusion-Transmissible Agents Working Group, which currently collects more than 50 percent of the 2.5 million blood samples donated each year in France. RESULTS: Trend analysis showed a significant decrease in residual risks for HCV (p = 0.01) and HBV (p < 0.001). Although residual risks decreased for HIV and HTLV, the trends were not significant. In 1998 through 2000, residual risks were estimated to be 1 in 470,000 donations for HBV, 1 in 860,000 for HCV, 1 in 1,370,000 for HIV, nil for HTLV, and 1 in 250,000 for the four viruses combined. CONCLUSIONS: In France, the current risk of a blood recipient becoming infected with a retrovirus or a hepatitis virus is extremely low. The implementation of NAT in July 2001 is predicted to reduce the residual risk to 1 in 2,700,000 donations for HIV and 1 in 8,300,000 for HCV.

Outbreak of hepatitis C virus infection in a hemodialysis unit: potential transmission by the hemodialysis machine?

OBJECTIVE: To identify the routes of transmission during an outbreak of infection with hepatitis C virus (HCV) genotype 2a/2c in a hemodialysis unit. DESIGN: A matched case-control study was conducted to identify risk factors for HCV seroconversion. Direct observation and staff interviews were conducted to assess infection control practices. Molecular methods were used in a comparison of HCV infecting isolates from the case-patients and from patients infected with the 2a/2c genotype before admission to the unit. SETTING: A hemodialysis unit treating an average of 90 patients. PATIENTS: A case-patient was defined as a patient receiving hemodialysis with a seroconversion for HCV genotype 2a/2c between January 1994 and July 1997 who had received dialysis in the unit during the 3 months before the onset of disease. For each case-patient, 3 control-patients were randomly selected among all susceptible patients treated in the unit during the presumed contamination period of the case-patient. RESULTS: HCV seroconversion was associated with the number of hemodialysis sessions undergone on a machine shared with (odds ratio [OR] per additional session, 1.3; 95% confidence interval [CI95], 0.9 to 1.8) or in the same room as (OR per additional session, 1.1; CI95, 1.0 to 1.2) a patient who was anti-HCV (genotype 2a/2c) positive. We observed several breaches in infection control procedures. Wetting of transducer protectors in the external pressure tubing sets with patient blood reflux was observed, leading to a potential contamination by blood of the pressure-sensing port of the machine, which is not accessible to routine disinfection. The molecular analysis of HCV infecting isolates identified among the case-patients revealed two groups of identical isolates similar to those of two patients infected before admission to the unit. CONCLUSIONS: The results suggest patient-to-patient transmission of HCV by breaches in infection control practices and possible contamination of the machine. No additional cases have occurred since the reinforcement of infection control procedures and the use of a second transducer protector.