Infection rate and spontaneous seroreversion of anti-hepatitis C virus during the natural course of hepatitis C virus infection in the general population.

BACKGROUND Hepatitis C virus (HCV) infection is common worldwide but there are different prevalence rates in different countries. Data on the incidence of HCV in the general population are scarce. Spontaneous viral clearance occurs in 10-25% of infected individuals after acute infection yet controversy exists regarding the frequency of spontaneous clearance during the natural course of HCV infection in the general population. AIMS Anti-HCV prevalence, HCV infection rate, and the kinetics of anti-HCV were studied in a cross section of the general population of central Italy. STUDY POPULATION AND METHODS Anti-HCV prevalence (EIA-3 Ortho, RIBA-3 Ortho Chiron) was estimated in 3884 randomly selected individuals. Infection rate and antibody kinetics were estimated in 2032 participants for whom a second blood sample was taken after a median follow up of seven years. HCV-RNA determination by polymerase chain reaction was performed on follow up sera. RESULTS The overall confirmed anti-HCV prevalence was 2.4%. Two participants seroconverted for anti-HCV, giving an overall infection rate of 1.4 cases per 10 000 person years (95% confidence interval 0.2-5.2 per 10 000 person years). Of the 36 individuals confirmed as anti-HCV positive at enrollment, seven (19.4%) showed complete seroreversion. Seven (87%) of the eight individuals with indeterminate results at enrollment were serologically non-reactive at the end of follow up. Of the 25 participants confirmed to be anti-HCV positive at both enrollment and follow up, 23 (92.0%) with stable serological profiles tested positive for HCV-RNA at the end of follow up. CONCLUSIONS There is still a permanent risk, although low, of HCV spread in the general population in an area of low level endemicity. In this setting, a wide spectrum of modifications of viral and antibody patterns can be observed in HCV infected patients.