title: Prevalence and follow-up of occult HCV infection in an Italian population free of clinically detectable infectious liver disease.
abstract: BACKGROUND
  Occult hepatitis C virus infection (OCI) is a recently described phenomenon characterized by undetectable levels of HCV-RNA in serum/plasma by current laboratory assays, with identifiable levels in peripheral blood mononuclear cells (PBMCs) and/or liver tissue by molecular tests with enhanced sensitivity. Previous results from our group showed an OCI prevalence of 3.3% in a population unselected for hepatic disease. The present study aimed to evaluate OCI prevalence in a larger cohort of infectious liver disease-free (ILDF) subjects. Clinical follow-up of OCI subjects was performed to investigate the natural history of the infection.
  
  
  RESULTS
  439 subjects referred to a Turin Blood Bank for phlebotomy therapy were recruited. They included 314 ILDF subjects, 40 HCV-positive subjects and 85 HBV-positive subjects, of whom 7 were active HBV carriers. Six subjects (4/314 ILDF subjects [1.27%] and 2/7 active HBV carriers [28%]) were positive for HCV-RNA in PBMCs, but negative for serological and virological markers of HCV, indicating OCI. HCV genotypes were determined in the PBMCs of 3/6 OCI subjects two had type 1b; the other had type 2a/2c. OCI subjects were followed up for at least 2 years. After 12 months only one OCI persisted, showing a low HCV viral load (3.73×10(1) UI/ml). By the end of follow-up all OCI subjects were negative for HCV. No seroconversion, alteration of liver enzyme levels, or reduction of liver synthesis occurred during follow-up.
  
  
  CONCLUSIONS
  This study demonstrated the existence of OCI in ILDF subjects, and suggested a high OCI prevalence among active HBV carriers. Follow-up suggested that OCI could be transient, with a trend toward the decrease of HCV viral load to levels undetectable by conventional methods after 12-18 months. Confirmation studies with a longer follow-up period are needed for identification of the OCI clearance or recurrence rates, and to characterize the viruses involved.
authors.affiliation: Unit of Cancer Epidemiology, C.E.R.M.S., University of Turin, Turin, Italy. gilliotos.demarco@cpo.it
authors.forename: Laura
authors.initials: L
authors.lastname: De Marco
authors.forename: Paola
authors.initials: P
authors.lastname: Manzini
authors.forename: Morena
authors.initials: M
authors.lastname: Trevisan
authors.forename: Anna
authors.initials: A
authors.lastname: Gillio-Tos
authors.forename: Franca
authors.initials: F
authors.lastname: Danielle
authors.forename: Cinzia
authors.initials: C
authors.lastname: Balloco
authors.forename: Alessandra
authors.initials: A
authors.lastname: Pizzi
authors.forename: Eleonora
authors.initials: E
authors.lastname: De Filippo
authors.forename: Sergio
authors.initials: S
authors.lastname: D'Antico
authors.forename: Beatrice
authors.initials: B
authors.lastname: Violante
authors.forename: Adriano
authors.initials: A
authors.lastname: Valfrè
authors.forename: Franco
authors.initials: F
authors.lastname: Curti
authors.forename: Franco
authors.initials: F
authors.lastname: Merletti
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Richiardi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D016174:Hepacivirus / Q000472:pathogenicity*; D006526:Hepatitis C / Q000097:blood / Q000150:complications / Q000453:epidemiology*; D006801:Humans; D007558:Italy / Q000453:epidemiology; D007963:Leukocytes, Mononuclear / Q000821:virology; D008297:Male; D008875:Middle Aged; D012367:RNA, Viral / Q000097:blood
chemical_list: D012367:RNA, Viral