title: Anti-HCV IgG avidity index in acute hepatitis C.
abstract: BACKGROUND
  The diagnosis of acute hepatitis C (AHC) is based on seroconversion to positive anti-HCV, which is usually not clinically possible.
  
  
  OBJECTIVE
  To determine if avidity of anti-HCV IgG can be used for the diagnosis of AHC infection.
  
  
  METHODS
  We enrolled 40 consecutive patients with AHC, 16 drug addicts (IVDA) with exacerbation of chronic hepatitis C (IVDA e-CHC group), 21 non-IVDA with exacerbation of chronic hepatitis C (IVDA-free e-CHC group) and 40 with chronic hepatitis C (CHC group). HCV avidity index (HCV-AI) was determined by ELISA on sera pre-diluted 1:10 with 1M guanidine.
  
  
  RESULTS
  On admission, HCV-AI values were significantly lower in the AHC group (mean+/-S.D.: 0.50+/-0.30) than in IVDA-free e-CHC group (0.97+/-0.08, p<0.0001), IVDA e-CHC group (0.90+/-0.29, p<0.0001) or CHC group (1.06+/-0.20, p<0.0001). An HCV-AI lower than 0.7 obtained within the 8th day of illness distinguished patients with AHC infection from the IVDA-free e-CHC cases. An increase in HCV-AI was observed in 24 (72.7%) of 33 in AHC group, in none of 13 in IVDA-free e-CHC group and in 3 (27.3%) of 11 in IVDA e-CHC group.
  
  
  CONCLUSIONS
  HCV-AI is useful in identifying AHC infection in patients observed within the 8th day from the onset of symptoms.
authors.affiliation: Department of Public Medicine, Section of Infectious Diseases, Second University of Naples, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Coppola
authors.forename: Raffaella
authors.initials: R
authors.lastname: Pisapia
authors.forename: Cecilia
authors.initials: C
authors.lastname: Marrocco
authors.forename: Salvatore
authors.initials: S
authors.lastname: Martini
authors.forename: Luisa Maria
authors.initials: LM
authors.lastname: Vatiero
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Messina
authors.forename: Gilda
authors.initials: G
authors.lastname: Tonziello
authors.forename: Caterina
authors.initials: C
authors.lastname: Sagnelli
authors.forename: Pietro
authors.initials: P
authors.lastname: Filippini
authors.forename: Felice
authors.initials: F
authors.lastname: Piccinino
authors.forename: Evangelista
authors.initials: E
authors.lastname: Sagnelli
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006526:Hepatitis C / Q000097:blood / Q000175:diagnosis*; D018937:Hepatitis C Antibodies / Q000097:blood / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D018937:Hepatitis C Antibodies; D007074:Immunoglobulin G