title: Improving the diagnosis of acute hepatitis C virus infection with expanded viral load criteria.
abstract: BACKGROUND
  The diagnosis of acute hepatitis C virus (HCV) infection is imprecise because antibody testing does not differentiate between acute and chronic infection. Although virologic features, such as viral load fluctuations and low levels of viremia, have been noted to be characteristic of acute HCV infection, these parameters have not been used for diagnosis.
  
  
  METHODS
  We validated the use of these novel parameters (ie, viral load fluctuations >1 log and HCV RNA levels <100,000 IU/mL) in a cohort of acute HCV seroconverters. We then applied standard diagnostic criteria for acute HCV infection in a cohort of high-risk injection drug users entering prison with suspected acute HCV infection (n=37). We subsequently assessed whether these novel virologic parameters, measured serially over a 10-week period, could enhance the diagnosis of acute infection.
  
  
  RESULTS
  Low-level viremia and viral load fluctuations were highly prevalent in our cohort of acute seroconverters (81% and 86%, respectively), whereas low-level viremia occurred in only 13% of control patients with chronic infection. With use of standard criteria, 37 inmates received a diagnosis of acute HCV infection. Among the 35 patients with HCV RNA detectable at baseline, we found low-level viremia to be highly prevalent (n=27; 77%); among patients with a minimum of 2 HCV RNA samples, we demonstrated viral fluctuations in more than one-third (n=9; 36%).
  
  
  CONCLUSIONS
  The diagnosis of acute infection in HCV-seropositive patients is strengthened by the use of virologic parameters that are uncommon in chronic disease. Viral load fluctuations and low levels of HCV RNA should be incorporated into standard diagnostic criteria.
authors.affiliation: Lemuel Shattuck Hospital, Division of Infectious Diseases, 170 Morton St., Jamaica Plain, MA 02130, USA. bmcgovern@tuftsmedicalcenter.org
authors.forename: Barbara H
authors.initials: BH
authors.lastname: McGovern
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Birch
authors.forename: Melinda J
authors.initials: MJ
authors.lastname: Bowen
authors.forename: Laura L
authors.initials: LL
authors.lastname: Reyor
authors.forename: Ellen H
authors.initials: EH
authors.lastname: Nagami
authors.forename: Raymond T
authors.initials: RT
authors.lastname: Chung
authors.forename: Arthur Y
authors.initials: AY
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D016174:Hepacivirus / Q000302:isolation & purification*; D006526:Hepatitis C / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011329:Prisoners; D012367:RNA, Viral / Q000097:blood; D015819:Substance Abuse, Intravenous; D019562:Viral Load; D055815:Young Adult
chemical_list: D012367:RNA, Viral