title: Acute hepatitis C in a contemporary US cohort: modes of acquisition and factors influencing viral clearance.
abstract: BACKGROUND
  Acute hepatitis C virus (HCV) infection is often asymptomatic; thus, its epidemiology and natural history are difficult to define.
  
  
  METHODS
  Acute HCV infection was identified on the basis of HCV seroconversion within 1 year (n=45), new anti-HCV seropositivity with clinical acute hepatitis (n=21), or HCV strain sequencing after an iatrogenic exposure (n=1). Risk factors were assessed with a baseline questionnaire, and participants were followed up prospectively with serial measurement of viral loads.
  
  
  RESULTS
  Of 67 persons with acute HCV infection, most were asymptomatic (64%) and injection drug users (66%). Thirteen had an unknown mode of transmission; of these, 11 reported high-risk sexual behavior. Ten acquired acute HCV infection within 3 months of an iatrogenic exposure; 3 had confirmed iatrogenic infection, and 4 had no other risk factors identified. The spontaneous viral clearance rate after 6 months of infection was 18% (95% confidence interval, 11%-31%). The rate of viral clearance varied significantly by sex (34% vs. 3% for women vs. men; P<.001).
  
  
  CONCLUSIONS
  High-risk sexual or iatrogenic exposures may be important contemporary risk factors for HCV infection. The spontaneous viral clearance rate (18%) in this contemporary study was similar to that reported for past studies of transfusion-associated HCV infection. Women were more likely to clear acute HCV infection than men.
authors.affiliation: Department of Medicine, Division of Infectious Diseases, University of Washington, 325 Ninth Avenue, Seattle, WA 98104, USA. chiaw@u.washington.edu
authors.forename: Chia C
authors.initials: CC
authors.lastname: Wang
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Krantz
authors.forename: Jared
authors.initials: J
authors.lastname: Klarquist
authors.forename: Meighan
authors.initials: M
authors.lastname: Krows
authors.forename: Lanamarie
authors.initials: L
authors.lastname: McBride
authors.forename: Edward P
authors.initials: EP
authors.lastname: Scott
authors.forename: Thomas
authors.initials: T
authors.lastname: Shaw-Stiffel
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Weston
authors.forename: Hanne
authors.initials: H
authors.lastname: Thiede
authors.forename: Anna
authors.initials: A
authors.lastname: Wald
authors.forename: Hugo R
authors.initials: HR
authors.lastname: Rosen
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000914:Antibodies, Viral / Q000097:blood; D015331:Cohort Studies; D018562:Disease Transmission, Infectious; D005260:Female; D016174:Hepacivirus / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D006526:Hepatitis C / Q000097:blood / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control / Q000635:transmission*; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012367:RNA, Viral / Q000032:analysis; D012307:Risk Factors; D012737:Sex Factors; D012725:Sexual Behavior; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology; D019562:Viral Load; D014766:Viremia
chemical_list: D000914:Antibodies, Viral; D007075:Immunoglobulin M; D012367:RNA, Viral