title: Detection of hepatitis A virus RNA in serum during the window period of infection.
abstract: BACKGROUND
  Hepatitis A virus (HAV) infection is the leading cause of clinically apparent viral hepatitis in many parts of the world, including developed and developing countries. Only limited information is available regarding the seronegative viremic window that follows HAV infection, and no systematic search has been reported for HAV RNA positive, IgM anti-HAV negative serum samples during hepatitis A outbreaks.
  
  
  OBJECTIVE
  To determine the proportion of HAV infected individuals among (i) children who were tested negative for anti-HAV antibodies during hepatitis A outbreaks which occurred in a public school (n = 157) and a child care center (n = 38); (ii) subjects (n = 46) initially classified as acute non-A-C hepatitis patients after clinical examination and serological tests (sporadic cases).
  
  
  METHODS
  Reverse transcription (RT)-PCR was performed to detect the presence of HAV genome in serum samples collected from anti-HAV negative, susceptible subjects.
  
  
  RESULTS
  HAV RNA was detected in 19/157 (12%) and 5/38 (13%) anti-HAV negative children from the public school and child care center, respectively. Twelve (26%) out of the 46 acute hepatitis patients (sporadic cases) were also HAV RNA positive. From nine of these 12 patients, a second blood sample was obtained 18-34 days after the first one: all nine had seroconverted to IgM anti-HAV, and their serum transaminases had reached elevated levels (mean ALT, 418; mean AST, 241).
  
  
  CONCLUSIONS
  Detection of HAV RNA before IgM anti-HAV seroconversion may be used as an early diagnosis method during hepatitis A outbreaks. HAV RNA testing should also help to elucidate acute hepatitis cases of unknown etiology.
authors.affiliation: Department of Virology, Oswaldo Cruz Institute, Avenida Brasil 4365, 21045-900 Rio de Janeiro (RJ), Brazil.
authors.forename: V S
authors.initials: VS
authors.lastname: de Paula
authors.forename: L M
authors.initials: LM
authors.lastname: Villar
authors.forename: L M
authors.initials: LM
authors.lastname: Morais
authors.forename: L L
authors.initials: LL
authors.lastname: Lewis-Ximenez
authors.forename: C
authors.initials: C
authors.lastname: Niel
authors.forename: A M C
authors.initials: AM
authors.lastname: Gaspar
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002656:Child Day Care Centers; D002675:Child, Preschool; D004196:Disease Outbreaks; D005260:Female; D006506:Hepatitis A / Q000175:diagnosis* / Q000453:epidemiology / Q000821:virology*; D035922:Hepatitis A Antibodies / Q000097:blood; D030041:Hepatitis A virus / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood; D007223:Infant; D008297:Male; D008875:Middle Aged; D012367:RNA, Viral / Q000097:blood*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012574:Schools; D000637:Transaminases / Q000097:blood; D014766:Viremia
chemical_list: D035922:Hepatitis A Antibodies; D007075:Immunoglobulin M; D012367:RNA, Viral; D000637:Transaminases