title: Viremic profiles in asymptomatic and symptomatic chikungunya fever: a blood transfusion threat?
abstract: BACKGROUND
  The presence of a chikungunya virus (CHIKV) outbreak could have an impact on transfusion safety when there are a large number of infected persons during an epidemic. Serosurveys have found that 3% to 28% of infected persons remain asymptomatic and are potential disseminators of transfusion-associated chikungunya. However, the viremic profiles of asymptomatic chikungunya patients, the major determinant of the transfusion risk, are unknown.
  
  
  METHODS
  Data on CHIKV viremic profiles were obtained from a case-control study carried out in a chikungunya-affected area during the 2009 epidemic in Songkhla, Thailand. CHIKV-infected individuals were classified based on a combination of the patient's history and clinical and laboratory findings.
  
  
  RESULTS
  There were 134 laboratory-proven CHIKV-infected cases, of whom 122 (91.0%) were symptomatic and 12 (9.0%) were asymptomatic. The viremic levels in the symptomatic infected individuals peaked on the first 3 days and lasted up to 8 days as defined by viral isolates. CHIKV genomic products were detected as late as Day 17 of illness. The viral loads observed in the symptomatic individuals (median, 5.6 × 10(5) plaque-forming units per milliliter [pfu/mL]; range, 1.3 × 10(1) -2.9 × 10(8) pfu/mL) were higher than but not significantly different from those observed in the viremic asymptomatic individuals (median, 3.4 × 10(3) pfu/mL; range, 8.4 × 10(1) -2.9 × 10(5) pfu/mL [p = 0.22, Wilcoxon test]).
  
  
  CONCLUSIONS
  CHIKV infection is highly symptomatic and is associated with high-titred viremia. The viremic levels in asymptomatic CHIKV-infected individuals were in the range known to be capable of transmitting the disease to experimental animals. Asymptomatic CHIKV viremia individuals could be potential disseminators of transfusion-associated chikungunya.
authors.affiliation: Department of Pathology and the Department of Medicine, Faculty of Medicine, Prince of Songkla University, Hat Yai, Songkhla, Thailand; Bureau of Epidemiology, Department of Disease Control, Ministry of Public Health, Nonthaburi, Thailand.
authors.forename: Hatsadee
authors.initials: H
authors.lastname: Appassakij
authors.forename: Paiwon
authors.initials: P
authors.lastname: Khuntikij
authors.forename: Marisa
authors.initials: M
authors.lastname: Kemapunmanus
authors.forename: Rochana
authors.initials: R
authors.lastname: Wutthanarungsan
authors.forename: Khachornsakdi
authors.initials: K
authors.lastname: Silpapojakul
mesh_terms: D018354:Alphavirus Infections / Q000097:blood / Q000453:epidemiology* / Q000635:transmission* / Q000821:virology; D000818:Animals; D058070:Asymptomatic Diseases / Q000453:epidemiology; D001803:Blood Transfusion / Q000706:statistics & numerical data; D016022:Case-Control Studies; D065632:Chikungunya Fever; D002646:Chikungunya virus / Q000276:immunology / Q000302:isolation & purification*; D002522:Chlorocebus aethiops; D005260:Female; D006801:Humans; D008297:Male; D012367:RNA, Viral / Q000235:genetics / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012307:Risk Factors; D012698:Serologic Tests; D065227:Transfusion Reaction; D014709:Vero Cells; D014766:Viremia / Q000097:blood / Q000453:epidemiology* / Q000821:virology
chemical_list: D012367:RNA, Viral