title: Secondary dengue virus infections during the 2009 outbreak in Buenos Aires.
abstract: OBJECTIVE
  To evaluate the occurrence of secondary dengue virus (DENV) infections during the 2009 outbreak in a non-endemic area. Viral loads were evaluated in serum from acute-phase patients, comparing primary and secondary infection.
  
  
  METHODS
  Serum samples from patients with clinical diagnosis of suspected dengue were referred to the Virology Laboratory at 'Ricardo Gutiérrez' Children's Hospital. Dengue-positive samples were classified as primary or secondary DENV infections through serological methods (anti-DENV IgM and IgG). Viral loads were measured by quantitative real-time PCR (qRT-PCR) in samples obtained in the first 5 days of infection. Statistical analyses were performed to evaluate factors that might correlate with differences in the viral load of primary or secondary infection.
  
  
  RESULTS
  A total of 229 DENV cases were confirmed; among them, 22.7% were secondary infections. No significant differences were found between the viral load of primary and secondary infections.
  
  
  CONCLUSIONS
  We detected a high percentage of secondary DENV infections in a non-endemic area; this finding might correspond to socio-demographic characteristics of the group under study or indicate a previous cryptic DENV circulation causing inapparent infections.
authors.affiliation: Laboratorio de Virología Hospital de Niños 'Ricardo Gutiérrez', Buenos Aires, Argentina.|Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina.
authors.forename: E
authors.initials: E
authors.lastname: Tittarelli
authors.affiliation: Laboratorio de Virología Hospital de Niños 'Ricardo Gutiérrez', Buenos Aires, Argentina.|Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina.
authors.forename: P R
authors.initials: PR
authors.lastname: Barrero
authors.affiliation: Laboratorio de Virología Hospital de Niños 'Ricardo Gutiérrez', Buenos Aires, Argentina.|Comisión de Investigaciones Científicas de la Provincia de Buenos Aires, Buenos Aires, Argentina.
authors.forename: A S
authors.initials: AS
authors.lastname: Mistchenko
authors.affiliation: Laboratorio de Virología Hospital de Niños 'Ricardo Gutiérrez', Buenos Aires, Argentina.|Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina.
authors.forename: L E
authors.initials: LE
authors.lastname: Valinotto
keywords: Virus Dengue; carga viral; charge virale; dengue virus; infección secundaria; infection secondaire; secondary infections; viral load