title: Prevalence and incidence of dengue virus and antibody placental transfer during late pregnancy in central Brazil.
abstract: BACKGROUND
  Maternal dengue antibodies are considered to play a significant role in dengue pathogenesis among infants. Determining the transplacental specific antibody transfer is invaluable for establishing the optimal vaccination age among infants in endemic regions.
  
  
  METHODS
  We conducted a cross-sectional study among pairs of maternal and corresponding umbilical cord blood samples in public hospitals. The prevalence and incidence of dengue infection were determined in 505 pairs of pregnant women and neonates during a large outbreak (2009-2010) in central Brazil. The women were interviewed at late pregnancy to assess current or past symptoms of dengue. All parturients and their neonates were screened using Dengue IgG Indirect ELISA (Panbio) to assess previous dengue exposure. A semi-quantitative measurement of the IgG antibody expressed by the index ratio was calculated using optical density (OD) values according to the manufacturer's instructions. The studied population of parturients and their offspring was also screened for recent dengue infection by the Dengue IgM-capture ELISA (Panbio). Those participants with history of fever and two or more symptoms of dengue at least 10 days before the delivery were also tested for the dengue NS1 antigen using the Dengue Early ELISA (Panbio) and RT-PCR.
  
  
  RESULTS
  The mean maternal age was 25.8 (SD = 6.4), and 83.6% of deliveries were between 37 and 41 weeks. Approximately half of the 505 women and neonates were IgG-seropositive, yielding 99.3% co-positive mother-child frequency of antibody transfer (Kappa = 0.96). The incidence of dengue infection was 2.8% (95% CI 1.4-4.4%) among the women considering 14 IgM-positive results and one DENV2 detected by RT-PCR. The dengue NS1 antigen was undetectable in the matched pairs.
  
  
  CONCLUSIONS
  This study provides critical data on the prevalence of transplacental transferred maternal-infant anti-dengue antibodies and incidence of infection. The design of future vaccine trials should consider diverse regional epidemiological scenarios.
authors.affiliation: Secretaria de Estado da Saúde de Goiás, Laboratório de Saúde Pública (LACEN-GO), Av. Contorno, 3,556, Jd, Bela Vista, Goiânia, GO 74,853-120, Brazil. angelafarmaceutica@hotmail.com
authors.forename: Angela F L T
authors.initials: AF
authors.lastname: Argolo
authors.forename: Valéria C R
authors.initials: VC
authors.lastname: Féres
authors.forename: Lucimeire A
authors.initials: LA
authors.lastname: Silveira
authors.forename: Anna Carolina M
authors.initials: AC
authors.lastname: Oliveira
authors.forename: Luiz A
authors.initials: LA
authors.lastname: Pereira
authors.forename: João Bosco Siqueira
authors.initials: JB
authors.lastname: Júnior
authors.forename: Cynthia
authors.initials: C
authors.lastname: Braga
authors.forename: Celina M T
authors.initials: CM
authors.lastname: Martelli
mesh_terms: D000328:Adult; D000914:Antibodies, Viral / Q000097:blood*; D001938:Brazil / Q000453:epidemiology; D003430:Cross-Sectional Studies; D003715:Dengue / Q000453:epidemiology* / Q000276:immunology / Q000635:transmission; D003716:Dengue Virus / Q000302:isolation & purification*; D005260:Female; D005312:Fetal Blood / Q000737:chemistry / Q000821:virology; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D015994:Incidence; D007231:Infant, Newborn; D018445:Infectious Disease Transmission, Vertical / Q000706:statistics & numerical data*; D010920:Placenta / Q000276:immunology / Q000821:virology*; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology / Q000276:immunology / Q000821:virology*; D015995:Prevalence
chemical_list: D000914:Antibodies, Viral; D007074:Immunoglobulin G