Abstract
BackgroundMaternal 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.MethodsWe 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.ResultsThe 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.ConclusionThis 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.
Highlights
Maternal dengue antibodies are considered to play a significant role in dengue pathogenesis among infants
Among new-borns, a 55.0% IgG seropositivity was detected, yielding 99.3% co-positivity for placental antibody transfer (Kappa = 0.96)
A previous history of dengue was reported by 100 pregnant women, yielding 88% for the positive predictive value (PPV)
Summary
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. Dengue is a vector-borne disease caused by four distinct serotypes (DENV1, 2, 3 and 4), and approximately 3 billion people live or travel in regions infested by Ae. aegypti mosquitoes, which are considered the main vector [1]. Dengue has been one of the most important public health issues in tropical and subtropical regions of the world due to the spread of the vector infestation in domestic environments and the potential of DENV infection to cause successive epidemics in highly urbanized settings [2]. Naive populations have a four-fold risk of becoming infected and developing a clinical disease in response to each circulating serotype. Potential safe vaccines are under Phase III preventive trials and still need to be tested at a large scale in different endemic settings
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