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Clapham, Hannah E.,Rodriguez-Barraquer, Isabel,Azman, Andrew S.,Althouse, Benjamin M.,Salje, Henrik,Gibbons, Robert V.,Rothman, Alan L.,Jarman, Richard G.,Nisalak, Ananda,Thaisomboonsuk, Butsaya,Kalay Oxford University Press 2016 The Journal of Infectious Diseases Vol.213 No.9
<P>The immune response to dengue virus (DENV) infection is complex and not fully understood. Using longitudinal data from 181 children with dengue in Thailand who were followed for up to 3 years, we describe neutralizing antibody kinetics following symptomatic DENV infection. We observed that antibody titers varied by serotype, homotypic vs heterotypic responses, and primary versus postprimary infections. The rates of change in antibody titers over time varied between primary and postprimary responses. For primary infections, titers increased from convalescence to 6 months. By comparing homotypic and heterotypic antibody titers, we saw an increase in type specificity from convalescence to 6 months for primary DENV3 infections but not primary DENV1 infections. In postprimary cases, there was a decrease in titers from convalescence up until 6 months after infection. Beginning 1 year after both primary and postprimary infections, there was evidence of increasing antibody titers, with greater increases in children with lower titers, suggesting that antibody titers were boosted due to infection and that higher levels of neutralizing antibody may be more likely to confer a sterilizing immune response. These findings may help to model virus transmission dynamics and provide baseline data to support the development of vaccines and therapeutics.</P>
Salje, Henrik,Cauchemez, Simon,Alera, Maria Theresa,Rodriguez-Barraquer, Isabel,Thaisomboonsuk, Butsaya,Srikiatkhachorn, Anon,Lago, Catherine B.,Villa, Daisy,Klungthong, Chonticha,Tac-An, Ilya A.,Fern Oxford University Press 2016 The Journal of Infectious Diseases Vol.213 No.4
<P>Proper understanding of the long-term epidemiology of chikungunya has been hampered by poor surveillance. Outbreak years are unpredictable and cases often misdiagnosed. Here we analyzed age-specific data from 2 serological studies (from 1973 and 2012) in Cebu, Philippines, to reconstruct both the annual probability of infection and population-level immunity over a 60-year period (1952–2012). We also explored whether seroconversions during 2012–2013 were spatially clustered. Our models identified 4 discrete outbreaks separated by an average delay of 17 years. On average, 23% (95% confidence interval [CI], 16%–37%) of the susceptible population was infected per outbreak, with >50% of the entire population remaining susceptible at any point. Participants who seroconverted during 2012–2013 were clustered at distances of <230 m, suggesting focal transmission. Large-scale outbreaks of chikungunya did not result in sustained multiyear transmission. Nevertheless, we estimate that >350 000 infections were missed by surveillance systems. Serological studies could supplement surveillance to provide important insights on pathogen circulation.</P>
Reconstruction of antibody dynamics and infection histories to evaluate dengue risk
Salje, Henrik,Cummings, Derek A. T.,Rodriguez-Barraquer, Isabel,Katzelnick, Leah C.,Lessler, Justin,Klungthong, Chonticha,Thaisomboonsuk, Butsaya,Nisalak, Ananda,Weg, Alden,Ellison, Damon,Macareo, Lou Nature Publishing Group UK 2018 Nature Vol.557 No.7707
<P>As with many pathogens, most dengue infections are subclinical and therefore unobserved(1). Coupled with limited understanding of the dynamic behaviour of potential serological markers of infection, this observational problem has wide-ranging implications, including hampering our understanding of individual-and population-level correlates of infection and disease risk and how these change over time, between assay interpretations and with cohort design. Here we develop a framework that simultaneously characterizes antibody dynamics and identifies subclinical infections via Bayesian augmentation from detailed cohort data (3,451 individuals with blood draws every 91 days, 143,548 haemagglutination inhibition assay titre measurements)(2,3). We identify 1,149 infections (95% confidence interval, 1,135-1,163) that were not detected by active surveillance and estimate that 65% of infections are subclinical. After infection, individuals develop a stable set point antibody load after one year that places them within or outside a risk window. Individuals with pre-existing titres of <= 1: 40 develop haemorrhagic fever 7.4 (95% confidence interval, 2.5-8.2) times more often than naive individuals compared to 0.0 times for individuals with titres > 1: 40 (95% confidence interval: 0.0-1.3). Plaque reduction neutralization test titres <= 1: 100 were similarly associated with severe disease. Across the population, variability in the size of epidemics results in large-scale temporal changes in infection and disease risk that correlate poorly with age.</P>