Dengue Endemicity, Force of Infection, and Variation in Transmission Intensity in 13 Endemic Countries

Abstract

Dengue endemicity varies but comparative, multicountry data are extremely limited. An improved understanding is needed to prioritize prevention, including vaccination, which is currently recommended only under specific epidemiological conditions. We used serological study data from 46 geographical sites in 13 countries to estimate dengue force of infection (FOI, the proportion of children seroconverting per year) under assumptions of either age-constant or age-varying FOI, and the age at which 50% and 80% of children had been infected. After exclusions, 13 661 subjects were included. Estimated constant FOI varied widely, from 1.7% (Singapore) to 24.1% (the Philippines). In the site-level analysis 44 sites (96%) reached 50% seroconversion and 35 sites (75%) reached 80% seroconversion by age 18 years, with significant heterogeneity. These findings confirm that children living in dengue-endemic countries receive intense early dengue exposure, increasing risk of secondary infection, and imply serosurveys at fine spatial resolutions are needed to inform vaccination campaigns.

Keywords: dengue; endemicity; epidemiology; infectious disease transmission; seroprevalence; vaccines.

Figure 1.

Study flow chart.

Figure 2.

Observed seroprevalence by age (circles) and 95% confidence interval (CI), adjusted for clustering (spikes) and estimate seroprevalence assuming constant force of infection (FOI) (solid line) and 95% CIs (shaded area). Dotted lines correspond to estimated seroprevalence under an assumption of age-varying FOI.

Figure 3.

Age of 80% seroconversion by site, estimated from best-fitting constant (circles) or age-varying (diamonds) models. Symbol size corresponds to frequency weights. ≥19 signifies estimates were outside the range of our data.