The global distribution and burden of dengue

Abstract

Dengue is a systemic viral infection transmitted between humans by Aedes mosquitoes. For some patients, dengue is a life-threatening illness. There are currently no licensed vaccines or specific therapeutics, and substantial vector control efforts have not stopped its rapid emergence and global spread. The contemporary worldwide distribution of the risk of dengue virus infection and its public health burden are poorly known. Here we undertake an exhaustive assembly of known records of dengue occurrence worldwide, and use a formal modelling framework to map the global distribution of dengue risk. We then pair the resulting risk map with detailed longitudinal information from dengue cohort studies and population surfaces to infer the public health burden of dengue in 2010. We predict dengue to be ubiquitous throughout the tropics, with local spatial variations in risk influenced strongly by rainfall, temperature and the degree of urbanization. Using cartographic approaches, we estimate there to be 390 million (95% credible interval 284-528) dengue infections per year, of which 96 million (67-136) manifest apparently (any level of disease severity). This infection total is more than three times the dengue burden estimate of the World Health Organization. Stratification of our estimates by country allows comparison with national dengue reporting, after taking into account the probability of an apparent infection being formally reported. The most notable differences are discussed. These new risk maps and infection estimates provide novel insights into the global, regional and national public health burden imposed by dengue. We anticipate that they will provide a starting point for a wider discussion about the global impact of this disease and will help to guide improvements in disease control strategies using vaccine, drug and vector control methods, and in their economic evaluation.

Figure 1. Global estimates of total dengue infections

Comparison of previous estimates of total global dengue infections in individuals of all ages, 1985 to 2010: Halstead et al. 1988, Monath et al. 1994, Rodhain et al. 1996, Rigau-Perez et al. 1998, TDR/WHO. scientific working group 2006, Beatty et al. 2009, apparent infections from this study. Estimates are aligned to the year of estimate and, if not stated, aligned to the publication date. Red shading marks the credible interval of our current estimate, for comparison. Error bars from ref. 10 and ref. 16 replicated the confidence intervals provided in these publications.

Figure 2. Global evidence consensus, risk and burden of dengue in 2010

a, shows National and subnational evidence consensus on complete absence (green) through to complete presence (red) of dengue. b, shows the probability of dengue occurrence at 5km × 5km spatial resolution of the mean predicted map (area under the receiver operator curve of 0.81 (±0.02 SD, n = 336)) from 336 boosted regression tree models. Areas with a high probability of dengue occurrence are shown in red and areas with a low probability in green. c, shows a cartogram of the annual number of infections for all ages as a proportion of national or sub-national (China) geographical area.