The global distribution and burden of dengue

Abstract

The public health burden of dengue is unknown; here cartographic approaches are used to provide insight into the global, regional and national burden of dengue, with the finding that the global number of infections per year is around 390 million, more than three times the estimate of the World Health Organization. The mosquito-borne viral infection dengue is found in tropical and subtropical regions worldwide, predominantly in urban and semi-urban areas. The incidence of dengue is on the increase, but the current global distribution is poorly known. Simon Hay and colleagues have applied novel mapping techniques to an extensive evidence base of nearly 10,000 case records. The outcome is an estimate of around 390 million new infections per year, more than double the most recent estimate from the World Health Organization. Importantly, this work extends the mapping to provide global estimates of the symptomatic and asymptomatic dengue case burden, at 96 and 294 million, respectively. Dengue is a systemic viral infection transmitted between humans by Aedes mosquitoes1. For some patients, dengue is a life-threatening illness2. There are currently no licensed vaccines or specific therapeutics, and substantial vector control efforts have not stopped its rapid emergence and global spread3. The contemporary worldwide distribution of the risk of dengue virus infection4 and its public health burden are poorly known2,5. 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 Organization2. 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.