The global distribution of the arbovirus vectors Aedes aegypti and Ae. albopictus

Abstract

Dengue and chikungunya are increasing global public health concerns due to their rapid geographical spread and increasing disease burden. Knowledge of the contemporary distribution of their shared vectors, Aedes aegypti and Aedes albopictus remains incomplete and is complicated by an ongoing range expansion fuelled by increased global trade and travel. Mapping the global distribution of these vectors and the geographical determinants of their ranges is essential for public health planning. Here we compile the largest contemporary database for both species and pair it with relevant environmental variables predicting their global distribution. We show Aedes distributions to be the widest ever recorded; now extensive in all continents, including North America and Europe. These maps will help define the spatial limits of current autochthonous transmission of dengue and chikungunya viruses. It is only with this kind of rigorous entomological baseline that we can hope to project future health impacts of these viruses.DOI: http://dx.doi.org/10.7554/eLife.08347.001

Model-based projections of Zika virus infections in childbearing women in the Americas

“…Because temperature values were available for each location on a monthly basis, we computed monthly values of R 0 for each location and then used the mean of the highest six monthly values of R 0 as a singular estimate of R 0 for each location. This approach was broadly consistent with the way in which a temperature suitability index was used to inform mosquito occurrence probabilities by Kraemer and co-authors 7 .…”

“…More specifically, a boosted regression tree model was applied using a comprehensive set of known occurrences (n = 19,930) of Ae. aegypti and a set of environmental predictors known to influence the distribution of the species 7 . Covariates included a temperature suitability index 17 , contemporary mean and range maps of the Enhanced Vegetation Index and precipitation 34 , and an urbanization index from the Global Rural Urban Mapping Project.…”

“…Covariates included a temperature suitability index 17 , contemporary mean and range maps of the Enhanced Vegetation Index and precipitation 34 , and an urbanization index from the Global Rural Urban Mapping Project. We used a set of 100 spatial layers sampled from the posterior distribution estimated by Kraemer et al 7 Economic index. To account for socio-economic differences among populations residing in different regions, we used one-degree-resolution gridded estimates of purchasing power parity (PPP) in US$ from 2005 adjusted for inflation (G-Econ) 28 .…”

“…This declaration acknowledges the high potential for Zika to establish across the Americas given that its dominant vector, the Aedes aegypti mosquito, is endophilic and occupies an exceptionally broad geographical range 7 . Concern underlying this rare WHO declaration also stems from an association between Zika virus infection in pregnant women and a range of adverse fetal outcomes 2 , most notably congenital microcephaly 1 .…”

“…In conclusion, our model-based approach offers a unique way to leverage a variety of spatially detailed data products 7,14,27,28 to make a priori projections of attack rates and infections that could be experienced in the first wave of the ongoing Zika epidemic. Projections such as these have an important role to play in the early stages of an epidemic, when planning for surveillance and outbreak response is actively under way both internationally and locally 9 .…”