Moritz UG Kraemer 1 , * , Marianne E Sinka 1 , Kirsten A Duda 1 , Adrian QN Mylne 2 , Freya M Shearer 2 , Christopher M Barker 3 , Chester G Moore 4 , Roberta G Carvalho 5 , Giovanini E Coelho 5 , Wim Van Bortel 6 , Guy Hendrickx 7 , Francis Schaffner 7 , Iqbal RF Elyazar 8 , Hwa-Jen Teng 9 , Oliver J Brady 2 , Jane P Messina 1 , David M Pigott 1 , 2 , Thomas W Scott 10 , 11 , David L Smith 1 , 10 , 12 , GR William Wint 13 , Nick Golding 2 , Simon I Hay 2 , 10 , 14 , *
30 June 2015
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.
Mosquitoes spread many disease-causing viruses and parasites between people and other animals, including viral infections such as dengue and chikungunya. Both infections cause high fevers often accompanied with excruciating joint pain or other flu-like symptoms. Dengue and chikungunya have become growing public health problems over the last fifty years. Today about half of the world's population is at risk of dengue infection, while chikungunya outbreaks, which were previously limited to Africa and Asia, have recently been reported in the Caribbean, South America and Europe.
The dengue and chikungunya viruses are transmitted between people by two species of mosquitoes called Aedes aegypti and Ae. albopictus. Therefore it is important to work out where these mosquito species are found around the globe to identify the areas at risk. It is also important to predict where these species could become established if they were introduced, in order to identify areas that could become at risk in the future.
Kraemer et al. now provide updated predictions about the distribution of these two mosquito species around the globe. These predictions are based upon the most up-to-date data on the known locations of the species combined with information on environmental conditions across the globe. The updated maps show that these Aedes mosquitoes are now found across all continents, including North America and Europe.
Aedes albopictus mosquitoes in particular are rapidly expanding their territory around the globe. Kraemer et al. used their new maps to show that, unlike in the United States, many of the areas in Europe and China that could support this mosquito species do not yet appear to have been colonized.
These findings provide a map of the distribution of both species as it stands at the moment. Further work is now needed to better understand which factors are contributing to the rapid expansion of these mosquitoes' range and what might be done to control this spread.