Global risk mapping for major diseases transmitted by Aedes aegypti and Aedes albopictus

Abstract

Objectives: The objective of this study was to map the global risk of the major arboviral diseases transmitted by Aedes aegypti and Aedes albopictus by identifying areas where the diseases are reported, either through active transmission or travel-related outbreaks, as well as areas where the diseases are not currently reported but are nonetheless suitable for the vector.

Methods: Data relating to five arboviral diseases (Zika, dengue fever, chikungunya, yellow fever, and Rift Valley fever (RVF)) were extracted from some of the largest contemporary databases and paired with data on the known distribution of their vectors, A. aegypti and A. albopictus. The disease occurrence data for the selected diseases were compiled from literature dating as far back as 1952 to as recent as 2017. The resulting datasets were aggregated at the country level, except in the case of the USA, where state-level data were used. Spatial analysis was used to process the data and to develop risk maps.

Results: Out of the 250 countries/territories considered, 215 (86%) are potentially suitable for the survival and establishment of A. aegypti and/or A. albopictus. A. albopictus has suitability foci in 197 countries/territories, while there are 188 that are suitable for A. aegypti. There is considerable variation in the suitability range among countries/territories, but many of the tropical regions of the world provide high suitability over extensive areas. Globally, 146 (58.4%) countries/territories reported at least one arboviral disease, while 123 (49.2%) reported more than one of the above diseases. The overall numbers of countries/territories reporting autochthonous vector-borne occurrences of Zika, dengue, chikungunya, yellow fever, and RVF, were 85, 111, 106, 43, and 39, respectively.

Conclusions: With 215 countries/territories potentially suitable for the most important arboviral disease vectors and more than half of these reporting cases, arboviral diseases are indeed a global public health threat. The increasing proportion of reports that include multiple arboviral diseases highlights the expanding range of their common transmission vectors. The shared features of these arboviral diseases should motivate efforts to combine interventions against these diseases.

Keywords: Aedes aegypti; Aedes albopictus; Arboviral diseases; Chikungunya; Dengue; RVF; Yellow fever; Zika.

Conflict of interest statement

Conflict of interest

We declare no competing interests.

Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Figures

Figure 1

Global predicted habitat suitability of Aedes aegypti and Aedes albopictus.

Figure 2

Country-level suitability range for Aedes aegypti and/or Aedes albopictus: suitability ranges from 0 (white) to 100% (deep red). The percentage suitability was computed based on all grid cells that manifested suitability levels higher than 0.5.

Figure 3

Global country-level occurrences of the selected arboviral diseases. The map depicts the occurrences of selected arboviral diseases from no occurrence, shown in white, to the occurrence of all of the selected arboviral diseases, shown in red.

Figure 4

Global Zika fever occurrence. The global distribution of Zika fever corresponds well with the global Zika risk. Discrepancies are apparent in Sub-Saharan Africa, where there is a high risk of Zika fever but few occurrence reports. It is emphasized that displaying occurrences at the country level overstates the distribution of the virus, especially in countries such as Argentina and Chile.

Figure 5

Global dengue fever occurrence. The global distribution of dengue fever corresponds well with the global dengue risk. The distribution of dengue fever extends to the temperate part of the world, with some European countries reporting its occurrence. It is emphasized that displaying occurrences at the country level overstates the distribution of the virus, especially in China, Argentina, and Chile.

Figure 6

Global yellow fever occurrence. There are discrepancies between the global yellow fever risk and yellow fever occurrence. The discrepancies are apparent in the southern USA, Mexico, Caribbean countries, Southern Africa, Southern Europe, the Indian subcontinent, and Southeast Asian countries, as well as Oceania. It is emphasized that displaying occurrences at the country level overstates the distribution of the virus in Argentina.

Figure 7

Global chikungunya fever occurrence. The global distribution of chikungunya fever corresponds well with the global chikungunya risk, with minor discrepancies in countries of Sub-Saharan Africa. The distribution of chikungunya fever extends to the temperate part of the world, with some European countries reporting its occurrence. It is emphasized that displaying occurrences at the country level overstates the distribution of the virus in Argentina.

Figure 8

Global Rift Valley fever (RVF) occurrence. There are discrepancies between the global RVF risk and RVF occurrence. The discrepancies are apparent in all regional blocks except Africa.