While most other vector-borne neglected tropical diseases are seldom fatal, they involve chronic infections that confer substantial disability. The estimated number of incident cases in 2017 was 209 million for malaria and 105 million for dengue 7. For West Nile virus, a wide range of bird species serve as reservoir hosts with a range of competence, whereas humans, horses and other mammals serve as dead-end hosts.Īmong vector-borne diseases, malaria is the major killer, causing an estimated 620,000 deaths in 2017 (most occurring in Africa), followed by dengue, with an estimated 40,500 deaths (most occurring in Asia) 6. For example, for Lyme disease, small mammals and birds serve as competent (reservoir) hosts (they are infected by the tick vector and they can infect ticks) deer and other large- and medium-sized mammals serve as incompetent hosts (they provide adult ticks with blood meals but do not become infected) and humans serve as dead-end hosts (they are infected by ticks but do not infect ticks). Humans serve as the primary host for some vector-borne diseases, including malaria, dengue, chikungunya and Zika virus disease, whereas other vector-borne diseases have more complex transmission dynamics, with both human and non-human hosts (Table 1). The impact of climate change on the incidence, transmission season duration and spread of vector-borne diseases represents a major threat 4. According to the authoritative Intergovernmental Panel on Climate Change (IPCC), “Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems” 3. If current greenhouse gas emission trends continue, the mean global temperature could increase by 4 to 5 ☌ above preindustrial levels by the end of the century 2, 3, which would result in dramatic intensification of the changes already observed. Both wet and dry regions, however, have experienced an increase in extreme precipitation events. Increased evaporation from warming has resulted in complex, region-specific changes in the hydrological cycle while there has been an increase in overall global precipitation, some areas have become wetter and others have become drier. Global warming has exhibited considerable heterogeneity, with greater warming over land than over the oceans, the greatest warming occurring in the Arctic, and evidence for greater warming in winter versus summer and in nighttime versus daytime. The impacts of a 1 ☌ rise have been profound, including a decrease in the number of cold days and nights, an increase in the number of warm days and nights, an increase in extreme heat events, decreased snow cover, and accelerating sea level rise. Finally, to address the adverse impacts of climate change, we call for urgent and rapid reductions in greenhouse gas emissions, as well as adaptation to ongoing climate change through intensification of vector-borne disease prevention and control efforts.Īnthropogenic greenhouse gas emissions have caused the mean global temperature to increase by 1 ☌ above preindustrial levels 1, 2. We highlight the symbiotic intersection of (1) observational studies that elucidate how meteorological variables affect the incidence, transmission-season duration and spread of vector-borne diseases and (2) scenario-based modeling of the effects of future climate change that can aid long-term planning for the prevention and control of vector-borne diseases. We emphasize how the presence of many non-climate drivers of vector-borne disease transmission makes it difficult to isolate the role of climate change. Here, we discuss how climate affects the transmission dynamics and geographic spread of vector-borne diseases and the impact our changing climate has had thus far. Put simply, vectors, which are ectotherms (that is, cold-blooded animals), do better in a warmer world. The rapid warming of the Earth, caused by anthropogenic greenhouse gas emissions, has profound long-term implications for the prevention and control of vector-borne diseases.
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