Editing IPCC:AR6/WGII/Chapter-16 (section)

==== 16.2.3.7 Vector-Borne Diseases ====

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Vector-borne diseases constitute a large burden of infectious diseases worldwide and are highly sensitive to fluctuations of weather conditions including extreme events. Thus, both extreme rainfall and droughts have increased infections ( ''high confidence'' , see ‘Other societal impacts—Vector-borne diseases’, Table SM16.23). For example, in Sudan, anomalous high rainfall increased ''Anopheles'' mosquito breeding sites, leading to malaria outbreaks ( [[#Elsanousi--2018|Elsanousi et al., 2018]] ), while in Barbados and Brazil, drought conditions in urban areas have enhanced dengue incidence due to changes in water storage behaviour creating breeding sites for ''Aedes'' mosquitoes around human dwellings ( [[#Lowe--2018|Lowe et al., 2018]] ; [[#Lowe--2021|Lowe et al., 2021]] ) . In the Caribbean and Pacific Island nations, weather extremes, such as storms and flooding, have led to outbreaks of dengue due to disruption to water and sanitation services, leading to increased exposure to ''Aedes'' mosquito breeding sites ( [[#Descloux--2012|Descloux et al., 2012]] ; [[#Sharp--2014|Sharp et al., 2014]] ; [[#Uwishema--2021|Uwishema et al., 2021]] ). In South and Central America, and Asia, dengue incidence has been shown to be sensitive to variations in temperature and the monsoon season in addition to variations induced by urbanisation and population mobility ( ''high confidence'' [South and Central America] ''; medium confidence'' [Asia]; see ‘Other societal impacts—Vector-borne diseases’, Table SM16.23).

The attribution of changes in disease incidence to long-term climate change is often limited by relatively short reporting periods often only covering 10–15 years. Most studies then attribute trends in the occurrence of vector-borne diseases to the trends in climate across the same observational period and do not refer to an early ‘no climate change’ baseline climate. This means that they also capture trends induced by longerterm climate oscillations. Nevertheless, we list them in Table SM16.22 on ‘impact attribution’ to clearly distinguish them from the analysis of interannual fluctuations. The overall consistency of their findings across regions and time windows indicates that climate change is an important driver of the observed latitudinal or altitudinal range expansions of vector-borne diseases into previously colder areas ( ''medium'' to ''high confidence'' , see ‘Other societal impacts—Vector-borne diseases’, Table SM16.22). In highland areas of Africa and South America, epidemic outbreaks of malaria have become more frequent due to warming trends that allow ''Anopheles'' mosquitoes to persist at higher elevations ( [[#Pascual--2006|Pascual et al., 2006]] ; [[#Siraj--2014|Siraj et al., 2014]] ). In the USA, ticks that transmit Lyme disease have expanded their range northwards because of warmer temperatures ( ''high confidence'' ; [[#Kugeler--2015|Kugeler et al., 2015]] ; [[#McPherson--2017|McPherson et al., 2017]] ; [[#Lin--2019|Lin et al., 2019]] ; [[#Couper--2020|Couper et al., 2020]] ; see ‘Other societal impacts—Vector-borne diseases’, Table SM16.22). In Southern Europe, climate suitability for ''Aedes'' mosquitoes, which transmit dengue and chikungunya, and ''Culex'' mosquitoes, which transmit West Nile virus, has also increased and contributed to unprecedented outbreaks including the 2018 West Nile fever outbreak ( ''medium confidence'' , [[#Medlock--2013|Medlock et al., 2013]] ; [[#Paz--2013|Paz et al., 2013]] ; [[#Roiz--2015|Roiz et al., 2015]] ; ECDC, 2018, see ‘Other societal impacts—Vector-borne diseases’, Table SM16.22).

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