8.2.8.1 Dengue

Dengue is the world’s most important vector-borne viral disease. Several studies have reported associations between spatial (Hales et al., 2002), temporal (Hales et al., 1999; Corwin et al., 2001; Gagnon et al., 2001) or spatiotemporal patterns of dengue and climate (Hales et al., 1999; Corwin et al., 2001; Gagnon et al., 2001; Cazelles et al., 2005). However, these reported associations are not entirely consistent, possibly reflecting the complexity of climatic effects on transmission, and/or the presence of competing factors (Cummings, 2004). While high rainfall or high temperature can lead to an increase in transmission, studies have shown that drought can also be a cause if household water storage increases the number of suitable mosquito breeding sites (Pontes et al., 2000; Depradine and Lovell, 2004; Guang et al., 2005).

Climate-based (temperature, rainfall, cloud cover) density maps of the main dengue vector Stegomyia (previously called Aedes) aegypti are a good match with the observed disease distribution (Hopp and Foley, 2003). The model of vector abundance has good agreement with the distribution of reported cases of dengue in Colombia, Haiti, Honduras, Indonesia, Thailand and Vietnam (Hopp and Foley, 2003). Approximately one-third of the world’s population lives in regions where the climate is suitable for dengue transmission (Hales et al., 2002; Rogers et al., 2006b).