Urban
heat islands are characterized by high land surface
temperature, low
humidity, and poor vegetation, and considered to favor the
transmission of the
mosquito-borne
dengue fever that is transmitted by the
Aedes aegypti mosquito. We analyzed the recorded
dengue incidence in Sao Paulo city,
Brazil, in 2010-2011, in terms of multiple environmental and socioeconomic variables.
Geographical information systems, thermal remote sensing images, and
census data were used to classify city areas according to land surface temper- ature, vegetation cover,
population density,
socioeconomic status, and
housing standards. Of the 7415
dengue cases, a majority (93.1%) mapped to areas with land surface
temperature >28 ◦ C. The
dengue incidence rate (cases per 100,000 inhabitants) was low (3.2 cases) in high vegetation cover areas, but high (72.3 cases) in low vegetation cover areas where the land surface
temperature was 29 ± 2 ◦ C. Interestingly, a multiple
cluster analysis phenogram showed more
dengue cases clustered in areas of land surface
temperature >32 ◦ C, than in areas characterized as low socioeconomic zones, high
population density areas, or
slum-like areas. In
laboratory experiments, A. aegypti
mosquito larval development,
blood feeding, and
oviposition associated positively with
temperatures of 28-32 ◦ C, indicating these
temperatures to be favorable for
dengue transmission. Thus, among all the variables studied,
dengue incidence was most affected by the
temperature.