São Paulo urban heat islands have a higher incidence of dengue than other urban areas

Abstract

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 temperature, 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.

The impact of temperature on mortality in a subtropical city: effects of cold, heat, and heat waves in São Paulo, Brazil

“…Most cities including São Paulo show a greater heat island effect such as increased rate of infectious disease and much higher mortality during heat waves enhanced by the urban heat island (Araujo et al, 2015; Tan et al, 2010). Urbanization is increasing rapidly worldwide (Allender et al, 2011), which could exacerbate the effect of heat in the future.…”

Joint effects of climate variability and socioecological factors on dengue transmission: epidemiological evidence

“…The influence of urbanisation on dengue transmission was investigated in Pakistan , Taiwan , Mexico , Costa Rica and Brazil . In these studies, urbanisation was defined by the proportion of people living in urban areas , urban heat island or by some socioecological factors .…”

“…Most of these studies found a significant association between dengue and high population density. However, a single study in Argentina reported that rural areas with a low population density may experience severe epidemics in the absence of a tap water supply .…”

Mudanças climáticas e saúde urbana

“…A viabilidade do vetor na cidade de São Paulo e o risco de ocorrência de grandes epidemias decorrentes da adaptação do mosquito às condições adversas a ele presentes na cidade foram hipotetizadas por Louise, Vidal e Suesdek (2015), assim como a existência de associação entre o maior risco de ocorrência de dengue e as ilhas urbanas de calor da cidade, as quais apresentariam condições mais adequadas para a proliferação de Aedes aegypti e a transmissão do vírus dengue (Araujo et al, 2015).…”