Patterns of Urban Housing Shape Dengue Distribution in Singapore at Neighborhood and Country Scales

Dengue is the most important human arboviral disease in Singapore. We classified residential areas into low-rise and high-rise housing and investigated the influence of urban drainage on the distribution of dengue incidence and outdoor breeding at neighborhood and country scales. In Geylang area (August 2014 to August 2015), dengue incidence was higher in a subarea of low-rise housing compared to high-rise one, averaging 26.7 (standard error, SE=4.83) versus 2.43 (SE=0.67) per 1,000 people. Outdoor breeding drains of Aedes aegypti have clustered in the low-rise housing subarea. The pupal density per population was higher in the low-rise blocks versus high-rise ones, 246 (SE=69.08) and 35.4 (SE=25.49) per 1,000 people, respectively. The density of urban drainage network in the low-rise blocks is double that in the high-rise ones, averaging 0.05 (SE=0.0032) versus 0.025 (SE=0.00245) per meter. Further, a holistic analysis at a country-scale has confirmed the role of urban hydrology in shaping dengue distribution in Singapore. Dengue incidence (2013-2015) is proportional to the fractions of the area (or population) of low-rise housing. The drainage density in low-rise housing is 4 times that corresponding estimate in high-rise areas, 2.59 and 0.68 per meter, respectively. Public housing in agglomerations of high-rise buildings could have a positive impact on dengue if this urban planning comes at the expense of low-rise housing. City planners in endemic regions should consider the density of drainage networks for both the prevention of flooding and the breeding of mosquitoes. Plain Language Summary Dengue is among the increasing public health problems to many countries, especially in large urbanized areas. Various climatic and nonclimatic factors interact and shape the disease distribution in endemic cities. In Singapore, types of urban housing influence indoor breeding and dengue cases. The strategic plan of Urban Redevelopment Authority of Singapore focuses on affording public housing in high-rise buildings as a solution for the growing population. In this study, we revisit this observation at a neighborhood and country levels categorizing urban housing of Singapore into low-rise and high-rise housing. A low-rise housing subarea at the neighborhood shows more outdoor breeding in drains and denser drainage network compared to high-rise subarea. At the country scale, risk of dengue is related to the fractions of area or population living in low-rise housing. The distribution map of dengue incidence shows a similar profile to the distribution maps of low-rise housing. This finding suggests that the government strategic plan to afford public apartments in urban agglomerations of high-rise buildings does not increase the risk of dengue transmission. On the other hand, the higher risk in low-rise housing is likely related to more conducive factors for indoor-outdoor breeding habitats.