Urbanization Drives Dengue in Cambodia

In a rapidly changing world, mosquito-borne diseases pose major global public health concerns. The threat of mosquito-borne disease burden is further compounded in low-income and rapidly urbanizing regions where current healthcare infrastructure is inadequate in treating and preventing outbreaks. Dengue virus (DENV), a flavivirus transmitted by the urban-dwelling mosquito, Aedes aegypti, is the most rapidly spreading mosquito-borne disease worldwide, with 50-100 million infections occurring annually. There is currently no widely available vaccine or specific therapeutic to prevent or cure dengue. Half of all DENV infections occur in Southeast Asia, wherein Cambodia experiences one of the highest rates of infection, with an average of 103 cases per 10,000 people, yet there are very few studies of dengue dynamics in Cambodia to date. Because the country is currently experiencing the greatest rate of urbanization in Southeast Asia, it is an urgent region of study on the interplay between climate, urbanization, and dengue. In this analysis, we use public health surveillance and remote sensing data to evaluate the relationship between dengue risk and urbanization at two spatial resolutions: provincial (24 provinces) and commune level (96 communes, Phnom Penh province). After accounting for climate, we found that Human Footprint Index, the urbanization metric used in the provincial model, had no significant effect on dengue incidence. However, we found that within the highly urbanized province of Phnom Penh, dengue incidence increased with urban infrastructure, with the largest effect occurring in areas with low Relative Wealth. We found that dengue may occur across urban to rural interfaces in Cambodia, however, the degree of urbanization and the interplay between socio-economic factors influence the magnitude of within-city dynamics.