The town of Borbón in northern Ecuador houses various government and religious offices, along with a regional hospital. Despite these urban-like features, Ecuador categorizes Borbón as rural. This classification suggests that Borbón's residents should be relatively protected from dengue, a disease transmitted by the Aedes aegypti mosquito, which thrives in urban environments and breeds primarily in artificial containers, according to the World Health Organization. However, dengue is increasingly prevalent in Borbón, where the density of Aedes aegypti mosquitoes can rival that of urban areas, as reported by researchers in the October issue of Social Science and Medicine.
Epidemiologist Joseph Eisenberg of the University of Michigan in Ann Arbor argues that terms like 'urban' and 'rural' are more political than health-related. 'Viruses don't adhere to these politically defined categories,' he notes. Misclassifications of urban and rural areas have significant public health implications. For instance, labeling dengue as an urban disease and malaria as rural influences where governments focus their efforts in tracking and preventing these diseases, often neglecting areas that don't fit neatly into these categories.
In Ecuador, officials often use population density to label a parish as 'urban' or 'rural,' similar to towns or cities in the United States. However, Eisenberg's team found that nearly 100 residents across Esmeraldas province, including Borbón, defined these terms based on access to government services and amenities like trash collection, clean water, and paved roads. Urban areas were perceived as having these amenities, while rural areas did not. This divergence means official health guidelines often fail to align with local realities.
Public health officials in Ecuador advise residents in designated urban areas to eliminate or cover open water sources where A. aegypti mosquitoes lay eggs. However, many neighborhoods classified as rural have urban-like infrastructure and population density, such as Borbón. Conversely, some neighborhoods classified as urban lack essential municipal services. Residents in these areas believe it is the government's responsibility to improve infrastructure to curb disease spread.
Health officials occasionally distribute bed nets, though this approach is debatable since dengue-carrying mosquitoes bite during the day. Residents in Esmeraldas note that these measures miss the mark; mosquitoes breed in puddles in areas without paved roads and storm drains. Without addressing these issues, dengue will continue to spread.
Sadie Jane Ryan, a medical geographer at the University of Florida in Gainesville, highlights that structural services and amenities play a more significant role in dengue infections than mosquito abundance. Her research in southern Ecuador shows that widespread air conditioning can reduce dengue even in mosquito-dense areas, while inadequate plumbing and trash collection increase the risk. Ryan's 2021 study also underscores the risks in areas that fall between the urban-rural dichotomy, where water storage practices can facilitate mosquito breeding.
Eisenberg and colleagues advocate for a more nuanced approach to mapping disease risk, integrating urban-rural classifications with other risk factors that consider the perspectives of local populations and the ecology of mosquitoes. This approach, using theories like assemblage and political ecology, could better identify areas conducive to disease transmission and the structural factors facilitating it.
As climate change makes more regions hospitable for mosquitoes, understanding how these diseases spread is crucial. 'Where do epidemiologists get the idea that 'urban' and 'rural' are meaningful disease descriptors?' asks James Trostle, a medical anthropologist at Trinity College in Hartford, Conn., and coauthor of the new study. 'The mosquito is concerned with where it can survive.'
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