Dengue is classified as an urban disease. Mosquitoes don’t care

The city of Borbón in northern Ecuador is home to several government and religious offices and a regional hospital. However, Ecuador classifies Borbón as rural. That designation means Bourbon residents should be relatively safe from dengue, a disease carried by a species of mosquito that, according to the World Health Organization, “lives in urban habitats and breeds primarily in man-made containers.”

But dengue is spreading throughout Bourbon, where their density Aedes aegypti Mosquitoes may mirror that of urban areas, researchers report in October Social Science and Medicine. Terms like UrbaN AND rural have more to do with politics than public health, says epidemiologist Joseph Eisenberg of the University of Michigan in Ann Arbor. “Viruses do not follow these politically defined entities.”

Misconceptions about what constitutes an urban or rural area have far-reaching public health implications. Classifying dengue as urban or malaria as rural affects where governments seek, track and work to prevent these diseases, leaving less defined regions behind. These misconceptions also shape how people react to such efforts.

In Ecuador, government officials tend to use population density as shorthand for applying the label “urban” or “rural” to a parish, similar to a city or town in the United States. But the nearly 100 people Eisenberg’s team interviewed across Esmeraldas province, which includes Borbón, often used a different shorthand — access to government services and amenities, such as garbage collection, a clean water supply and roads. paved. Urban areas had such amenities, people said, while rural areas did not.

These different definitions mean that official guidelines often do not match local realities. Public health officials in Ecuador are asking people living in certain urban areas to empty or cover any open water sources — prime places for A. funnel mosquitoes to lay eggs. Such open sources may include water stored in outdoor pots or items such as trash can lids and flower pots that collect rainwater. But many people live in neighborhoods classified as rural that have the infrastructure and population density that reflects a city—think Borbón.

Others, meanwhile, live in neighborhoods classified as urban, but do not have adequate municipal services and amenities. Residents of these areas say the onus is on the government to build the infrastructure needed to stem the spread.

The country’s health officials occasionally distribute bed nets to residents (itself a controversial approach, since the mosquitoes that carry dengue are daytime biters). But residents in Esmeraldas say the purported purposes of the bed nets still miss the point. Mosquitoes collect puddles in areas without paved roads and storm drains, one resident said. If the government does not fix those roads, people will continue to get dengue.

Access to more structural services and other facilities, in fact, appear to be bigger drivers of dengue infections than the abundance of mosquitoes, says Sadie Jane Ryan, a medical geographer at the University of Florida in Gainesville. Her work in southern Ecuador has shown, for example, that the widespread availability of air conditioning can reduce dengue, even in areas with many disease-carrying mosquitoes. Meanwhile, inadequate plumbing and garbage collection increase the risk of dengue disease.

Ryan’s research, reported in 2021, it also demonstrated the unique risks associated with often neglected areas that fall somewhere between the urban-rural dichotomy. People in households with reliable water rarely store water outside, while people in households without plumbing store water outside but go through it quickly, Ryan says. “In that really interesting middle ground where… [people] do not have reliable access to water, [they] tend to store water long enough for mosquitoes to breed.”

Eisenberg and colleagues argue that curbing the transmission of mosquito-borne diseases worldwide requires overlaying urban-rural maps with other measures of disease risk that decentralize the perspectives of distant bureaucrats and the mosquitoes at the center and the people exposed to them. Assemblage theory, for example, would identify ecological pockets friendly to them A. Egypt. Political ecology theories, meanwhile, would factor in structural forces that facilitate disease transmission, such as unreliable utilities.

Understanding how mosquito-borne diseases are spread is a pressing public health concern as the climate warms and mosquitoes find more hospitable climates in which to thrive (SN: 26.8.24). So getting that right matters, say Eisenberg and others.

“Where do epidemiologists… get the notion that ‘urban’ and ‘rural’ make sense as descriptors of disease?” asks James Trostle, a medical anthropologist at Trinity College in Hartford, Conn., and a co-author of the new study. “The mosquito cares where it can live.”