An integrative approach to determining spatial distribution of mosquito-borne illness risk 

Mosquitoes pose a significant threat to human health as vectors for diseases such as malaria, dengue and many other life-threatening illnesses. Because of their potential to cause significant health issues, researchers are continuously studying how mosquitoes disseminate disease and what factors could put someone more at risk of coming into contact with an infected mosquito.

Given that the majority of the human population can be found living in urban settings, one research question of interest focuses on how the risk of an urban dweller coming in contact with an infected mosquito differs across locations in a city. However, this can be difficult to determine due to the complex and ever-changing environmental and socio-political factors in each city and the lack of interdisciplinary research on mosquito-borne diseases.

In response to this question, CEID’s Michelle Evans led a project with John Drake and Courtney Murdock to utilize an integrative approach to study the spatial patterns of mosquito burden. This approach accounted for both ecological and social factors in its analysis.

To demonstrate their approach in Bengaluru, India, the research team classified land into four categories–rural, village, town and colony–based on the amount of impervious surface and housing types on each patch. Rural areas were those with low levels of impervious surfaces and no housing, villages were those with moderate levels of impervious surfaces and traditional housing, towns were those with high levels of impervious surfaces and traditional housing and colonies were classified as having a moderate level of impervious surfaces and western-style housing. 

For each of the four categories of land types, four study sites were randomly selected. At each study site across the four categories, the research team recorded mosquito abundance as well as local perceptions and experiences with mosquitoes through interviews with local residents.

The researchers found no evidence for a significant difference in mosquito abundance across the urban gradient, but individual experience with mosquitoes ranged significantly across the gradient, likely due to differences in how they used outdoor space and their ability to avoid dangerous areas. For example, those in the urban colony areas often reported using outdoor spaces for leisure and recreation, so they could avoid them if necessary.

On the other hand, those in less urban areas may be unable to avoid some outdoor areas that have high densities of mosquitoes. For example, one individual reported that they had to enter areas with high mosquito density to access water to do household chores. Another study participant reported heavy mosquito prevalence near the bus stop where they had to wait for the bus to get around town. In these cases, the individuals felt they lacked the flexibility to avoid the mosquitoes compared to those living in colonial areas. 

The research team believes this integrative approach allowed their research to be significantly more informed, especially as it pertained to the perceived health burden of mosquitoes across the urban gradient even as actual abundance remained constant. Future research on infectious diseases in urban settings could benefit from adopting a similar integrative approach to get a more thorough understanding of how disease burdens differ across spatial and social scales.

To learn more, read the article here.

By Amanda Budd