Mosquitoes are often called the deadliest animals on Earth—and for good reason. Each year, they are responsible for an estimated 700,000 to 1 million deaths worldwide through the transmission of diseases such as malaria, dengue, and yellow fever. In Costa Rica, Dengue is the most common mosquito-borne illness, transmitted primarily by Aedes mosquitoes. Unlike many other infectious diseases, vector-borne pathogens are tightly linked to environmental conditions. Because mosquitoes are ectothermic, variables like temperature, humidity, and rainfall directly influence their survival, reproduction, and ability to transmit viruses. In a tropical country like Costa Rica—where warm temperatures and heavy rains are common—conditions are often ideal for dengue transmission.
This past year, I had the opportunity to contribute to the Disease Ecology in a Changing World project at Stanford University, working alongside collaborators at the University of Costa Rica. Our shared goal was to better understand how land use shapes rural dengue risk. While dengue is often associated with dense urban areas, rural landscapes—especially those undergoing agricultural expansion—may also create conditions that support mosquito breeding and virus transmission.
Reports from the field
We spent two weeks conducting fieldwork across a range of rural communities. Each day began with household surveys, where we carefully searched yards and surrounding areas for mosquito breeding habitats. Aedes mosquitoes thrive in small collections of standing water: discarded tires, plant pots, tarps, buckets, and water storage containers. In many parts of Costa Rica, families collect rainwater for household use. While practical and resourceful, these storage practices can unintentionally provide ideal sites for mosquitoes to lay eggs.
Community engagement quickly became one of the most meaningful aspects of the project. Residents were eager to talk about the mosquitoes in their yards and the challenges they face. We shared practical strategies to reduce breeding habitat—emptying standing water, covering containers, and maintaining yards—and made sure to remove water from any containers we encountered during our surveys. Conversations often turned to prevention methods such as bed nets and window screens, especially during peak biting times.
While some team members focused on larval surveys, others searched for adult mosquitoes resting in cool, shaded areas around homes. Collecting adult mosquitoes allows us to identify species and test whether blood-fed individuals are carrying dengue virus. At the same time, our collaborators launched drones over study sites to capture high-resolution imagery. The long-term goal is to develop tools that can identify potential breeding habitats from above, linking field observations with landscape-scale data.
Our study sites spanned diverse land-use types, including pineapple farms and palm plantations. Worker housing is often situated along the edges of these agricultural fields, creating interfaces where human activity, environmental change, and mosquito habitat overlap. These transition zones may play an underappreciated role in shaping dengue risk.
Building bridges
This collaboration highlights how disease ecology connects field research, community engagement, and remote sensing. By understanding how land-use patterns influence dengue transmission, we can better identify areas at risk and inform targeted, locally grounded public health strategies. In a changing climate and rapidly transforming landscapes, building these bridges between environmental and human health has never been more important.
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