Study supported by a CIGH Global Health Seed Grant finds that malaria cases resurged rapidly in rural areas of the Brazilian Amazon after a successful local prevention program ended, and identifies proximity to forest edge habitat among the main predictors of transmission. Sustained public health investment is key to lasting elimination, researchers say.

A new study from Stanford University, SAMA Health In Harmony Brazil, and collaborators reveals the importance of continuous malaria control efforts in susceptible areas of the Amazon, particularly where land use changes like deforestation and damming affect mosquito habitat and breeding patterns. The research was supported by a Global Health Seed Grant from the Stanford Center for Innovation in Global Health.

The new research, published in GeoHealth, focuses on the large municipality of Altamira in the Brazilian Amazon, where a dam was constructed on a river running through the community beginning in 2011. While the dam was being built, local health authorities increased malaria control efforts, and cases dropped sharply.  But when these control programs ended, cases again rose sharply in some parts of the region.

To understand what caused these changes, researchers examined malaria case data from 150 health centers from 2006 to 2020, comparing it with information about the environment and local population. 

Their key findings shed new light on malaria disease transmission and control efforts in the Amazon:

“These results show that both the environment and human populations influence malaria risk over time. The findings also reveal that stopping control programs can lead to a quick return of malaria, highlighting the need for continuous efforts, especially in rural and environmentally changing areas,” the authors write.

The publication also emphasizes the value of modeling simulations to quantify how policy shifts can influence malaria transmission in the Amazon. 

Lead author Eloise Skinner, PhD, a postdoctoral research fellow at the Frazer Institute at The University of Queensland who conducted this research during her time in Stanford’s Mordecai Lab, said the project taught her a great deal about what meaningful impact looks like in global and planetary health research. 

“We tend to measure research impact through large-scale analyses and citation counts, but what this project reinforced is that real-world impact can be deeply fine-scale, village-level even,” she said.

The research team worked closely with SAMA Health in Harmony, a local nonprofit with a proven record of successful planetary health interventions in the region, to design the study to answer the questions most important to the nonprofit and local community.

“This work was entirely born from the (CIGH) seed funding opportunity, and it pushed me to really think about how research can support a not-for-profit’s objectives, navigating the logistical realities of collaborating with people on the other side of the world with different priorities, timelines, and budgets,” she said. “Research that directly works with a not-for-profit’s approach and engages with their core questions carries real weight for those organisations by making the case for their work, and I think that will matter more than citation counts in this context.”

Daniela de Angeli Dutra, PhD, a Stanford affiliate at the time of the research, was joint lead author with Skinner and is now at the School of Environmental and Natural Sciences, Bangor University in Bangor, UK. Erin Mordecai, PhD, associate professor of biology at Stanford and a CIGH Faculty Fellow, was senior author. Additional authors include Érika Pellegrino, MD, Founding Member & Health Advocacy Consultant at Health in Harmony, Osvaldo Correia Damasceno, a professor at the Federal University of Pará medical school in Altamira, Brazil, and, Sakib Burza, chief of health and innovation at Health in Harmony and an honorary professor at the London School of Hygiene and Tropical Medicine.