Landscape Fragmentation Shapes Zoonotic Malaria Spillover Risk During Deforestation

Area of Science:

• Ecology
• Epidemiology
• Mathematical Modeling

Background:

• Zoonotic malaria caused by Plasmodium knowlesi is a growing concern in Southeast Asia.
• Deforestation and habitat fragmentation alter human-wildlife-vector interactions, increasing spillover risk.
• The combined impact of host community changes and landscape structure on spillover risk is not well understood.

Purpose of the Study:

• To model how landscape fragmentation influences Plasmodium knowlesi spillover risk.
• To investigate the role of host community composition and density in zoonotic malaria transmission.
• To identify key drivers of spillover risk in deforested landscapes.

Main Methods:

• A process-based simulation model was developed, representing deforestation using the edge ratio.
• The model integrated mosquito abundance, host densities, biting preferences, and reservoir competence.
• Global sensitivity analysis was performed to quantify parameter influence.

Main Results:

• Spillover risk may peak at intermediate edge ratios due to elevated mosquito density and host overlap.
• Changes in host composition can shift the magnitude and location of peak risk.
• Macaque competence emerged as a dominant factor influencing spillover risk.

Conclusions:

• Monitoring macaque infections and mosquito activity in fragmented forest-agriculture edges can help identify high-risk areas for zoonotic malaria.
• Understanding host availability dynamics is crucial for predicting spillover events.
• Further empirical validation is needed to confirm these findings in real-world settings.