Forest restoration may temporarily increase disease risk before long-term benefits emerge

While deforestation drives the spread of dangerous diseases like malaria and COVID-19 by forcing humans into closer contact with wildlife, new research reveals a surprising twist: restoring damaged forests can also temporarily heighten disease risks before ecosystems stabilize.

The counterintuitive finding comes from the first comprehensive analysis of how habitat restoration affects zoonotic diseases—infections that jump from animals to humans. Lead researcher Adam Fell from the University of Stirling analyzed thousands of scientific studies, ultimately finding only 39 that examined this crucial relationship. “The results were very context-dependent,” Fell explained, highlighting how little scientists understand about restoration’s disease implications despite global efforts to rebuild degraded ecosystems.

The temporary spike in disease risk occurs because rodents—notorious disease carriers—often colonize disturbed landscapes first during restoration. This early wave can bring increases in illnesses like hantavirus before larger predators like bobcats and ungulates return to restore natural balance. In Brazil’s Atlantic Forest, researchers documented how mosquitoes increasingly fed on humans when deforestation eliminated their preferred animal hosts, demonstrating the complex relationship between habitat disruption and disease transmission.

Despite these short-term risks, the research doesn’t diminish the critical importance of forest restoration for combating biodiversity loss and climate change. Instead, it suggests that restoration projects should incorporate disease monitoring and mitigation strategies during vulnerable early phases. As ecosystems mature and find their natural balance, the long-term benefits of restoration far outweigh temporary disease risks, making habitat recovery essential for both planetary and human health.