“In 2014, I spent 10 days hiking through the Mapacho River Basin, one of the most biodiverse places on Earth in Peru’s western Amazon region. I walked along trails shaded by a dense canopy, waded through rivers and slept in shelters designed to dry coca leaves. I was there leading a research team collecting data on the livelihoods of Indigenous farmers. Shortly after I left, though, something arrived that would devastate the communities. I returned in 2020 to deserted homes, increased poverty and stories of a disease that caused it all.”