Life-threatening fungal infections are on the rise as populations with weakened or suppressed immune systems increase. At the same time, climate change is predicted to increase the dispersal of fungal spores in the environment and to select for fungi adapted to growth at high temperatures, thus increasing the likelihood of human infection. We recently discovered that heat stress increases drug resistance and the overall mutation rate in the major disease-causing fungus Cryptococcus. Specifically, we found that the movement of some mobile genetic elements, called transposons or ‘jumping genes,’ is stimulated by heat stress at human body temperature. These movements result in genetic mutations that can alter gene function and/or expression and lead to adaptation. The goal of our research is to understand how pathogenic fungi adapt in response to stress to survive the environment-to-host transition, develop drug resistance and cause persistent human disease.