The list of challenges in the field is long and diverse. Keeping yourself and the folks helping you alive and healthy tops the list. People always ask me about attacks from animals I've photographed -- like tigers, rhinos, elephants, jaguars, bears -- but I always say that the most dangerous creatures are the microscopic variety. Although I've been charged by animals, so scared I could barely breathe with my heart pounding so hard I thought it would explode, I've never been hurt. But I have had malaria, Dengue fever, parasites, worms, amoebic dysentery, and various unexplained illnesses.