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One of the great challenges in ecology and evolutionary biology is to explain disease, whether caused by infectious agents such as parasites and pathogens, or by the deterioration or transformation of cellular behavior and function, a prime example of the latter being cancer. Decades of observation and research suggest that successfully treating disease requires insights into how the environment mediates the interactions between disease causing agents (DCAs) and diseased individuals. A major finding is that single factor, targeted therapies are not only likely to fail in controlling or eradicating many DCAs, but are also likely to select for resistance, reducing options for subsequent treatment attempts, and in cases of infectious DCAs, rendering therapeutic agents (e.g., antibiotics) obsolete. I argue that meeting the growing challenge of treating disease in agriculture and animal husbandry, in protected and domesticated species, wildlife, and in the human population will require a fundamental understanding of ecological interactions at sites of infection or disease. I discuss different ways in which components of such disease ecosystems mediate DCA and therapeutic dynamics and resistance evolution, and derive a very simple mathematical criterion for therapeutic success. I then touch on how fundamental insights as revealed by the processes of evolutionary rescue and competitive release can help understand why therapies succeed or fail. Finally, I present six “wedges” that can each contribute alone, or as part of multi-pronged approaches to successfully treating disease.
This paper will be subsequently published as a chapter in an edited book: Hochberg ME. Curing disease. In: Unsolved problems in ecology. Eds: Dobson, A.P., Tilman G.D. & Holt R.D. Princeton University Press.