This New York Times article summarizes the complexity of the human-wildlife disease interface. Mink farms in the US, as in the Netherlands and Denmark, have become reservoirs for Covid. And in these infected mink populations, the SARS-CoV-2 virus has mutated then spilled back to humans. What's not clear to epidemiologists is how some humans contracted the mink strain and what other animal species (besides mink and white-tailed deer) now harbor SARS-CoV-2.