Infectious etiology is not the same as being contagious. We know HPV causes increased cancer risk, but we don't treat folks with those cancers as contagious. They're not. But their malignancies do have an infectious cause - infection earlier in life. That's the relationship being proposed here with Alzheimer's. Understanding the nature of a disease is a prerequisite for developing better treatments. We should not the imaginary social fears of the uninformed get in the way of that exploration.