I am definitely pro vaccination, and the question is a bit morbid because people would die, but assuming that we didn't treat or vaccinate people for fatal diseases such as Ebola or the black death, would the surviving people pass along a trait that eventually would lead to near immunity for that disease?
Are there any examples of diseases that humans "contract" but they are immune to? Or any examples of immunity through human evolution?
What about in animals? Are there diseases that have been naturally eradicated?