医学百科 The Medicine Book (Big Ideas Simply Explained)
Kreutzfeldt-Jakob disease, a fatal brain disorder, and Alzheimer's disease, an irreversible and ultimately fatal neurogenerative disease that accounts for two-thirds of dementia cases.
Swine flu arose as a normal, nonlethal flu in the spring of 1918, but somehow over the following months, no one knows how or where-it mutated into something more severe.