Your question is a lot like asking "does health exist?"
Health is the opposite of disease. Some diseases are heart disease, kidney, infectious, autoimmune, poor eye vision, genetic disorders, chronic pain, broken limb, depression, etc.
So, the state of unhealth exists and health is the opposite of this. Does every human suffer from some health problem even in the tiny least? Yes. Some are in excellent health, some in good health, and some in poor health but no one is in 100 percent perfect health. But it can be shown what health is not. When does a person have a healthy kidney? When it functions within acceptable parameters. When is a person healthy? When he functions within acceptable parameters.