It is possible to catch leprosy from an armadillo if you are a human or an armadillo. Were you to handle an infected armadillo and contract the disease unwittingly you might never notice, around 95% of humans are immune to leprosy. Even if you did contract leprosy it could easily be stopped early on. That is for real leprosy, what about imaginary leprosy? What happens if I told you that you had leprosy – and you believed me?
If you believed that you had leprosy from your excessive armadillo handling sessions, something curious would happen. You would look up the symptoms, then they would manifest. Your skin might become rough, your muscles would feel much weaker and you might notice that the nerves in your hands and skin aren’t working, it is harder to feel things. The problem is this; nothing at all is hurting you, you should be healthy. Then medicine enters.
Medicine would have little physical effect on you, after all there is nothing to fight. You would suffer the side effects, but if you believed the medicine would work, your symptoms would disappear.
In The Mind
It all felt real, in fact those effects were real, though there was only one external factor. The idea of leprosy. A person believing they had a disease, as long as they know the symptoms, will develop the symptoms. This is the extreme case of mind over matter and it is most definitely a real problem. This is the nocebo effect. Nocebo comes from the Latin for I will harm. It is the evil twin of the more famous Placebo effect.