Why is Rebie Most deadly disease in the world? Science could not find the treatment

Rebies, the disease that is with the cutting of the dog, cat or monkey. Let you know that it is considered the deadly disease in the world. Once it is a disease, it is not possible. So far, only 6 people in the world have seen the rebies and they survived. Otherwise, the death of the relaxes is definite 100%. The biggest thing is that this disease can be stopped but once shown its symptoms, it cannot be treated.