I just want to answer this question not as a muslim but as a doctor

لماذا امي شفيت من مرض ليس له دواء عندما اتوا فئة من المؤمنين المسيحين بعيسى انه الله و صلوا من اجلها و ابتهلوا الى الله و الميسح عليه السلام؟

If you mean this disease is cancer
Cancer can be treated by operation,chemo therapy &radiotherapy
Early cases can be completely cured
Other cases can be cured but it may return again,Hafez Allah waledatek min haza
If you mean hepatitis,virus C or B,there are many cases which can be completely cured but most cases proceed to liver failure