Disease exist either in Body or in the mind.
Body and mind are are inter related. If there is imbalance in body, mind suffers and vice versa.
Epilepsy, irritation of the skin, pimples, acne, zits, pain in any body part, digestion ailments, problems of the heart, eyes, nose, throat and mouth. These ailments reside in the body.
Sex, anger, depression etc exist in the mind.
Body's dosha - Vata dosha (air), Pitta Dosha (fire) and Kapha Dosha (land)
Mind's Dosha- Raja and Tama
[Dosha means an imbalance.]
When there is a balance the person is healthy. When there is an imbalance (Dosha) person suffers from ailment.
There should be a balance in Vata, Pitta and Kapha for good health. If any of these get aggrevated or weak, ailment occurs. It is because of this imbalance ailment occurs.
That's why they are called Doshas imbalance.