Mange
I thought of sarna, although not an English word, but Portuguese/Spanish for scabies.
leather
Pelt
pelt
hide pelt
ringworm a fungal disease:)x
hide as in animal hide
The etymology of disease is from the world 'ease' dis + ease
The anagram for the word disease is seaside.This is the only other seven letter word from the letters 'disease'.
skin, pelt
Morbid. The Latin word for disease is morbus.
Skin
Shed