The Parsha of Tazria deals with several Negaim, afflictions, of a person’s skin, clothing, or even his house. Ramban states that these afflictions can only apply to Jews. This demonstrates that these Negaim, specifically Tzaraat, are not conventional physical ailments, but spiritual punishments for sins such as arrogance, Lashon Hara, or greed. This is why when someone develops Tzaraat, the Kohen, a spiritual leader, is called, rather than a doctor.
The Sifrei Mussar (ethical works) teach that the word for skin is עור with an ‘ע’, while a homonym (according to Ashkenazic pronunciation) of this word is אור with an ‘א’, meaning light. Similarly, the word for an affliction is a נגע. The letters of this word can be transformed to say ענג, which is delight and enjoyment. Also, the most common affliction in the Torah is צרעת whose letters can be switched to say עצרת, which is a word used for a holiday.
One can learn from this that if someone were to sin, he would contaminate his skin,עור, causing a נגע which would lead to him developing צרעת. All of this can be changed; the נגע is meant to be a wake-up call, telling the person that he is doing bad things. If he adheres to this call, then he will have the opportunity to purify himself. He will be able to change the עור, to אור, the נגע to ענג, and the צרעת to an עצרת.
The Sfat Emet explains the meaning of these changes. He writes that when people were first created, the אור, light, of Hashem came into their bodies. Then Adam sinned and his עור, skin, covered up the light of Hashem. Human skin has pores, which allow the light to penetrate through and guide us, but when we sin, the נגע צרעת covers the pores and does not allow the light to come through. When this is healed, and the afflicted person is allowed back with his family, the נגע is transformed into an ענג because of the happiness, and the צרעת is transformed into anעצרת , a mini holiday for the person who is healed, and returns to his family.