Or HaChaim on Leviticus 13:46/אור החיים על ויקרא י״ג:מ״ו

1 כל ימי אשר הנגע בו, all the days that the plague is within him, etc. This means that as long as his sin is still part of him he remains in the state of ritual impurity. The emphasis expressed by the words טמא הוא after the word יטמא is a reminder of Jeremiah 2,19 where the prophet exclaims: תיסרך רעתך, "your discipline has been the result of your wickedness." In other words it was not G'd who inflicted these misfortunes on the sinner but the sins he committed. Jeremiah expresses a similar thought in Lamentations 3,39: "Of what shall a living man complain?! Each one of his own sins." Yalkut Shimoni item 1040 on this verse is worth studying. You may want to read what I have written on Genesis 4,4 אם תיטיב שאת.