13:1 The Lord spoke to Moses and Aaron, saying, 2 “When a person has on the skin of his body a swelling or an eruption or a spot, and it turns into a case of leprous  disease on the skin of his body, then he shall be brought to Aaron the priest or to one of his sons the priests, 3 and the priest shall examine the diseased area on the skin of his body. And if the hair in the diseased area has turned white and the disease appears to be deeper than the skin of his body, it is a case of leprous disease. When the priest has examined him, he shall pronounce him unclean. 4 But if the spot is white in the skin of his body and appears no deeper than the skin, and the hair in it has not turned white, the priest shall shut up the diseased person for seven days. 5 And the priest shall examine him on the seventh day, and if in his eyes the disease is checked and the disease has not spread in the skin, then the priest shall shut him up for another seven days. 6 And the priest shall examine him again on the seventh day, and if the diseased area has faded and the disease has not spread in the skin, then the priest shall pronounce him clean; it is only an eruption. And he shall wash his clothes and be clean. 7 But if the eruption spreads in the skin, after he has shown himself to the priest for his cleansing, he shall appear again before the priest. 8 And the priest shall look, and if the eruption has spread in the skin, then the priest shall pronounce him unclean; it is a leprous disease.
9 “When a man is afflicted with a leprous disease, he shall be brought to the priest, 10 and the priest shall look. And if there is a white swelling in the skin that has turned the hair white, and there is raw flesh in the swelling, 11 it is a chronic leprous disease in the skin of his body, and the priest shall pronounce him unclean. He shall not shut him up, for he is unclean. 12 And if the leprous disease breaks out in the skin, so that the leprous disease covers all the skin of the diseased person from head to foot, so far as the priest can see, 13 then the priest shall look, and if the leprous disease has covered all his body, he shall pronounce him clean of the disease; it has all turned white, and he is clean. 14 But when raw flesh appears on him, he shall be unclean. 15 And the priest shall examine the raw flesh and pronounce him unclean. Raw flesh is unclean, for it is a leprous disease. 16 But if the raw flesh recovers and turns white again, then he shall come to the priest, 17 and the priest shall examine him, and if the disease has turned white, then the priest shall pronounce the diseased person clean; he is clean. (ESV)
 13:2 Leprosy was a term for several skin diseases