Is a leper, or hath a running issue - See the case of the leper treated at large in the notes on Leviticus 13 (note) and Leviticus 14 (note); and for other uncleannesses, see the notes on Leviticus 15 (note).
4. A leper. Most of the defilements that might come to a priest would be only temporary in nature, and exclusion from the sanctuary would last only till evening. Those, however, who contracted leprosy or had a running sore were excluded until declared clean again, however long the time might be. During the time of their separation they were supported as were the other priests, but might not eat of things offered, since that would involve the bearing of sin.