(Bamidbar 5:2) "that they send out of the camp": I understand this to mean from the Levite camp alone. Whence do I derive that the Israelite camp is also meant? From (Bamidbar 5:3) "Outside the camp shall you send them." (Bamidbar 5:3) "and they shall not make unclean their camps in whose midst I dwell": This is the camp of the Shechinah. — But even if this were not mentioned, I could derive it a fortiori, viz. If those with dead-body tumah are ejected from the less stringent camp, that of the Israelites, how much more so are they ejected from the more stringent camp, that of the Shechinah.
If so, why is "and they shall not make unclean their camps" needed? To teach that we do not punish by an a fortiori argument. R. Yehudah says: There is no need (for the verse to teach that they are sent out of the camp of the Shechinah), for it follows a fortiori, viz.: If those with (dead-body) tumah are ejected from the less stringent camp, (that of) the ark (i.e., the camp of the Levites), how much more so are they ejected from the more stringent camp, (that of) the Shechinah, (R. Yehudah obviously holding that we do punish by an a fortiori argument).
If so, why is it written "and they shall not make unclean their camps?" Because from "they shall send out from the camp every leper and every zav and every tamei meth," I would understand that they are all sent to one place; it is, therefore, written in respect to a leper (Vayikra 13:46) "Solitary shall he sit" — that no other unclean ones sit with him. I might then think that zavim and the tamei meth are sent to one camp; it is, therefore, written "and they shall not make unclean their camps" — to assign a separate camp for each.
These are the words of R. Yehudah. Rebbi says: There is no need (for the above). A leper was included in the general category (of the unclean), and left the category (for special mention) to teach concerning the category, viz.: Just as a leper, whose tumah is most stringent — his sending is more stringent than that of his neighbor, so, each one whose tumah is more stringent, his sending is more stringent than that of his neighbor.