if you control all 5, there are no ways to prevent them from rezzing if the corpses are split in different LOS. The healer can go around the pole all day. and you wouldn't be able to kill him. Unless you split your shamans to camp different locations, but this way you can't win either.

What Ellay has suggested is the only way I find effective against this. Kill one. then camp him. drink if you have to. Don't go chase their healer if he is so determined to hug the pole to avoid you. Sooner or later, they will attempt a stealth rez from different angles. Try to make your kill then. Or simply kill the dps who will try to distract you when their healer attempt to rez.

For the 2 or 3 healers team, I find it to be better to kill the healer after your initial EM nuke. Use your EM nuke on a dps. Then kill another healer rather than target another dps. This has worked better for me.