It's entirely possible to balance infectors without necessarily nerfing them. Consider changes or additions that would reduce their effectiveness in PvP without altering their functionality in PvE:
- Make the growths turn invisible when going into aim mode.
- Ability to remove infector growths by rolling (come on—this one should have always been in).
- A shield with resistance to the poison damage from infector growths.
- A perk that makes it so bugs don't hatch from growths on you.
- Death by bugs doesn't count as a "kill", but just a death (like if you fall into a pit).
- Healing someone with a BMG instantly removes any growths on them.
- Homing bullets can't hit players who are moving with Blur.
- Etc.
I don't want to see Infectors nerfed—I don't really want to see anything nerfed. I think that a healthier balance can be achieved by tweaking other elements of the game. Not only does it add more strategy to PvP, but it can promote a more flexible metagame.