There isn't, unfortunately. There
is a "wipe out all Red Darwinians" objective, but no "Wipe out infection" objective.
I suppose you could have the Triffids launch eggs really rapidly, and not very far, but only hatch into Spirits, then have enemy engineers pick them up and take them to Incubators. Then you have a spawn system that works kinda like Biosphere's(as in, you're gonna get more Darwinians) but you can destroy it(take over the incubators, destroy the Triffid or Engineers), it's also of less value to you once you're done than the Virus.
Now, let's see here, where was I?

Oh yeah, there's no Wipe out Infection" objective.
