My tank recently had a small outbreak of columnaris (my fault since I didn't use a QT tank for new fish) The disease surprisingly and thankfully did not spread to any other fish that I know of except for the ones who already had it. I did not separate the sick because I assumed the water had already been infected and I should treat the whole tank for it rather than just the infected since all of the fish might have been exposed.
One of the infected died today and I didn't see it due to the plants and decorations until I noticed my pleco feasting upon one of the sick's body (which I removed prompty). Would this be worse than the normal symptoms of the outbreak, and would I need anything special for this? I've started treatment with Furan-2 already. Would this treatment still work if the fish ate the columnaris? Or would I now need something more ?