(Spoiler ahead, especially if you haven't watched DS9 Season 7)

Towards the end of the Dominion War, the founders and the Great Link become infected with a disease, that we later learn was planted by Section 31 through Odo, and infected to the rest via linking. Odo linked with the Female Changeling at the beginning of Season 6, and from that point the wormhole was impassable to the Dominion (due to the mines and then the wormhole prophets), so how did he or she pass the disease to the Great Link?