(Chicago) Neighbor will not clean infested unit in condominium

[Patrick Sturgulewski]

Hello, I currently own one unit in a self-managed condo. The condo is managed by an association, and I have the opportunity to take the function of a president. The issue lies with the previous president (who I shall call A), who also lives in a unit in the condo that is infested with bedbugs. The bedbugs are spreading from A’s unit, and their presence is preventing me from finding an agent that will list my unit for sale. I have attempted and failed to reason with A; despite an exterminator documenting that there was a heavy bedbug infestation in A’s unit and insinuating that they originated from it, A denies the issue each time it’s brought up and refuses to have his unit cleaned. How can I legally force A to have an exterminator treat his unit? Is there any legal action I can take to get some leverage in this situation?