If they are ill, or they are caring for patients, quarantine means scarcity. The clotting drugs they need to keep the failing splenectomy in Trauma-A alive are not available and he's crashing. The last cylinder of O2 is about to run out for the old lady with ARDS.
Scarcity can also come in the form of information - nobody on the outside is telling them what's going on, they don't have the data they need, etc. This also breeds uncertainty and finally desperation.
If they are infected, that's a whole countdown timer itself. Patients start to manifest symptoms - are they the disease or unrelated? Tell them they are sweating and clammy - is it just nerves, or the air handler, or is it the Marburg virus?
Regardless, I would definitely give them urgent business to attend to outside the quarantine, and people they care about that need their advice, assistance, and comforting. Nothing will make them more desperate than situations entirely outside their control. Make them really want to leave and tempt them to break the quarantine, of course. perhaps this, coupled with hints that it is all an unnecessary sham, would really amp up the desperation.