The other year at Halloween Horror Nights, they had a quarantined area that was called "The Thing : Assimilation" which was based on an alien that could assimilate through a virus, into anything it came in contact with if I am not mistaken.
Inside of it, you may want to use a lot of clear or white plastic, that is generally used at such quarantine zones.
Having someone outside that wears a protection suit, or inside the first room, would look neat ^_^
Splatting blood on the plastic is a neat effect too, combine that with random things going on within the asylum and you have yourself a neat haunted house. The general idea to have patients going crazy in some areas, and doctors going crazy in others.
You can get a lot of medical props for very cheap from Halloween Stores online and actual stores. Scrubs can be purchased fairly cheap from actual scrub stores online and real stores (Scrubs are what doctors/nurses wear). Add blood, a few hair-nets and you should be in good shape ^_^