We don't really have any way of knowing who is and isn't infected. But who's been left alone with Nemesis and provided ample oppritunity for infection? All you can really do is ask yourself who has been captured and then needed be rescued.

so uhhhh perhaps elaine, molly, murphey, thomas, ivy, marcone, mortimer, georgia, andi, justine, mac, sarissa...

oh yeah, Christos made a point of locking up nearly all the younger wardens plus anna during changes.