ASFs can be a miracle when a BP goes off feed. My Rayanne would eat a rat every 2-4 months as she wasted away. It was just enough that I didn't resort to force-feeding. Eventually I found she'll eat medium-sized dark-colored ASFs like candy, and she's bouncing back wonderfully.
How's Nerissa's weight (she was at 1970g in Oct 2009 if my records are correct), and have you dropped temps for the season? I'm wondering if she just started a normal winter fast. Some of mine are starting to fast for the winter, but I may be further north than you are.
My records indicate Narissa ate only rats here, so the ASFs probably blew her mind having only smelled them from a distance before, assuming an animal's native food tastes better than the foreign Norwegian rats we generally feed them.