Wrath of the Prophets (Star Trek Deep Space Nine, Book 20)
When a fatal disease spreads over Bajor, threatening the entire planet with extinction, Captain Sisko must accept aid from an unexpected source: Ro Laren, Starfleet officer turned Maquis renegade. Major Kira and Ro reluctantly join forces to track the alien plague to its source -- even as the disease claims new victims onDeep Space Nineitself.  Dr. Bashir struggles to find a cure, but the secret of the virulent invader may hide deep in the shadows of Dax's past.