From the final 10-episode arc of Deep Space Nine we learned several things about the Morphogenic virus afflicting all of the Changelings.
(major spoilers ahead if you haven't seen the end of DS9)
- Odo was the carrier of the virus
- Section 31 initially gave the disease to Odo back in 2372 (Season 4 of DS9)
- The virus was passed on by linking
- Frequent shape shifting caused the disease to progress more rapidly
- Odo cured all of the Changelings when he rejoined the Great Link.
But in the Season 7 episode Chimera, Odo linked with the Changeling Laas several times. Presumably, the virus was passed to Laas at this time, although this was never stated definitively in the series (which is confirmed by the earlier link about the virus)
Odo was unaware he was carrying the virus when he linked with Laas in DS9: "Chimera". Whether or not Laas developed the disease, and whether or not he was able to receive the cure, are unknown.
Since Laas did not want to join the Great Link, it seems likely he was still out searching the galaxy of the remainder of the 100 (only 98 to go). As such, he would not have been cured when Odo cured everyone else.
Did he ever get cured? Or was he left to die? Because seemed to enjoy taking different forms, it seems likely that if he was afflicted, he would have begun to deteriorate very quickly after leaving DS9.
Was the fate of Laas ever covered in any other material (canon or not)?