Juszczyk (illness) didn't practice Friday, Nick Wagoner of ESPN.com reports.
The veteran fullback popped up on San Francisco's injury report Friday as a non-participant in practice due to an illness. It's unclear if the ailment is severe enough to impact his availability for Monday night's matchup against the Lions. Juszczyk typically sees limited touches on offense, though he could get a few more than usual in Week 17 with Christian McCaffrey (knee), Jordan Mason (ankle) and Elijah Mitchell (hamstring) all sidelined.