How long is c diff contagious?

Good question: Hard to say. We don't routinely test patients with c diff to confirm eradication after treatment, because they can still be asymptomatic carriers (test positive but feeling well). So are they contagious? Probably not. The vast majority of people exposed to someone with prior c diff don't get sick. But exposure to active c diff could lead to colonization, or even infection if on antibiotics.