Are there many cases of hiv or hepatitis c being transferred by a toothbrush? is there any cases?

Prob rare: Hepatitis c, especially, can exist on environmental surfaces for over a week, so objects that contain very small amounts of blood could theoretically be risky. Household members have been documented to get hepatitis c from each other, but people likely share lots of things so the risk of any one thing, like toothbrushes, would be hard to figure out.

Blood on it?: Hiv & hepatitis c are transmitted by contact with an infected persons blood. No blood = no transmission. However think of all those virus and bacteria that can be passed on shared toothbrushes & other personal care items. I certainly can't imagine sticking a toothbrush in my mouth that has someone's morning crud all over it.