I wouldn't necessarily 'freak out' about this particular exposure, however, I always recommend testing.

Familial/horizontal transmission among family members in a household is fairly rare. In the few instances where it has occured, it is thought that the sharing of toothbrushes or razors may have been the cause of transmission -- though it hasn't been proven scientifically. So, sharing razors or toothbrushes with someone with Hep C (or anyone really) is obviously not a smart thing to do!

In this particular instance, it seems a very low risk -- first of all, there would have to be blood, or trace amounts, on the toothbrush, and that blood would have to find its way into the bloostream of your child, which could easily not have occured. If he wasn't 'brushing' with the toothbrush there is less of a theoretical chance of transmission.

But, I would, as part of your childs next checkup, speak with your doctor about this possible exposure and ask whether or not testing is recommended. Even if it isn't recommended, if it puts you at ease, insist on a HCV antibody test. (You need to wait at least 3 months after the exposure for the test to be accurate)

Hope this helps