Comment by saghm

I think the idea is that a raccoon you encounter is conditionwlly more likely to have rabies just based on the fact that you've encountered it. My understanding is that rabid racoons are less nocturnal and far less likely to feel the need to run or hide from humans.

It's possible they botched the grammar here a little, but my interpretation is saying that if you look at the group of raccoons that allow themselves to be exposed itself to a human or pet (rather than avoiding us, which is not that hard for them to do it they want), around 10% of them have rabies.