Originally Posted by MageB420666

And it doesn't matter how far away from the original desease carrier you are in the chain, what matters is if your after the point in the chain where the next person doesn't catch the desease. The probability of you getting the desease from the originator of the disease in the chain is the same as if you slept with some one ten steps down the chain, so long as the disease was transmitted through those ten steps. And if there is a break where a person in the chain does not get the disease then the risk of getting that disease from that person goes to zero, assuming that it is a chain scenario and not a web, and that the person did not already have the disease.