How does it affect the toddler

Okay this is going to sound bad and I feel bad but I can't help it. I babysit my friends son. She sleeps around A LOT when she was pregnant she wouldn't get the std tests beccause she said she didn't want to know if she had anything. She has told me about sores down there before. If she has herpes does her son? I always wash my hands after touching him because he grosses me out. I know that sounds awful. Our kids are 6 weeks apart and I'm scared he's going to catch something from him. Last night she brought her son over while he might have poison ivy! Wtf is wrong with her?! Ugh I told her obviously I'm not watching him until you make sure the rash isn't contagious but I'm just so disgusted. I feel bad for the boy but at the same time I don't even want to touch him. I know I need to tell her I just cant watch him anymore but she doesn't really have anyone else to watch him. Help! Idk how what to do.