would ball defend itself?

[HMT]

so... my ball python is lost. Usually he can be found near his tank, but this time he was adventurous. I've read all the other threads about losing snakes and finding them, so I'm not asking where to look or anything.

Here's my questions~
I have 5 cats, two of whom are rather small, one just under a year old. At first I was worried that they would kill him if they found him- but now I am worried that the snake might hurt them if they picked him up. (my cats usually carry toys and live animals around the house and bring them to us still living) The cats are all way too big for my python to consider "edible", but I am wondering if he would constrict around their neck if they bothered him? What exactly will a ball python do to defend itself? He's only bitten me once ever, and that was because I still smelled like mouse when I picked him up for feeding time.

Also, I'm 8 months pregnant... should I worry about any diseases or such the snake can transmit to the baby if he comes out of hiding? Lately we've had wild rodents getting into our house through the garage and chimney... found a chipmunk in our living room (near the snake tank) the snake killed and couldn't fit in his mouth just hours after he escaped. I doubt he can fit a chipmunk or flying squirrel in his mouth yet, but it is possible if he is gone for a long time that he'll return with whatever parasites and such that wild animals carry. Thoughts?

thanks,
Heidi