One of my rats just died saturday night of what seemed like some sort of infection or cold

My question is if it was pneumonia or some sort of infection like that, is my other rat at risk of catching it? i was doing some research and am getting a lot of info about rats getting this type of ailment a lot and that she may have been born with it. my other rat is acting normal, not breathing heavy or anything. We also have a cat. Are diseases transmittable from rats to cats at all? or to humans at that?

Sounds just like what happened to my other rat a few weeks ago. (I posted a question about getting another rat). What you are thinking of is Mycroplasma (I think that's how it's spelled). As far as I know rats and cats cannot pass illnesses like that to humans or vice versa. I also don't think the cat made the rat sick. These things just happen sometimes. If your other rat appears normal it's probably fine. You could take it to the vet if you like, just to get a clean bill of health. So to answer your question, what most likely caused your rat to die is not transmittable to humans or cats I would assume. I'm sorry for the loss of your rat friend and consider, in time, to get a buddy for your other rat. Take care!