Exactly…the CDC page on Rat Bite Fever says it's very rare to see a fatal case, and that usually there are preexisting conditions. It also said that the fever usually is around 103-104….when I got fevers that high it was a trip to the doctor when I was young. That's bordering on dangerous temps for a human, so I don't see why the family didn't go to the doctor sooner, or at least give the kid an antipyretic.
And if we really studied the number of possibly fatal diseases that live on our skin, on our vegetables, and on our cats and dogs (E coli or Chlamydia anyone??) we would be living on the moon to avoid them all. I think it's overzealous for the family to sue PetCo for this…do we even know if the bacteria that causes this is "contracted" by the rats, or is it a member of their natural flora??
Oh, and OsirisRa, what field are you in that you study Infectious Diseases??