It is possible for rats to contract rabies and transmit the disease to other animals and humans.
For this reason, be wary of a rat that exhibits aggressive behavior such as biting.Foaming from the mouth and acting disoriented are also possible signs of rabies.
If you are bitten by a rat, you should capture and kill the rat if possible, so that it may be tested for rabies.
Otherwise, you may need to go through a series of rabies shots in order to protect yourself from infection, since once symptoms of rabies manifest it is usually too late to counteract.