My brother was bitten by a dog in mexico, until he get the rabbies vaccine what precautions he should take to not infect the family members?

Don't bite: Rabies is a virus that is found in the saliva of infected animals. I don't think and haven't seen it be transmitted from a person to another. He should have gotten the rabies immunoglobulin and vaccine as soon as possible if there was a concern about rabies. If the dog is able to be found it should be evaluated by a veterinarian or euthanized to be studied. I hope your brother is doing well.