My friends mum is a Jehovah Witness and won't allow her to have a blood transfusion!?

My friends mum is a Jehovah Witness and won't allow her 14 year old daughter (my friend) to have a blood transfusion because hof her religion, but my friend needs it because of some bacteria that is in her blood and needs to be taken out. I am the only one she has told this to, and I don't no what to say or whether to tell anyone what should I do, she needs this blood transfusion to sat alive!