Why Is Scabies Not Treated Before The Symptoms Show Up?

My daughters been diagnosed with scabies. I'm 7 mths pregnant. My oby won't treat me until in break out with visual symptoms. I swear I feel something crawling and butting me under my skin periodically in my hands and feet ankles n knees. I doont understand why I wouldn't treat before the blisters/pimples appear. I don't want to pass it back to my 4year old or my three year old daughter or my fiancé. Is it totally necessary for me to wait until I actually break out?