HI I presume you are speaking of chicken pox. Yes her unborn 16 week old baby is in danger assuming she has not had chickenpox vaccine. If she develops chicken pox there is a small possibility (1%) that the baby may develop serious birth defects. If I were her doctor I would first advise her to stop working in that house and check her blood to know if she is immune for chicken pox infection. (Chicken pox is a common childhood infection which causes mild infection which you may not be remembering. The infection provides lifelong immunity) If she is not immune and she is working in that house for less than 10days then I would give her varicella Zoster immunoglobulin. I would keep watch for three weeks to find out at the earliest if she develops rashes and treat it. I will give her varicella zoster vaccination after delivery. I hope I have answered to your satisfaction.