How can I tell if my baby has rsv?

Severe cold symptoms. Rsv may cause a common cold in some children. However in young infants, RSV may cause much more severe cold symptoms (associated with marked nasal drainage and congestion, difficulty breathing with wheezing, grunting, retractions in the chest). If your baby is struggling to breathe, it is best to contact your doctor for her to be seen in case the infection may be due to rsv.
Getting Tested. Normally I don't do any tests. I treat them base on clinical findings, unless asymptomatic, just observe and give supportive treatment. I only run test, RSV wash when they are admitted to the hospital and for documentation. The test can come back negative 3-4 times before it turn positive, why waste the money? Test is not going to change treatment. Make child feel better.
Wheezy. Rsv is a very common respiratory virus, especially from october through march. It affects young infants, and often causes a long lasting "cold" with significant wheezing and harsh cough. If your baby has a cough and runny nose, is having trouble sleeping or eating, or sounds wheezy, see your pediatrician.
See a doctor. The baby needs to see the doctor to have their lungs listened to to evaluate if the child is wheezing. Your doctor might have the capabilities to test for it in the office or send a nasal swab to the lab to test for it.