RSV, which generally circulates from late fall into the early spring, is out there with a myriad of other stuff floating around right now: Human metapneumovirus (hMPV), adenovirus and parainfluenza, all common respiratory viruses, and pertussis, the bacterial disease that causes whooping cough.

CNN: Baby ill? It might not be the flu

Ferrets are often used in flu research because the animal's respiratory tract responds to flu viruses in much the same way as a human's.

CNN: CDC: U.S. may need 600 million swine flu vaccine doses