Vonnie, I"m so sorry to hear about your pretty kitty. Here's what I found on wikipedia about cat flu.
Cat flu is the common name for a feline upper respiratory tract disease. It is a misnomer, since it usually does not refer to an infection by an influenza virus. Instead, it is a syndrome, a term referring to the fact that patients display a number of symptoms that can be caused by one or more of the following infectious agents (pathogens):
The scientific name of the causative agent is listed first; a related more common term is written in parentheses.
Feline herpes virus causing feline viral rhinotracheitis (cat common cold, this is the disease that is closely similar to cat flu)
Feline calicivirus - (cat respiratory disease)
Bordetella bronchiseptica - (cat kennel cough)
Chlamydophila felis - (chlamydia)
Avian flu can also infect cats, in which case it would be accurate to call the ensuing disease cat influenza.