To put your mind at ease, humans cannot transfer colds or flu viruses to their birds.
There are a couple of viruses that we may pass on to our birds but these are a rarity.
There is more concern about what we can give our birds through our saliva. We are not advising you
to stop kissing your bird, just be more careful.
Our saliva contains gram-negative bacteria which are not present in the avian family making them very difficult for our birds to overcome illness from this bacteria.
Since all mammals carry gram-negative bacteria in their mouths, even a friendly lick (or an unfriendly bite) is dangerous. Our 4-legged pals lick themselves daily spreading gram-negative bacteria on their bodies and paws. Even a scratch from one of those paws is a major problem. If your bird is ever bitten or scratcherd by your other pets, immediate veterinary attention is necessary.
In order to find out whether a bacteria is gram-negative or gram-positive, a dye called crystal gentian violet is applied to the sample. Gram-negative bacteria, with its thicker cell wall, turns pink/red while gram-positive retains the color of the crystal violet stain.
Many pet birds will imitate their humans and will sneeze or cough along with them. This could be just a playful action. Of course, if your bird shows signs of illness – not eating, diarrhea, difficulty breathing, blocked nares and so on, s/he should be seen by the vet immediately.