Can birds get infected by contact with viruses transmitted by humans?
In human and birds, generally speaking, there are three main reasons bacteria are able to cause an infection.
1. Some bacteria species are just extremely virulent and are able to attack successfully a strong and healthy immune system.
2. Large-dose exposure to opportunistic bacteria is another common cause. Good sanitation does usually prevents this.
3. The most common cause is an infection by opportunistic bacteria due to a reduced immune response. This can happen in times of stress, poor nutrition, or concurrent disease conditions.
When humans get a cold, then this is often caused by a viruses. These viruses do not, itself, readily infect our birds. The avian body temperature is too high for most viruses to do well. This is, in fact, why we get a fever when infected by viruses, it is one of our body’s ways to fight them. However, we do also harbour a number of bacteria found naturally in our mouths, sinuses and eyes, that can infect birds, if given the chance, in particular via the first and second route as outlined above. These bacteria include, but are not limited to, other species of Streptococcus than the one that infects us, that we carry around all the time without getting infected. But these ones can potentially infect birds.