Any bird may be affected by Aspergillus species, but it is most commonly associated with birds of prey and with parrot species that are taking a seed-based diet.

C. albicans can be a primary gastrointestinal pathogen, especially in finches, but it is more frequently secondary to another problem. 

Psittaci is a zoonotic organism, meaning that it can be passed between different species -including between animals and humans.

Megabacteria is actually a yeast organism called Macrorhabdus ornithogaster, or avian gastric yeast.

There are many strains of adenovirus, and the vast majority are adapted for a specific host species so often cause subclinical disease, meaning illness may not be obvious. 

Herpes viruses belong to an enormous family of DNA viruses – there are over 100 different strains and they affect most species.