Lecture 1 Styles

Psittacid Herpesviruses and the Link to Mucosal Papillomatosis and Bile Duct Carcinomatosis

Presenting Author: Daryl Styles, DVM, Dipl ABVP (Avian),

Schubot Exotic Bird Health Center, Texas A&M University, TX

Interpretive Review and comments by Dr. Nemetz:

Dr. Daryl Styles proved definitively that the mucosal papillomas seen in Neotropical species (South American), especially macaws and amazons long believed to be "viral papillomas" are in fact caused by a herpes virus. He also demonstrated that this herpes virus was the same etiologic agent that causes Pacheco's viral disease. The BIRD Clinic has diagnosed many of these cases over the years. The recurrent pattern and behavior of the cloacal growths, in Dr. Nemetz' opinion, never supported the idea of a papilloma viral etiology. This doubt was substantiated by the fact that early autogenous vaccines and various surgical procedures failed to show long term improvement. Some birds infected with this herpes virus presented with related lesions in other parts of the body and has been shown to have a relationship with a form of liver and/or pancreatic cancer. It is a credit to Dr. Styles and his investigative group for this excellent presentation.

This herpes disease process usually presents as a bleeding mass extending from the vent area or pale nodular growths around the choanal slit or glottis. It often confuses owners and veterinarians, as the symptoms are variable in degree and in presentation with only seasonal presentation. Other cases present for recurrent cloacal bacterial/yeast infections and individual birds can carry this virus asymptomatically for decades.


The cloacal/choanal "papilloma" growths in South American birds are now confirmed to be the representation of the herpes virus also responsible for Pacheco's disease outbreaks. If you own multiple birds or have a breeding facility that has one of these infected birds, they should be immediately isolated. The mass should be biopsied to confirm the diagnosis by histopathology. If this contagious, potentially deadly disease is confirmed, the long-term prognosis and risks to your other birds should be seriously discussed with your avian veterinarian.