Avian Bornavirus and Proventricular Dilation Disease (PDD)
Avian Bornavirus is a virus that infects the nervous system of birds. In 2008, two research teams independently reported the presence of Avian Bornavirus in birds diagnosed with Proventricular Dilation Disease (PDD), also known as Macaw Wasting Disease. Later studies found that birds infected with Avian Bornavirus can develop PDD. As a result of this and other work, Avian Bornavirus is recognized as the causative agent of PDD.
The Disease
Avian Bornavirus infects nerve cells and the clinical signs of the disease result from the bird’s immune system interfering with the normal function of these infected nerves. The disease often manifests as a series of gastrointestinal intestinal problems. Intestinal paralysis and general degradation of intestinal function eventually result in death by starvation. The disease can also cause a host of neurological symptoms, including depression, tremors, loss of balance and coordination, blindness, and seizures, which can also lead to death.
Infection and Transmission
How birds normally become infected with Avian Bornavirus is still uncertain. Infected birds shed the virus in droppings and feather dander, thus transmission is most likely from exposure to the virus through these sources. Birds infected with Avian Bornavirus can remain healthy for many years, even decades, before becoming sick. Unfortunately, this means an entire group of birds can be placed at risk for the development of PDD well before the initial infection is detected.
Development of a Promising New Avian Bornavirus Vaccine
There is currently no treatment available for PDD. However, in 2014 researchers led by Dr. Ian Tizard of the Schubot Exotic Bird Health Center at Texas A&M University successfully developed and tested a new vaccine intended to protect birds from PDD. The vaccine is made from a recombinant Avian Bornavirus nucleoprotein. To date, the vaccine has been tested in Cockatiels and has been found to prevent the development of PDD.
In the vaccine trials, three groups of cockatiels were used:
Group 1 - vaccinated, then one month later infected with Avian Bornavirus;
Group 2 - infected with Avian Bornavirus, then vaccinated one month later; and,
Group 3 - infected with Avian Bornavirus, but not vaccinated.
Results of the study were:
Birds vaccinated before being infected (Group 1), did not develop PDD and survived.
The vaccine did not protect birds if given after infection (Group 2).
All groups became infected with Avian Bornavirus and virus was shed in their droppings.
While the current vaccine does not prevent birds from becoming infected with Avian Bornavirus, the results suggests that if the vaccine is given before the birds are infected, it has the potential to protect at least some species from becoming sick with the disease PDD.
The Future
Further studies of the vaccine involving other parrot species (Macaws, Amazons, African Grays, Cockatoos, etc.) are planned.
I'm hoping I just read too much into that.
