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Angel has four favorite sayings: "Hello," "I love you," "I'm Angel" and "What you doing?"
The white-crested cockatoo recently sat on top of a wooden bird block fluffing her soft feathers inside the Schubot Exotic Birth and Health Center at Texas A&M University.
At 19, she's healthy. If she stays that way, she could possibly outlive her 49-year-old owner. Cockatoos typically live to be 60.
But if Angel were to be infected with proventricular dilatation disease (PDD), a contagious neurological disorder affecting captive birds worldwide, experts say she would most certainly die.
"I'd be devastated," said Angel's owner, Dr. Sharman Hoppes, a researcher and clinical professor at the Schubot Exotic Birth Center, as she kissed her pet bird's neck.
She owns seven other birds, all of which she said could one day be infected with PDD.
For 30 years, researchers and avian veterinarians have tried unsuccessfully to discover the cause behind PDD. According to experts, it is a difficult disease to diagnose and can lead to the unnecessary euthanasia of large, rare and expensive birds.
But after spending two years and investing $200,000 on PDD studies, a team of 10 veterinary medicine and biomedical science researchers at Texas A&M have not only found a proposed causative agent of the disease, but also created a one-of-a kind test that screens for the disease.
Though the test is a major breakthrough in understanding the mysterious disease, the A&M researchers said the mode of transmission and how to kill the virus are still unknown.
PDD is a wasting type disease that progressively causes destructive, inflammatory changes in the brain and destroys the neural system to the bird's forestomach, resulting in slow starvation.
Hoppes said PDD is frequently misdiagnosed and can have an incubation period of up to a decade. It can affect all birds, but parrots such as African greys, macaws and cockatoos seem to be the most common.
Symptoms include erratic and unusual head movements, spasms and seizures, lack of balance, and regurgitation, she said.
Ian Tizard, PDD research team leader and professor of exotic bird health and professor of immunology at Texas A&M University College of Veterinary Medicine and Biomedical Sciences, said the disease is fairly common and is the "major single disease issue affecting pet birds right now."
To understand its global affect, Tizard described how Spix macaws, one of the most endangered species in the world, may go extinct because of the disease.
Tizard said there are fewer than 70 Spix macaws left in the world. About five of the 60 Spix macaws residing in an aviary at the Al Warbra Wildlife Preservation in the Arabian Gulf state of Qatar have died of PDD, he said.
The disease's origins are unknown and there is no cure, experts say.
But thanks to the team of researchers at Texas A&M, steps toward understanding the complicated disease are starting to surface.
"No one knew if [PDD] was bacterial or viral or some type of immune mediated disease," Hoppes said. "Within the last 6 months we have determined that it is most likely of a viral ideology, a Borna virus."
By using a technique called western blotting, Itamar Villanueva, a graduate student and research member at the Schubot center, developed a test in January 2008, after working on a vaccine for influenza in chickens. The test, which Villanueva said was created by chance and out of curiosity, screens a bird's blood sample for the antibodies produced in response to a specific antigen of avian Borna virus (ABV), the most likely causative agent of PDD.
"One day I got a crude brain sample after they did a necropsy -- an autopsy for animals -- on a bird that died of PDD," he said. "I took a chunk of brain, ran it on the gel, formed the western blot and it came out positive. I tested a bird that didn't die of PDD and it came out negative."
Villanueva said if the test is positive, it doesn't necessarily mean the bird has PDD, but that it may be at risk of developing the disease sometime in the future. PDD can have an incubation period as long as a decade, he said.
Villanueva said the test is about 90 percent accurate and is a safer, cheaper alternative to crop biopsy, another test to detect PDD. Crop biopsy is an invasive surgical procedure that puts the bird's life at risk by removing a piece of a bird's crop, which is an expanded portion of the alimentary tract used for the storage of food prior to digestion, to examine lesions under a microscope. It is only about 60 percent accurate, he said.
Villanueva said his test has already gained national and international attention from a small community of people engaged in exotic bird practices, adding the research team gave their testing method to a group of researchers at the University of Utrecht, a veterinary school in the Netherlands.
The test is in the works of being patented and is being temporarily offered for free to bird breeders and veterinarians in the country to test its accuracy. Tizard said each test is valued at $100, but A&M will soon offer a different test that can find the virus in bird droppings for $30.
Tizard said now the team will work diligently on finding a treatment and a vaccine. They are also working with bird aviators and using management techniques to isolate infected birds from uninfected birds, trying to clean colonies and prevent spreading of the disease, he said.
"We are testing anti-viral drugs on naturally infected birds to see if we can find a cure," Tizard said. "It's nice to have identified the cause of the disease, but it's practical to see what can we do for the bird now."
