Old World Aviaries

Investigators: Lynn Cassone, Robert Moore, David N. Phalen, Karen Russell, Darrel Styles, Ian Tizard, Karen Snowden, Elizabeth Tomaszewski, William Wigle

Pacheco's disease virus and related herpesviruses

What is the significance of this work?

Pacheco's disease (PD) is a disease caused by a herpesvirus that has impacted captive parrot populations since the 1970's. Single outbreaks of this disease have killed hundreds of birds. While this catastrophic level of mortality is unusual, valuable breeding birds and beloved pets continue to die from this disease every year. It has long been suspected that some parrots are carriers of this virus, but which species were most likely to the carry this disease was not known and an assay capable of detecting these birds was not available. Having an assay that is able to detect carrier birds would allow these birds to be isolated away from other birds that are susceptible to infection.

Our objectives

• Determine the genetic sequence of herpesviruses that cause PD. Use this information to select a set of DNA probes that can detect all pathogenic PD viruses.
• Determine if other nondisease-causing herpesviruses are found in birds and to determine their genetic sequences. From this data, verify that the DNA probes that we develop only detect disease-causing herpesviruses.
• Use the DNA probes to screen the lining of the mouth and the cloaca and blood for the presence of PD viruses.
• Determine if a single sample or repeated samples will be able to detect birds carrying the PD viruses.

Accomplishments to date

We have purified and sequenced portions of the Pacheco's disease virus. From this we have helped to develop and validate a test that can detect these disease-causing viruses.

• We have shown that the viruses can be detected by analyzing swabs and blood in combination, and that birds most likely to be the source of Pacheco's outbreaks can be detected, in most cases, with 2 samplings one month apart.
• Our initial work suggests that the infection cycle can be broken by incubator hatching eggs and raising chicks in isolation from parent-raised birds.

Internal papillomatosis

What is the significance of this work?

Internal papillomatosis is still a fairly common disease of Amazon parrots, macaws, and conures. It causes wart-like growths of the oral cavity and vent. This is a chronic disease. While it does not kill the bird right away, this disease causes the bird considerable discomfort and eventually can lead to death. There is also an unexpectedly high incidence of cancer of the liver and pancreas in these birds. Clinical evidence strongly suggests that this is an infectious disease.

Our objectives

• Determine the cause of this disease.
• Find a way to detect birds that are infected with the agent that causes this disease.

Accomplishments to date

• We are currently pursuing the possibility that other viruses may also be present in these birds and may be associated with this disease.
• In our research colony, we are monitoring the natural progression of the diseased tissues in these birds. It is clear that the warts are not static, and that the lesions come and go in most birds. This will be important information if we are to do treatment trials.

Megabacteria

What is the significance of this work?

Our objectives

• Identified the so-called megabacteria organism found in budgerigars.
• Determine if this organism is the same organism that is present in other species of birds.
• Determine if transmission can be interrupted by incubator hatching eggs.
• Evaluate new drugs to find a more effective, practical, and less expensive method for treatment of this organism.
• Determine the actual potential this organism has for causing disease.

Progress to date

• We have identified this organism as a specific fungus.
• We are evaluating the management technique of incubator hatching eggs and raising chicks in isolation as a means of breaking the infection cycle.
• Trials with drugs not previously used to treat this organism are also underway.

Avian tuberculosis

What is the significance of this work?

Avian tuberculosis is an uncommon, but ever-present, threat to cage birds. It has been a particularly difficult disease to recognize in early and even advanced stages of infection. It has taken a severe toll on grey-cheeked parakeets and the red siskin. It has also been a serious problem for zoo collections and captive breeding programs of endangered species of birds. A diagnostic assay or assays that could detect infected birds before the onset of clinical signs would be of great value in controlling this disease.

Our objectives

• In collaboration with investigators at the University of California at Davis, we are seeking to develop new diagnostic assays to identify birds infected with avian tuberculosis.
• Using these assays and specific management techniques, we will attempt to break the avian tuberculosis infection cycle that occurs in the red siskin.

Progress to date

• Currently we are looking at the ability of an antibody assay to detect infected birds. Initial work suggests that this will be a useful assay, but to detect all infected birds, it will have to be combined with other assays.

Avian polyomavirus

Significance of this work

There are few bird owners who have not heard about this virus or been directly impacted by it. This virus routinely kills nestling parrots, particularly macaws, conures, and Eclectus parrots. Investigators at Texas A&M have a long history in studying this virus. The dynamics of this viral infection in budgerigar aviaries has been investigated here. We have also verified the suggestion that older experienced budgerigars that were previously infected with APV can be used for breeding and produce APV-free young. We have shown that the virus infecting budgerigars is the same as virus that infects other species of parrots. We have shown that the kidney disease caused by this virus is the result of immune complexes, information that some day may provide an insight into preventative treatment of this infection. We have also done the only definitive study to show the dynamics of this viral infection in parrot nurseries. We have shown that this virus spreads rapidly between birds, so that often by the time of the first birds death, most if not all, in-contact chicks are infected. This same study showed it is necessary to test both blood and oral swabs combined with cloacal swabs to detect all birds shedding virus. Our work also showed the expected duration of virus shedding in recently infected nestling and adult birds.

Our objectives and progress to date

• Characterize a new strain of avian polyomavirus that kills nestling cockatoos. We are currently working on determining how this virus does what it does and what its relationship is to other strains of the avian polyomavirus.
• We are currently determining the sequence of avian polyomaviruses from several nonparrot species of birds. With this information we will be able to tell what the relationship of these viruses have to those that cause disease in parrots.

Great-billed Parrots

Significance of this research

Although rare in aviculture, this parrot is facing the possibility of extinction in the wild. It has been the impression of great-billed owners that birds kept outside in the south are at high risk for a disease and death from an as yet undetermined cause.

Our objectives

• Determine if there is an unusually high incidence of death in these birds kept in the south.
• Determine what the risk factors are for disease in these birds.
• Examine birds that have died in an effort to determine their cause of death.

Progress to date

• Using a survey of great-billed parrot owners we have shown that great-billed parrots housed in the southern United States are dying at an unusually high rate.
• Certain risk factors have been identified, but a specific a specific agent causing these birds' deaths has not been identified.
• Necropsy records from pathologists across the country have been collected and are being reviewed.
• We are asking that anyone losing a great-billed parrot to submit the body to us for necropsy. Please call 979-845-4300 for instructions on how to get the body to us.

Conservation

The Schubot Exotic Bird Health Center funds several other projects that relate to wildlife and conservation. For more information on these projects please check the Schubot Exotic Bird Health Center's web site. The Schubot Center

Where do we need the most help?

In order to continue this diverse and aggressive program into issues that significantly impact aviculturalists and pet bird owners, we will need continued support from the bird-owning public. The three projects that we particularly need support for are the herpesvirus, internal papillomatosis, and megabacteria work.

We can assure you that this money will be used to leverage other funds and will be used frugally to give the donor the biggest possible bang for the buck.

Thanks!!!

To the many of you who have already donated money to our program or helped to raise money for our program, we are greatly appreciative.

Sincerely,

Dr. David N. Phalen.