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Testing for / Methods for Diagnosing ABV and Proventricular Dilatation Disease (PDD)

Cockatoo KrissyBy

Jeannine Miesle, MA

Academic researcher in the field of avian medicine. Member of the Association of Avian Veterinarians (AAV).

The author is indebted to Dr. Robert Dahlhausen (Avian & Exotic Medical Center, Milford, OH) for his advice and support on this paper.

Full Article: Current Research and Advances in ABV and PDD for Clinicians and Aviculturists

Clinicians often wish to rule out other diseases before they screen for ABV infection since it is possible that some of the symptoms and lesions found might be caused by another disease state.

Until just a few years ago, the only diagnostic tools practitioners had were history, radiography, and signs; thus, clinicians were often unsure of their diagnoses. In an effort to “provide practical, non-invasive screening of populations,” researchers have begun to use cloacal swabs, fecal samples, and blood samples.1 Some of these tests, however, give false positive, false negative, and inconsistent results. This makes detection and accurate diagnosis very challenging.

Standard Methods for Diagnosing PDD

In the past, a “presumptive PDD diagnosis was a systemic investigation based on blood tests, signs, cellular evidence, and radiography or CT-scans.” 2,5  

More recently, the ELISA serology test and crop biopsy have been added to locate the virus in the blood and nerve tissues.5

Today, identification of ganglioneuritis in the lymphocytes and plasmacytes (lymphoplasmacytic ganglioneuritis) through molecular PCR testing provides a definitive diagnosis of PDD.” 2

Dilated crop

Figure 4: Arrow indicates dilated crop four hours after feeding, with little or no mobility. (Courtesy S. Orosz)

Standard Testing Protocols

  • Radiographs and CT-Scans: Show the dilated proventriculus and determine motility time.19
  • Crop Biopsy: A section of crop and a prominent blood vessel are removed and examined for the presence of lymphoplasmacytic ganglioneuritis in crop tissue.1
  • ELISA (enzyme-linked immunosorbent assay): This serology test looks for immunological exposure to specific ABV antigens. 1
  • PCR—Molecular Diagnostics: These are genetic DNA tests which will detect shedding of the Avian Bornavirus.1 These tests are the most accurate of all.
  • Anti-ganglioside Antibody test: This test looks for antibodies to the virus in the blood. It gives definitive proof of the presence of the Avian Bornavirus.
  • Researchers test for the eight known ABV genotypes.


Figure 6: Signs of self-mutilation in an African Grey (Courtesy R. Dahlhausen)

Guidelines for Current Diagnosis of PDD:

  • A bird is considered negative for PDD if he is healthy, has had repeated negative blood tests, and has had no contact with any other ABV-positive birds.
  • A bird is considered positive for PDD if he is ill with clinical symptoms, has had blood tests which are positive for ABV antibodies, and the results are confirmed by PCR.
  • A bird that is ill and suspected of having PDD is considered free of ABV if the serology is negative. He has probably not contracted the disease, and the PCR should validate that.
  • A bird that is clinically healthy but serologically positive is considered a carrier of ABV. If repeated PCR testing results are negative, he may be considered “clean.” 5

Full Article: Current Research and Advances in ABV and PDD for Clinicians and Aviculturists

If more in-depth information is desired, please contact the author through Avian Web.

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