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AVIAN POLYOMAVIRUS: MY THOUGHTS

David N. Phalen, D.V.M., Ph.D.
Dipl. ABVP (Avian)
Former Assistant Professor, Zoological Medicine Section
Department of Large Animal Medicine and Surgery
Texas A&M University
College Station, Texas 77843
Now resides and works in Australia

CONTENTS

  1. INTRODUCTION
  2. AVIAN POLYOMAVIRUS: A DEFINITION AND HISTORY
  3. AVIAN POLYOMAVIRUS DISEASE
  4. INFECTION VERSUS DISEASE
  5. APV INFECTION AND DISEASE IN ADULT PARROTS; THE PBFDV CONNECTION
  6. ARE CAIQUES MORE SUSCEPTIBLE TO APV INFECTION EVEN AS ADULTS, THAN OTHER PARROTS?
  7. TESTING
  8. THE APV VACCINE; POSSIBLY A TOOL, NOT A PANACEA
  9. DISEASE PREVENTION
  10. CONTROL OF APV OUTBREAKS
  11. APV INFECTION AND DISEASE IN NONPSITTACINE BIRDS
  12. CONCLUSIONS
  13. REFERENCES

INTRODUCTION

The avian polyomavirus is one of the most significant viral pathogens of cage birds. It results in substantial economic losses for aviculturalists and pet store owners each year. The biology of this virus is complex and as a result veterinarians and aviculturalists alike are often very confused about how to best prevent this virus infection and once confronted with it, how to minimize its impact. This confusion is exacerbated by the current debate that is on going in the research community about the nature of this virus and its control. The two sides of this debate are represented by Dr. Branson Ritchie and members of his research team at the University of Georgia, on the one hand and on the other by Dr. Jack Gaskin at the University of Florida, Drs. Bob Dahlhausen and Steve Radabaugh at Research Associates in Ohio, and myself. Dr. Ritchie has used many forums to discuss his views and feels strongly that vaccination is an important and economically feasible means of control of this disease. Dr. Gaskin, in a letter to the editor of the Journal of Avian Medicine and Surgery has expressed some serious reservations about the usefulness of a polyomavirus vaccine.15 The issue of testing and its value and which test to use has also be a source of contention. It is the purpose of this document to address these issues, both for the aviculturalist and the veterinarian. I feel that his article is timely, as our knowledge biology and behavior of this virus has grown significantly in the past few years.

AVIAN POLYOMAVIRUS: A DEFINITION AND HISTORY

The avian polyomavirus was first recognized in the early 1980's in the southeastern and southcentral United States 4,9,10 and in Ontario, Canada in budgerigars.2,3 It was called the Budgerigar Fledgling Disease Virus. It was found to be a nonenveloped, DNA virus and based on its size, shape, and DNA content it was classified as a papovavirus.2,3,4,9,10,49 The Papovaviridae contain two very different virus families, the papillomaviruses and the polyomaviruses. With further investigation, it was determined that the Budgerigar Fledgling Disease Virus is a polyomavirus. 26,29,57 Subsequently, the virus was found to infect many different species of psittacine birds (parrots) and thus it is generally the convention to call it the avian polyomavirus (APV).5,17,20,35,45 APV is wide spread and can be found in most countries of the world where psittacine birds are raised.29,31,32,59,61 As will become clearly apparent, generalizations about this virus cannot be made and over simplification about the issues of infection and disease, while convenient, are often misleading.

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