Dave J. Rupiper DVM, Dipl. ABVP East Petaluma Animal Hospital 1420-B South McDowell Blvd., Petaluma, CA 94954 Phone: (707) 765-9098 Fax: (707) 765-2984 Web: EPAH.net Avian Polyomavirus History Avian Polyomavirus (APV, Papovavirus, Papillomavirus) was first identified in budgies, then in other psittacines, and most recently has been shown to cause disease in finches. Signs APV can infect psittacines of all ages but nestlings and juveniles are most susceptible. Young psittacines may have slow crops, reduced feed responses and depression. Once these birds begin to show clinical signs, subsequent bruising of the skin and muscles may occur, as can death, within hours to days. Adult budgies may have abnormal feather growth, heart disease and liver damage. Adult psittacines, infected as juveniles, may carry the virus and die suddenly when stressed days, weeks or months later. Some psittacine species, such as Eclectus parrots, seem more susceptible as juveniles, as well as adults, and may succumb to the disease. Diagnosis Birds which die suddenly from Polyomavirus and are necropsied (autopsied) often show changes suggestive of the disease. Therefore, all dead birds should be examined. Histopathology (microscopic examination of the tissues) helps to identify the "footprint" Polyomavirus leaves in the tissues. A DNA test specific for Polyomavirus, which can be performed on a vent swab or blood sample, is available but it is only diagnostic if birds are shedding the virus or viremic. Other tests which have been developed are not yet commercially available. A positive result means that viral DNA was detected, it does not mean that the bird will develop active disease. Transmission Polyomavirus can be passed from the hen to the egg, but most infections are spread by direct contact, feather dander and fecal dust. Exposed hens may develop protective antibodies which are passed on to nestlings and may provide temporary immunity. Conversely, offspring from unexposed hens are at higher risk of infection since they lack protective antibodies. Polyomavirus is held in the organs of carrier birds and is shed in the droppings when they become stressed. Infectivity of APV is reduced by disinfectants such as bleach, nolvalsan, virkon-s and wavicide. Treatment There is no treatment available for APV infected birds. Control is acheived through testing and isolation of all positive birds and vaccination. Since shedding is intermittent in carriers, identification of infected adults can be difficult. Control in an outbreak is maintained by disinfection of handfeeding utensils, incubators and brooders and by vaccination. A vaccine has been developed to protect non-infected psittacines. Birds can receive the first vaccine as early as 35 days of age and again two weeks later during an outbreak but 45 days of age is recommended for the first dose. A third vaccine is recommended if birds are vaccinated at 20 days of age. Older birds receive two vaccines 2-4 weeks apart then one booster annually. Both negative or positive adult and juvenile parrots can be vaccinated. Research has shown that carrier birds may develop kidney problems from the vaccine but the benefits clearly outweight the consequences during an outbreak. Most vaccinated birds will develop a skin reaction which should resolve without treatment in 3-6 weeks.