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Infection in wild and captive-raised birds is widespread. All psittacine birds and many other species of birds are susceptible to infection. Disease is generally limited to Budgerigar and lovebird nestlings and hand-fed nestling parrots. It is seen less commonly in Amazon parrots and cockatoos.

Infection in wild and captive-raised birds is widespread. All psittacine birds and many other species of birds are susceptible to infection. Disease is generally limited to Budgerigar and lovebird nestlings and hand-fed nestling parrots. It is seen less commonly in Amazon parrots and cockatoos.

APV is a non-envelopped, icosahedral virus that has a circule double-stranded DNA genome. There is little evidence to suggest any host specificity of the virus.

APV is a non-envelopped, icosahedral virus that has a circular double-stranded DNA genome. There is little evidence to suggest any host specificity of the virus.

==Epidemiology==

==Epidemiology==

Infections in susceptible non-Budgerigar species that are of the appropriate age result in a rapidly fatal disease, but slightly older nestlings survive and shed virus in faeces and possibly through feather dander for up to 16 weeks. The birds are important sources of infection for other birds.

Infections in susceptible non-Budgerigar species that are of the appropriate age result in a rapidly fatal disease, but slightly older nestlings survive and shed virus in faeces and possibly through feather dander for up to 16 weeks. The birds are important sources of infection for other birds.

In Budgerigars, shedding is believed to continue for '''up to 6 months'''. Concurrent APV and Psittacine Beak and Feather Disease virus infection may permit persistent shedding of APV.

In Budgerigars, shedding is believed to continue for '''up to 6 months'''. Concurrent APV and [[Psittacine Beak and Feather Disease]] virus infection may permit persistent shedding of APV.

Infection occurs through the '''respiratory tract''' and the mixing of birds at shows and sales and stocking pet shops with birds from multiple sources perpetuates infections.

Infection occurs through the '''respiratory tract''' and the mixing of birds at shows and sales and stocking pet shops with birds from multiple sources perpetuates infections.

Live nestlings are stunted, have a distended abdomen and '''feather dystrophy'''.

Live nestlings are stunted, have a distended abdomen and '''feather dystrophy'''.

Some nestlings survive with only feather dystrophy: grossly, primary wing feathers and tail feathers are either absent entirely or have thick sheaths and there may be '''haemorrhage in their shafts'''.

Some nestlings survive with only feather dystrophy: grossly, primary wing [[Fearthers - Anatomy & Physiology|feathers]] and tail feathers are either absent entirely or have thick sheaths and there may be '''haemorrhage in their shafts'''.

These birds are sometimes also infected with '''Psittacine Beak and Feather Disease Virus'''.

These birds are sometimes also infected with '''Psittacine Beak and Feather Disease Virus'''.

==Diagnosis==

==Diagnosis==

Histologically, finding the characteristic lesions and '''inclusion bodies''' is diagnostic: within the growing feather there is often massive infection of the cells in the zone of differentiation with inclusion bodies in nearly every cell. Inclusions in the epidermis of the skin can also be present.

Histologically, finding the characteristic lesions and '''inclusion bodies''' is diagnostic. Within the growing feather there is often massive infection of the cells in the zone of differentiation with inclusion bodies in nearly every cell. Inclusions in the epidermis of the skin can also be present.

'''Swabbing''' affected organs and submitting the swab for DNA probe testing is definitive, and, in cases with poorly developed lesions, may be the only way of making a positive diagnosis.

'''Swabbing''' affected organs and submitting the swab for DNA probe testing is definitive, and, in cases with poorly developed lesions, may be the only way of making a positive diagnosis.

Thomas, D. (2007) '''Infectious diseases of wild birds''' ''John Wiley and Sons''

Thomas, D. (2007) '''Infectious diseases of wild birds''' ''John Wiley and Sons''

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[[Category:Avian Viruses]]

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