Polyomavirus infection of parrots
The Polyomavirusinfektion is a common in parrots occurring viral disease caused by the budgie polyomavirus from the family of Polyomaviridae is triggered. The disease occurs worldwide and especially in budgerigars - also referred to here as budgerigar nestling disease . However, numerous other parrot species such as lovebirds , macaws and the eclectic parrot are susceptible, with them the clinical symptoms are usually less pronounced. Clinically, there are either fatalities in nestlings (acute illness) or fletching disorders (chronic course). The diagnosis is made by detecting the virus in feces or blood. Treatment is only possible symptomatically, which is why stocks should above all be protected against the introduction of the virus. If a herd is affected, a rapid infection can at least protect against further deaths.
Route of infection
Infection occurs through faeces, skin and feather cells, and in the budgie directly to the offspring ( vertical ). The virus is stable in the environment. Adult animals in particular are often symptom-free shedders. Co-infections with circoviruses also occur.
Clinical picture
The acute course can be observed especially in nestlings. Affected animals are weak, no longer eat and sudden deaths are possible. Budgies can have a mortality rate of up to 100%. Yellow discoloration of the skin and bleeding under the skin may occur.
The chronic course occurs in those nestlings who are either protected by maternal antibodies or are older than two weeks when infected. In these animals, malfunctions in feather formation dominate with failure of the flight and control feathers . The regrowing feathers are usually twisted or misshapen and have persistent feather sheaths. As a result, the animals are unable to fly and are also referred to as "runners" or "hops", which is colloquially known as " French moulting ".
The clinically inapparent course is characterized by the absence of symptoms. The animals have high levels of antibodies, but keep shedding viruses. In the event of disorders of the immune system - such as due to stress, feeding errors, brood - these animals can also develop a manifest disease.
As a result of liver damage, the urine of all animals can turn yellow. Disorders of the goiter function such as regurgitation or central nervous symptoms can also occur.
Diagnosis
In acute and chronic courses, the symptoms give an indication of the disease. Only the direct detection of virus deoxyribonucleic acid by means of the polymerase chain reaction (PCR) from the blood or a cloacal swab sample is certain . Virus detection via a cell culture is also possible. The detection of antibodies with a neutralization test can also be carried out in budgerigars, but a negative result does not rule out a polyomavirus infection.
In the histopathological examination of deceased animals, inclusion bodies can be found in feather follicles, kidneys, liver and spleen.
Treatment and prevention
A specific therapy is not possible, at best side effects can be treated symptomatically. In addition, for example, sufficient climbing opportunities can be offered to compensate for the inability to fly. The fletching disorders may subside after a few moults .
If the disease occurs in a herd, no further breeding attempts should be made for three to four months. During this time, sufficient contact between the birds should be made possible in order to force a rapid infection and thus antibody formation. This means that in the future at least acute illnesses and thus deaths, but not chronic illnesses, can be prevented.
To protect them from being introduced into a herd, newly purchased birds should first be kept in quarantine and tested for polyomaviruses. In addition, budgies should not be kept together with other parrots, as the latter are often reservoirs of pathogens without showing signs of disease themselves.
literature
- Michael Pees: Key symptoms in parrots and parakeets . Enke, 2nd edition 2011, ISBN 978-3-8304-1084-3 , pp. 171-173.
