Budgerigar fledgling disease bfd birds online

Budgerigar Fledgling Disease (BFD)
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Budgerigar fledgling disease bfd birds online

16 day old Bourke's parakeet suffering from BFD.

The English name Budgerigar Fledgling Disease, BFD for short, means "budgerigar nestling disease" in German. On the basis of the name it can already be deduced that young birds are affected by this serious disease. But contrary to the name, it is not only budgies that suffer from BFD, but also other parakeet species.

BFD is caused by polyomaviruses and some experts believe that the disease may be a severe form of the same infection that causes French Wall in a mild form. However, this knowledge is not yet completely secure, which is why there are also opposing views among the experts.

How serious the effects of an infestation with BFD are, about this informs this chapter of Birds Online. For many years, bird lover Andrea Szabo has kept various species of parakeets and other birds. She has also had her birds raise offspring in the past. Some time ago a strange disease appeared in your bird population, to which young birds fell victim again and again. In the meantime Andrea Szabo knows that it is BFD. To share her knowledge, she wrote a field report about this treacherous disease in early 2013, which contains a lot of important information.

Field report and pictures by Andrea Szabo (Budgie Bytes), February 2013

How it all began

Budgerigar fledgling disease bfd birds online

14 day old bourke parakeet suffering from BFD.

In 2006 I started with the sporadic breeding of Neophemas. Since then, sporadic young birds have stunted after hatching and eventually died. However, only years later I realized that it was always the same phenomenon. In retrospect, I benefited from the many photos I had taken during the broods.

Because there were more and more cases of stunted young birds, I gave up the breeding in summer 2012. But it was to take several more months before I came to a conclusion as to the cause of these deaths. Because the underlying viral disease has not yet received much attention in German-speaking countries, or it is often equated with French molt, since the pathogens in both cases belong to the polyoma group.

My experience taught me that the symptoms of the two diseases, however, differ significantly. The French molt shows up only at an age when the chicks suffering from BFD have usually long since passed from life. It can be said that the plumage problems in French Molt usually start at the age of three weeks, when the chicks are already wearing most of their feathers, whereas the young birds affected by BFD often do not get older than one to two weeks. Up to this point, due to the delayed development, they usually do not develop any plumage worth mentioning.

Furthermore, I was unfortunately on the wrong track regarding the cause for a relatively long time. The reason for this was that on the one hand an examination of a deceased young bird showed a negative result with regard to polyoma. On the other hand, due to a hint of an avian expert, I was of the opinion that an infestation of my bird population with bacteria, exactly E. coli, would be the cause of the deaths among the young birds. Since at first no more suitable explanation offered itself, I investigated for a long time unsuccessfully further. However, no breeder, no veterinarian and no veterinary clinic could explain to me a connection between these bacteria and the symptoms that appeared in my bird population. I could really exclude E. coli as cause nevertheless not, because a moderate infestation with this pathogen was proven in my animals.

The following progression occurred in the broods in my bird flock:

Year healthy chicks stunted chicks unexplained death deaf eggs
2005 0 0 1 2 2006 4 1 1 2 2007 0 1 0 3 2008 1 0 0 6 2009 1 1 0 2 2010 2 3 0 7 2011 13 1 2 11 2012 0 1 0 44 Total 21 8 4 77

BFD and the risk of confusion with other disorders

Budgerigar fledgling disease bfd birds online

Two Bourke's parakeets of the same age, one of them suffering from BFD: Both birds are 23 days old. It can be clearly seen that the right bird is strongly retarded in its growth.

The disease was first described in budgerigars, from which the name Budgerigar Flegdling Disease (BFD) is derived. Literally translated into German, this term means "budgie-nestling-disease. It can also be found under the alternative names of nestling disease, young bird disease, nestling mortality in budgies, or other similar names in the literature. The trigger of this disease is a virus from the polyoma family.

BFD should not be confused with "Polyoma". In common usage this usually means the French moult (hop disease, racer disease). Also, BFD should not be confused with PBFD (Psittacine Beak and Feather Disease), a serious disease with a rather similar acronym. In fact, although French molt is also caused by a virus from the polyoma group. But it is probably a different polyomavirus species from BFD. The illness PBFD is again released by a Circovirus.

In some places Papova is also mentioned as a cause for BFD. However, this is no longer correct today, as the formerly used generic term papoma for viruses of the families polyoma, papilloma and SV40 has been replaced in the meantime. That is, it is no longer valid in the nowadays official taxonomy.

Symptoms of BFD

Budgerigar fledgling disease bfd birds online

13 day old Bourke's parakeet with BFD and a very red belly.

Occasionally there were chicks in my flock whose growth ended at a certain age. Presumably, however, they suffered from retarded growth right from the beginning. In total eight birds were affected, in addition there were four further unexplained deaths within eight years. Observable were splay legs, rachitic looking legs, stunted toes, stunted wings, in some birds an asymmetry of the body as well as a red, swollen looking lower abdomen. In some individuals the eyes did not open or, if the chick lived long enough, did not open until many days after the date when this should normally occur. Some of my chicks had constricted eyelids. Some of the juveniles were unable to stand or sit.

Mostly the death occurred between the tenth and 16th day of life. In one case the chicks were born on the first day of life, in two cases only at the age of 24 days. Only one chick affected by the severely retarded growth survived. My adult birds do not show any symptoms, this is true for Bourke's parakeets as well as for parakeets. My ornamental parakeets have been spared from the disease so far.

I had the last chick, which appeared stunted, dissected after its death. Unfortunately, the findings were rather sparse. From the report of VetMed Vienna it was clear, that in the young female Schonsittich there were unclear unspecific liver necroses (necrosis = dead tie). No concrete cause for the death of the chick could be found.

Finally first findings

Budgerigar fledgling disease bfd birds online

21 day old parakeet suffering from BFD.

I put a lot of effort into a lengthy research. By chance I found this in a budgie forum. In that forum someone described exactly the symptoms which had appeared in my bird population. I followed this trace further and I got in contact with Gerd Bleicher, a very renowned German budgie breeder. He explained to me that it is BFD and that this viral disease is hardly a subject of discussion in German-speaking countries around dead chicks. However, there are some publications from England and Canada.

By means of some English-language scientific publications I could determine finally a correspondence with my case. This was true for the symptoms of the affected birds as well as for their age at death and the occurrence of the symptoms. Furthermore, my experience and the statements of the publications coincided with regard to the fact that a bacteriological and virological examination of dead young birds does not provide evidence of BFD. This explains why in the examination report I commissioned the result was negative. According to the literature, the first isolation of the virus in a budgie embryo was successful.

The following two English language publications were particularly helpful to me:

Therapy of the BFD

After intensive research it is clear to me that there is currently no treatment against this disease. If a flock is affected, it is advisable to pause breeding; in addition, thorough disinfection with iodine-containing cleaning agents or bleaching agents is advisable.

According to the literature, attempts were made to separate the affected parakeets by sex and remove them from the flock for seven or eight months. In some cases this was successful, but in other cases these measures did not help. For me, this would not be an option anyway, as I do not have the space to house the birds separately.

As soon as I have new findings, I will be happy to share them with you.

For 2013 I am not planning any broods for the time being – and it reares me a little that at least for my adult birds there is no danger from the virus.


I would like to thank Gerd Bleicher in particular. He has been able to help me considerably. He advised me extensively despite his busy schedule.

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