Lubica Necasova talks about a very common disease in parrots – PDD. PART II

Diseases

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Read also the first part of this interview:

Interview with the czech vet Lubica Necasova who is focused on avian medicine: Introduction. PART I

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What is your opinion about vaccination of birds? We’ve just published the book from Tony Silva who says that in USA there are many people who use it. However, when we try to find out something more about this in Europe there is just some experience about vaccination of Neophema species in Netherlands. So is there any chance to get a vaccine for parrots in the Czech Republic?

In our country there are licensed vaccines only for poultry and pigeons. As for parrots, in Europe we can find vaccines against polyomavirus and pox. Some breeders have used pigeon vaccines for parrots. Today, we know that it’s useless as it doesn’t work for other birds. Breeders thought that if they use a pigeon vaccine against paramixovirus (which was thought to cause PDD) parrots will be saved then. In my opinion, this can’t be true because there are many kinds of paramixovirus and every causes sligthly different disease. So such vaccination can make the imunne system stronger. However, any specific antibodies are not created. What is more, after a few years it has been found out that PDD is caused by bornavirus, not paramixovirus. Today, we are almost sure that it is bornavirus but there has to be also something else. One study shows that 30% of all parrots kept in captivity have antibodies against PDD and have this virus. However, they are not sick and often they will never be. So not all of parrots positively tested on PDD suffer of this disease but it seems that all sick birds have positive tests on bornavirus.

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The African Grey Parrot. (c) Joel Zimmer. This file is licensed under the Creative Commons Attribution-Share Alike 2.0 Generic license.

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Some breeders say that PDD never affects lories or lovebirds.

I don’t know. I think it’s maybe because nobody studies this. The only sure evidence is histological examination of proventriculus within the autopsy. In the Czech Republic there is not any avian pathologist. When you send the dead bird to any non-specialized pathologist then the result of autopsy is subjective. For me, reliable is only analysis comming from specialized avian pathologist. Price for such autopsy is about 1800 Kc (=65 euro). The problem is that not every owner of a lovebird will pay this, especially when the bird is dead already. I even found out PDD in a quail. This is not any species specific disease. We can find it not only in macaws but in amazon parrots, cockatiels, grey parrots, … We know about PDD for a very long time but there are still many things about this disease we don’t know yet.

Is there any chance to find a medicine against this disease?

It’s caused by virus so it won’t be easy. It’s the same as with PBFD, ebola or rabies which are difficult to cure. However, against PBFD some american researchers already evolved some vaccine so I’m curious about it. It’s not available on the market yet or licensed so it’s probably tested now.

You said that about 30% of all parrots in captivity have bornavirus. The birds which aren’t sick but have positive tests on PDD can transmit this disease as well?

Yes, they can.

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How sure can we be about the tests on PDD?

We can test PDD but the methods are very specific and sensitive. So if we want to be sure that it’s necessary to test it twice by different ways. The first method is PCR and the second is the test of antibodies. If both tests have positive results then we can say that our bird is infected by bornavirus.

Blood or feather sample is necessary?

Some lab wants blood, another can ask for a feather because they believe that PDD affects neural connection to the feather. In Germany they want a blood sample, in Great Britain they require a feather and blood.

So in the Czech Republic there is no lab which provides such examination?

Yes, there is. However, I guess it’s not very qualified one. When I saw their banner, they offer only PCR. But this is not a complete diagnostic. It’s the same as with PBFD. There is a huge chance of false negative or positive results. Without the test of antibodies you can’t test PDD. When I called them they were surprised about this and didn’t know anything.

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Macaws is the most affected group of parrots by PDD. (c) Eric Kilby. This file is licensed under the Creative Commons Attribution-Share Alike 2.0 Generic license.

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So today, there is no chance to cure a bird with PDD symptoms?

Probably not but it’s very arguable. As I said before, you can test this disease reliably only within the autopsy when the bird is already dead. There are birds with symptoms of PDD which we can save for a few years with proper diet and environment. Then, when the bird is dead, we have to do the autopsy. If not, nobody can be sure that the individual died because of the PDD. And breeders often don’t want to pay such autopsy. So vets would have to have some funds for this. Then we could create a database and get results with some statistical value.

So when I buy a bird I should test it on bornavirus definitely.

You are right. Many breeders in western Europe do complete tests when acquiring a new bird.

And young birds inherit this disease from their parents?

They might but it’s not a rule.

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READ THE SECOND PART OF THIS INTERVIEW ON THE NEXT TUESDAY!

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Title photo: (c) Lubomir Tomiska

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