23 November 2012, 12:53

British birds affected by life-threatening virus

British birds affected by life-threatening virus
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Some British birds being threatened by a life-threatening virus - thought to have come from Scandinavia and Central Europe by mosquitos. The virus targets commonly seen garden birds including house sparrows, wood pigeons and members of the tit family who are particularly vulnerable. It's known as Avian Pox and causes large pink swellings. Dr Becki Lawson, a wildlife vet with the Zoological Society of London speaks on the issue.

In certain species of garden birds the disease has been established. We see individual birds sporadically affected. In great tits the disease has been seen again occasionally since 1970s in Scandinavia. In Central Europe there have been a lot of incidents around mid-2000, shortly before our first case, in countries such as Austria, Hungary and Czech Republic. In 2006-2007 we’ve received a handful of reports. In recent years we see an increased number of reports, sometimes with following appeals to the public that helps us track these diseases by keeping an eye on it. But we’ve seen a very rapid range extension with the disease spreading westward, into South-West England, Wales and now northward. So there’s rapid spread of the disease within the tit family in Britain.

What does this look like on birds themselves? How do you know when a tit or any other bird has got avian pox?

Well, in tit birds the lesions are really rather characteristic. They most commonly occur on the head, typically on the sides of the face, often obscuring eyes. People describe them as “swellings”. Sometimes birds loose feather, so they can be bright pink. In the initial cases they may be confused with “sticky berries”, stuck to the bird’s face. So they have that type of appearance. In other species the lesions are much smaller and photographs can be very helpful for us, because there’s potentially other explanation for skin conditions in some species of birds.

Does the virus itself kill the bird? Or is it the nature of this large swellings which stops them flying or stops them eating?

It could be either of those, but we think happens quite frequently is that these birds can cope with lesions of reasonable size, but if they are obscuring the vision, birds are more likely to fall prey to predators. They can also become a more serious bacterial infection.

Dr. Lawson, you’re a wild life vet. This sounds obviously worrying for individual birds. Is this another example of a virus seemingly taking hold on previously healthy population of species, where we didn’t see it before? With the bird population going down, the ash fungus affecting the trees, it looks like all kinds of things are affecting British wildlife.

Emerging infectious diseases are very important to monitor and to try to understand. We did spectacular example. We’ve worked in the three publications, the studies that have come out today. Two of them focus on the expert findings of scientists from Oxford. They have found a very severe impact on the individual. The prediction is that we won’t see a population level decline in great tits, due to this disease. So we’ll continue to monitor this situation and we’re appealing to the public to keep helping us by reporting.

If somebody finds a clearly ailing bird with these lesions, could somebody keep it, feed it, would it recover?

Unfortunately, there’s no specific medicine available for avian pox. In that situation I’d recommend that they speak to their local veterinary to get advice.

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