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Last Updated: Tuesday, 6 February 2007, 13:21 GMT
Bird flu experts' answers
Virus expert Professor John Oxford and the Health Protection Agency's Jonathan Van Tam answer your questions about the bird flu outbreak in Suffolk.

HOW DID THE TURKEYS CATCH THIS VIRUS?
Ann Mudd, Salisbury

Professor John Oxford, virologist, London Queen Mary's School of Medicine and Dentistry: It has most likely come from another infected bird.

We know that H5N1 is transmitted silently by migrating birds. The warm weather will have affected their migration patterns. So the chances are that is how it has reached Suffolk.

Jonathan Van Tam, consultant epidemiologist, Pandemic Flu Office of the Health Protection Agency: It is unclear at this point how the turkeys became infected with the H5N1 virus.

This is the subject of thorough investigation by Defra (Department for Environment Food and Rural Affairs). The route of infection for the turkeys is important since clues from this may assist in preventing other incidents either in the UK or abroad.

IF ONE OF OUR CATS CAPTURES AN INFECTED BIRD, WILL H5N1 TRANSFER TO THE CAT? AND WILL THERE BE A SUBSEQUENT RISK TO HUMANS?
Graham L, Chesterfield

Professor Oxford: This has already happened in South East Asia, so the answer must be yes.

But the virus is extremely rare in Britain, so the chances are tiny. I don't believe anyone living outside the containment zone need worry about their cats.

If you're living less than a mile from the outbreak, you should be a bit more careful and maybe leave your cat outdoors, in case it has already eaten a bird. Those living further away, if they are still worried, should consider keeping their cat inside until all this dies down.

Jonathan Van Tam: It is unlikely that a cat will capture a bird infected with H5N1.

Should your cat bring home a dead bird remember that all dead wild animals may harbour infections and should be treated with care. If possible don't touch the dead bird directly (for instance use a handheld dustbin brush and pan), place the dead bird in a plastic bag and then seal it for example by tying in a knot or by using sticky tape to ensure it is air tight before placing it in the ordinary refuse.

Wash the dustbin brush and pan in hot water and detergent to remove any contamination to render it clean for use again. If any exposed skin (for instance your hands) comes into contact with the dead animal then wash the exposed area (for instance your hands) with soap and hot water and dry your hands. Even if your hands have not come into contact with the dead animal, it would still be advisable to thoroughly wash your hands with hot water and soap.

Domestic cats have been infected with H5N1 under experimental conditions and captive big cats (tigers) have been inadvertently infected in south east Asia through being fed chickens infected with H5N1. However non cat-human transmission of H5N1 has never been described.

IF THE BIRDS ARE KEPT INDOORS, HOW DID THEY GET BIRD FLU? HOW CAN THE COMPANY ASSURE SAFETY?
Andrea, London

Professor Oxford: It's unlikely that a building could ever be 100% secure. A very small bird could have made it through the ventilation system, for instance.

But the standard of biosecurity must be very high on this site because the infection has been confined to one shed.

Jonathan Van Tam: The normal biosecurity procedures in this type of farm with housed birds should prevent ingress of wild birds into the sheds.

It is unclear at this point how the turkeys became infected with the H5N1 virus. This is the subject of thorough investigation by Defra. The route of infection for the affected turkeys is important since clues from this may assist in preventing other incidents either in the UK or abroad.

WHY, IF THE BIRDS ARE IN AN ENCLOSED SHED, DO THEY NEED TO BE CULLED? WHY NOT LET THEM DIE? THIS COULD MEAN SOME BIRDS SURVIVING, MEANING THEY ARE IMMUNE TO THE VIRUS.
Ian Williams, Norwich

Professor Oxford: The problem with that is that it wouldn't work in practice. You can guarantee that 100% of the turkeys would die, and they would all die a horrible death.

Jonathan Van Tam: Unfortunately the virus causing this infection is highly pathogenic to poultry - that is to say that it kills almost all of the turkeys that it infects.

Defra made the decision to humanely cull, under controlled conditions, all of the birds to reduce the public health threat from the affected birds. This decision was taken in the best interests of the general public and the poultry.

DO YOU THINK THAT KEEPING BIRDS IN UNNATURAL SURROUNDINGS LOWERS THEIR IMMUNE SYSTEMS?
Sarah Patrick, Reading, UK

Professor Oxford: I suspect it does. I'm not criticising these places but the birds won't be at their prime to resist diseases.

Jonathan Van Tam: No. Poultry are prone to catch this type of virus and there is no conclusive evidence to suggest that these birds were more susceptible to disease.

I'M LOOKING FOR ONE SINGLE ARTICLE OR MENTION ON THE BBC WEBSITE ABOUT HOW HUMANE THE METHOD OF KILLING THESE TURKEYS IS, BUT CANNOT FIND ANY. SOME OF US CARE ABOUT THIS AS WELL AS THE EFFECT ON HUMANS.
Kitto, Geneva

Professor Oxford: It's very difficult to kill 100,000 turkeys, not least because you run the risk of getting infected yourself.

But people can be reassured that the birds will be treated much more humanely than those which were shown getting slaughtered by being thrown on fires in South East Asia. They will have to cull the turkeys as painlessly as possible.

Jonathan Van Tam: The disposal of the culled birds is being carried out under controlled humane conditions overseen by Defra.

WHICH WILD BIRDS ARE MOST LIKELY TO BE CARRYING THE VIRUS?
April Showers

Professor Oxford: Wild migrating birds like geese, ducks and swans.

Jonathan Van Tam: Wild aquatic migratory birds are the most likely birds to carry avian influenza viruses.

They may have little or no symptoms but excrete virus in their faecal material and hence into watercourses. Other birds can then become infected through drinking this water (there is no evidence of humans being infected in this way) or through spreading this faecal material to contaminate the feed that they consume.

I HEARD COOKING KILLS THE VIRUS, WHAT ABOUT PRE-COOKED MEAT?
Anon

Professor Oxford: Pre-cooked meat will have been heated and that will have destroyed the virus. It is actually very fragile and easy to kill.

Jonathan Van Tam: As cooking kills the H5N1 virus all precooked meats would be free of risk of infection.

GIVEN THE WARNING THAT THIS PARTICULAR STRAIN OF BIRD FLU IS HIGHLY PATHOGENIC, WHY WOULD DISEASED BIRDS BE MOVED TO STAFFORDSHIRE?
Sheila Branch, Ely

Professor Oxford: This has been a difficult series of decisions for Defra. The carcasses will have to be moved in steel containers which are totally secure.

I suspect this option was the best compromise. They will have thought about it very carefully.

Jonathan Van Tam: All of the transport is being leak tested to ensure the safety of the public during the transport of the dead birds.

WHY IS IT THAT WHEN A LARGE COMMERCIAL ENTERPRISE GETS HIT WITH THIS IT POSES LITTLE DANGER TO HUMANS, YET WHEN THE SCARE-MONGERING OVER BIRD FLU WAS AT ITS HEIGHT A YEAR AGO IT SEEMED A SINGLE INFECTED BIRD WAS ENOUGH TO WIPE OUT HALF THE POPULACE?
D. McNicholl, Tain

Professor Oxford: The dead swan in Fife was in a public place - anyone could have walked up to it. But the most recent case involved a secure site which only affects the people who work there.

I don't believe last year's incident was overstated. It was a huge educational exercise: people know now that a dead swan is potentially dangerous.

Jonathan Van Tam: In either scenario, there would be a very small theoretical risk to human health.

As time passes and more knowledge is gained, scientists are better able to understand and manage these risks on a case-by-case basis. The practices being undertaken are designed to minimise the risk to the population and ensure that the population is safeguarded.



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