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Bird Flu for beginners
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tahir



Joined: 28 Oct 2004
Posts: 44533
Location: Essex
PostPosted: Tue Sep 20, 05 1:15 pm    Post subject: Bird Flu for beginners  Reply with quote    

Instant Expert: Bird Flu


The H5N1 strain of influenza - often referred to as bird flu - was first known to have jumped from chickens to humans in 1997. Since 2004 it has ripped through Asian poultry farms, and had a 70% mortality rate in the first 70 people it is known to have infected. Health authorities fear this strain, or its descendents, could cause a lethal new flu pandemic with the potential to kill billions.

Flu has been a regular scourge of humanity for thousands of years. The flu viruses are a large family, each possessing a mere 10 genes encoded in RNA. All of the 16 known groups originate in water birds, especially ducks and gulls. The virus is well adapted to their immune systems, and does not usually make them very sick. This leaves the animals free to move around and spread the virus - just what it needs to persist.
Rampaging virus

But every now and then a bird flu virus jumps to an animal whose immune system it is not adapted to. In chickens, a forest bird originally and not a natural host, it causes a moderate disease but can readily mutate to a more severe strain. Just such a strain of H5N1 flu, named after its surface proteins, has been rampaging through large chicken farms in east Asia.

That is of concern because, in 1997, scientists found for the first time that H5 flu is capable of infecting humans. It was found in 18 people, six of whom died. All the poultry in Hong Kong were destroyed to stop the threat. But it continued to circulate, especially in China.

There were further human cases in China in 2003. Then in early 2004 Vietnam reported widespread poultry outbreaks and some human cases. After initial denials, Cambodia and Thailand admitted they had outbreaks too, followed by China. That was immediately after China had denied a New Scientist report that scientists strongly suspected Chinese outbreaks.

A mass poultry cull stopped the outbreaks by March 2004, by which time 23 people had died. But the virus persisted, most probably in ducks. Attempts to blame its persistence and spread in the region on wild birds are widely discounted by scientists. The outbreaks started again in summer 2004, and by mid-April 2005 had caused a total of 51 human deaths, all in Thailand and Vietnam.
Making the jump

The two or three flu virus families that have made the jump to humans mostly cause mild disease, because they have adapted to our immune systems. A yearly winter flu epidemic afflicts most of the world. But it is not totally benign. About 700,000 people around the world die of it each year, mainly the very old, very young and the infirm.

Common flu vaccines are increasing in popularity, although flu evolves so fast that we need new shots every year. In 2004 an unexpected shortage of vaccine in the US underscored the fragility of the vaccine supply, which is produced by very few manufacturers. As New Scientist predicted, it took strenuous efforts to limit available supplies to those most at risk of serious illness, preventing excess deaths.

But flu is at its most deadly when it first makes the jump to people, having had no opportunity to adapt itself to our immune systems. H5N1 has continued to infect humans as the outbreak in poultry has raged, with an apparently high fatality rate. It has so far has been hard to contract, and has not spread readily between people. If this viral strain should acquire that ability, it could become a lethal pandemic - the name for an epidemic that spreads worldwide.
Deadly pandemic

That is what happened in 1918, when a virulent flu strain appeared in humans and killed 50 million people within a few months.

There have also been two less catastrophic pandemics. The so-called "Asian" flu of 1957 caused between one and four million deaths, while 1968's "Hong Kong" flu - with about half the estimated deadliness of the Asian flu - caused one to two million deaths. Both of these were human flu viruses which had recombined with bird flu viruses, rendering them unrecognisable to the human immune system. The 1957 strain was nearly released by accident in 2005.

Virologists generally agree that we are due for another pandemic. So they are very worried about H5N1, because - like the 1918 event - it seems to be evolving to become more deadly to mammals. This is largely in China and, possibly, as New Scientist revealed, in vaccinated chickens.

It could evolve into a potential pandemic that way, or by recombining with human flu, especially as most people in the Far East are not vaccinated against ordinary flu strains.
Mitigation measures

Fortunately we can make vaccines for the H5N1 strain, although our ability to get them tested and manufactured in time for a pandemic is in doubt. Once an effective vaccine is produced, yet another hurdle would be administering it swiftly. If either aspect of that process should fail, the only backup would be antiviral drugs. A few new ones are on the horizon, but existing drugs are in short supply.

If the flu virus changes genetically, it may become less deadly. However, there is no reason to think this will happen, and a highly contagious virus with a 70% death rate is a terrifying prospect, particularly given the speed of modern international travel. There is also a chance that it could evolve into a completely new disease, which we could fail to spot before it spreads.

Even if H5 does not trigger the next pandemic, its cousins H7 and H9 could. H7 is present in the same region and also infected large numbers of Dutch people in an outbreak in 2003. Although it caused few symptoms, and only one death, fears remain that such a poultry virus could cross-breed with a human flu, making it even more dangerous.

Some scientists are not willing to wait and see. They are trying to breed contagiousness into H5N1 to see if it is likely to happen. Others are breeding replicas of the 1918 virus - from samples recovered from victims - to see just what made it so deadly. But some feel that those experiments, because of the potential for escape from the lab, put us at as much risk as the natural evolution of the virus.

Debora Mackenzie, 6 May 2005

http://www.newscientist.com/channel/health/bird-flu

tahir



Joined: 28 Oct 2004
Posts: 44533
Location: Essex
PostPosted: Tue Sep 20, 05 1:18 pm    Post subject: Reply with quote    

Bird flu knocks on Europe’s door

* 18:03 25 August 2005
* NewScientist.com news service
* Debora MacKenzie

Chief veterinary officials from the European Union’s 25 member states met in Brussels on Thursday to discuss what to do if wild birds carrying H5N1 bird flu bring it to Europe from Russia. But they concluded it is not clear whether wild birds are spreading the virus in Russia, nor how likely it is that birds migrating into Europe could be carrying it.

H5N1 bird flu has been identified in backyard poultry in the Novosibirsk region of Russia, where an outbreak started in late July. DNA sequence information from samples near Novosibirsk shows it is highly similar to the virus that killed thousands of wild birds at Qinghai Lake in China in May 2005.

Russia has also reported outbreaks involving H5 bird flu in backyard poultry in its Altai Kray, Tyuman, Omsk, Kurgan and Cheyabinsk regions, which cover a band of territory parallel to the northern border of Kazakhstan. H5N1 flu has also been confirmed in Kazakhstan. It is not clear how similar any of these latter viruses are to the Qinghai H5N1 or others that have circulated in east Asia and caused 57 human deaths so far.

But whether this spread is likely to continue into Europe depends on whether it is being carried by healthy migrating birds. If instead the virus is being spread by trade in infected poultry, as it has been in south-east Asia, the picture would be different. And the infections reported so far do coincide geographically with major rail, trade and travel links through the region.
Reservoir risks?

Evidence for spread by wild birds is circumstantial. Yevgeny Nepoklonov, head of the veterinary department of the Russian Agriculture Ministry, told the World Animal Health Organisation (OIE) in Paris this month that in the six territories where outbreaks have been reported, “the first [domestic] birds to be affected are those kept in homes close to reservoirs” – where wild birds may visit.

On the other hand, not one healthy wild bird carrying highly pathogenic H5N1 has yet been reported, apart from a few carrying a somewhat different virus in Hong Kong in 2002. Hon Ip, a virologist at the US National Wildlife Health Center in Madison, Wisconsin, US, notes that in Russia’s report on Novosibirsk to the OIE, the H5N1 virus it had isolated from a wild duck was different from the viruses isolated in its domestic poultry.

“No data that shows the wild birds were the vector of transmission has been made available at the present time,” Ip commented on ProMED-Mail, an internet bulletin board on emerging disease. “The same pattern of spread can just as easily be seen as from the major routes of human transportation.”
Holding fire

Adding to uncertainties, an investigation of an outbreak of bird flu on remote lakes in Mongolia by the Wildlife Conservation Society in August found that only 100 birds of more than 6000 on the lake died, suggesting either that the virus does not infect many birds in wild flocks, or the majority of birds that caught the virus remained healthy carriers.

If wild birds are carrying H5N1, say European veterinary experts, the key to preventing outbreaks will be to prevent contact between poultry and wild birds. Free-range chickens have already been moved under cover in the Netherlands, which has had major outbreaks of other kinds of bird flu recently.

But the vets in Brussels recommended that EU countries: hold their fire, increase their monitoring of flu viruses in wild birds, be ready to destroy infected birds, bring free-range animals inside if the virus is detected. They recommended that in at-risk situations poultry vaccination might be considered as a risk-mitigating measure.

Bird Flu - Learn more about the flu pandemic that could kill millions in our continually updated special report.

cab



Joined: 01 Nov 2004
Posts: 32429

PostPosted: Tue Sep 20, 05 1:26 pm    Post subject: Reply with quote    

Not a bad summary, thanks!

The only thing I'd add is that this is an amazingly dynamic situation. Reports and updates on infections, test results and precationary measures are now coming out daily, have been for some time.

Sometimes it looks like we're just waiting for the spread of a diseasel the truth is that health workers and microbiologists are waging a constant battle against it.

Alchemist



Joined: 02 Mar 2005
Posts: 123
Location: Aberdeenshire
PostPosted: Tue Sep 20, 05 1:49 pm    Post subject: Reply with quote    

One of my colleagues asked me the other day if I was worried about bird flu after seeing on the news that the Dutch had ordered all their birds indoors. When asked if our chickens posed a threat to us I had to say I hadn't a clue. I imagine that the risk is exceedingly small even if the virus does spread further west, but thinking like that definitely makes you want to look into it more carefully even if only to be able to be certain it isn't an issue.

dpack



Joined: 02 Jul 2005
Posts: 37439
Location: yes
PostPosted: Wed Sep 21, 05 5:59 pm    Post subject: Reply with quote    

run to the hills with your best chucks when we are all dead ,return and claim the world.. dont panic......

thos



Joined: 08 Mar 2005
Posts: 1139
Location: Jauche, Duchy of Brabant (Bourgogne-ci) and Charolles, Duchy of Burgundy (Bourgogne-ça)
PostPosted: Thu Sep 22, 05 7:16 am    Post subject: Reply with quote    

I had decided that this was perhaps not the best time to start to keep chickens. However

If bird flue gets here, they should be safe if I keep them in the run.

If the human strain gets here, my family would be more likely to catch it from other people than my chickens.

Would the panel agree?

Nanny



Joined: 17 Feb 2005
Posts: 4520
Location: carms in wales
PostPosted: Thu Sep 22, 05 7:38 am    Post subject: bird flu Reply with quote    

almost looks that way

if it takes hold it'll get you one way or another but least of all through your own hens, it appears

vaccination of flocks seems the logical way forward if they can get enough vaccine together.

a lot of foods have the vaccines in them already so it would be just another additive i guess

trouble is the panic that will ensue and that will mean a demand for the destruction of back yard birds.

that will be a terrible time

i don't want to have to see things like those when foot and mouth was present here several years ago.

smaller scale but every bit as unpleasant

Alchemist



Joined: 02 Mar 2005
Posts: 123
Location: Aberdeenshire
PostPosted: Thu Sep 22, 05 7:39 am    Post subject: Reply with quote    

I reckon so. It's relatively easy to quarantine the chickens if need be. Much more difficult to avoid people with a cold.

cab



Joined: 01 Nov 2004
Posts: 32429

PostPosted: Thu Sep 22, 05 7:55 am    Post subject: Reply with quote    

thos wrote:
I had decided that this was perhaps not the best time to start to keep chickens. However

If bird flue gets here, they should be safe if I keep them in the run.


That rather depends on the run and the extent of air flow it has, and contact between wild bird faeces particles in the air... So they're safer, but not totally safe.

Fairly sell sealed off intensive farms in Japan have been hit by bird flu, remember.

Quote:

If the human strain gets here, my family would be more likely to catch it from other people than my chickens.

Would the panel agree?


If a sideshoot of this strain becomes transmissible from human to human, that's when it becomes the big killer we all fear. Personally, I wouldn't yet worry about transmission from your own livestock to you.

cab



Joined: 01 Nov 2004
Posts: 32429

PostPosted: Thu Sep 22, 05 7:56 am    Post subject: Re: bird flu Reply with quote    

Nanny wrote:
almost looks that way

if it takes hold it'll get you one way or another but least of all through your own hens, it appears

vaccination of flocks seems the logical way forward if they can get enough vaccine together.


For over half a century, microbiologists have been arguing that we need facilities to produce new vaccines in large bulk really, really fast. No one pays attention

Nanny



Joined: 17 Feb 2005
Posts: 4520
Location: carms in wales
PostPosted: Thu Sep 22, 05 10:11 am    Post subject: bird flu Reply with quote    

always seems like a closing of the barn door after the horse has bolted when it comes to those sorts of things

not being an expert so i will ask

had the govt pulled it 's finger out and started vaccinating stock would the tragedy of foot and mouth been avoided i.e. the mass destruction[/i]

cab



Joined: 01 Nov 2004
Posts: 32429

PostPosted: Thu Sep 22, 05 11:11 am    Post subject: Re: bird flu Reply with quote    

Nanny wrote:

had the govt pulled it 's finger out and started vaccinating stock would the tragedy of foot and mouth been avoided i.e. the mass destruction[/i]


No. Wouldn't have helped. But that's WAAAY off for this discussion.

Nanny



Joined: 17 Feb 2005
Posts: 4520
Location: carms in wales
PostPosted: Thu Sep 22, 05 11:33 am    Post subject: bird flu Reply with quote    

why?

i was thinking if vaccination would be suitable for chickens why wasn't it suitable for cloven 'oofs at that time

did it mutate too quickly for that or what

cab



Joined: 01 Nov 2004
Posts: 32429

PostPosted: Thu Sep 22, 05 12:38 pm    Post subject: Re: bird flu Reply with quote    

Nanny wrote:
why?

i was thinking if vaccination would be suitable for chickens why wasn't it suitable for cloven 'oofs at that time

did it mutate too quickly for that or what


Rather than deal with F&M here, we're better off doing it in another thread; I'm conscious that we could easily lose track of keeping this thread for simple, plain talking concepts of bird flu.

saffranne



Joined: 23 Aug 2005
Posts: 428

PostPosted: Thu Sep 22, 05 2:48 pm    Post subject: Reply with quote    

no point in worrying about something that might or might not happen
my hens all 120 of them plus chicks are part of my everyday life,extended family along with the 6 cats and three dogs,ooops sorry forgot to mention husband.

they are a very lively bunch and the eggs are a double bonus and very nice too

if we ever do get the bird flu,which i sincerely hope we dont,then we will no doubt deal with it

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