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Last Updated: Wednesday, 1 March 2006, 15:06 GMT
Bird flu: Are pet cats at risk?
By Henri Astier
BBC News

Cat (generic)
No need to lock up your cat
The discovery of a German cat who died of bird flu - the first mammal found with the H5N1 virus in Central Europe - raises stark questions for pet owners across the world.

How easily can avian flu jump from birds to domestic animals? If a pet gets sick, should the owners be worried about their own health?

Scientists have known for at least two years that felines could catch the deadly bird flu virus.

It was found in 2004 in Thailand in two domestic cats. Big cats who had been fed infected chicken carcasses in a Thai zoo were also killed by H5N1.

And last year, wild civet cats died after contracting the virus.

Cats tend to go for sick birds, so it is not unexpected if cats catch and kill infected birds
Dr Paul Hunter
University of East Anglia
So the discovery of the dead German cat in an area where dozens of birds had died from H5N1 does not come as a big surprise.

Paul Hunter, professor of health protection at the University of East Anglia in the UK, points out that like all predators, felines hunt weaker animals.

"Cats tend to go for sick birds, so it is not unexpected if cats catch and kill infected birds," he told the BBC news website.

No alarm

The risk of cats getting the H5N1 virus is real. But according Dr Hunter, it is "not huge".

He notes that in affected areas in Asia, where people live in close proximity with poultry, hundreds of thousands of humans have handled infected birds - and yet less than 200 are known to have contracted the virus.


The H5N1 strain does not jump easily to other species - and this applies to cats as well.

However, Professor Peter Openshaw, head of respiratory infections at London's Imperial College, believes the German discovery represents a worrying development.

He says intimate contact between cats and their owners heightens the risk of transfer and potentially lethal mutation.

"It would be a risk because of the very intimate contact that people have with their cats," he said.

Professor Openshaw fears the development also increases the risk of the virus strain mutating into one that passes more readily between humans - a scenario that scientists fear will create a devastating global pandemic.

"Generally, when a virus makes an excursion into a [new] species, it is under considerable evolutionary pressure to mutate... Typically this is followed by a period of rapid mutation and then stabilisation within new species.

"This certainly adds to the concern that it may transmit to humans."

But Dr Hunter argues that there is little cause for alarm on that count as well.

"The risk of your cat getting bird flu from a bird is small, the risk of your getting it from your cat is equally small. A small risk within a small risk is a very small risk," he says.

Duck and chicken in France
Poultry could provide the best vehicle for the virus
But the issue - both for pets and humans - is whether the H5N1 virus mutates within the host population.

According to a 2004 paper by Dutch virologist Thijs Kuiken, cat-to-cat transmission is possible and could provide an "opportunity for this avian flu to adapt to mammals".

But for the time being experts are telling people not to panic.

"The thought to hang on to at the moment is the current strains of the virus appear to be really inefficient at infecting non-bird species," says the head of the British Veterinary Association, Frieda Scott-Park.

"And indeed the virus has been circulating throughout large swathes of the world already, and there haven't been numerous deaths from the disease in domestic mammals."

'Vaccinate cats'

Nevertheless, Professor Openshaw believes there is now a case for keeping cats indoors in risk areas.

Vaccination of animals that bring us into close contact with it seems to be a high priority
Professor Peter Openshaw
Imperial College, London

"It also raises the question of whether cats should be vaccinated... Vaccination of animals that bring us into close contact with it seems to be a high priority."

He urged a new focus on vaccines that are broadly protective rather than too specific, to improve chances of general protection.

But he admitted there was little incentive for pharmaceutical firms because such research had a high risk of failure with the prospect of low financial returns.

"In a situation where it is becoming endemic, vaccination seems a way forward. Relying on anti-virals is not realistic."

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