′No proof′ of bird flu human-to-human contagion | Science| In-depth reporting on science and technology | DW | 08.04.2013
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'No proof' of bird flu human-to-human contagion

The World Health Organization has stressed there is no evidence so far of human-to-human transmission of the H7N9 bird flu virus in China - although several members of one family have fallen ill in Shanghai.

China announced just over a week ago that it had been found in human for the first time - with six deaths and 21 confirmed cases so far. In the past, China, which has been criticised for reactlying slowly to such public health threats, has been praised in this case.

Gregory Härtl is with the Director-General's office at the World Health Organization (WHO) - and the organization's former spokesperson for avian influenza and other epidemic diseases.

DW: I suppose the most important thing to stress - that you've been stressing - is that so far there is no evidence of human to human transmission.

Gregory Härtl: Exactly, for the moment there's no evidence of human-to-human transmission. We have 21 confirmed cases. We're following up over 600 contacts, but for the moment there's no evidence of human-to-human transmission.

And what can you tell us about the H7N9 bird flu virus?

As you say it's a virus which originally was in birds but it has mutated into a form which really no longer is a bird virus because it now has a mammalian receptor on it which allows it to infect mammals, i.e. humans. So we are  now for the first time ever seeing human infections with this virus.

The World Health Organization's Gregory Härtl

The World Health Organization's Gregory Härtl

So it is able to infect humans. It is ita matter of time until we see a human to human transmission? What are the factors that could influence that - based on past experience?

It is impossible to say if this is a virus which will ever become a virus which can infect humans from human to human. If you look at what's happened with H5N1 - another bird flu virus, the bird flu virus which everyone talks about. It first emerged in 1997, completely disappeared for six years, re-emerged in 2003 and for the last ten years has not mutated into any form which is transmissible between humans.

But what we're seeing here is a new form of bird flu, right? We're talking here about the mutations of bird flu.

All viruses originate in birds. So every single flu that you and I and your brother have had have been bird flu in the beginning. So what happened is that influenza viruses mutate constantly and they mutate eventually into forms that can spread between humans and that's how you and I get flu. But not all influenza viruses do. There are hundreds if not thousands of influenza viruses out there and only a very small minority of those viruses ever become transmissible between humans.

You mentioned the 2003 outbreak in Asia - there has been some focus on china's ability to report this new outbreak and to respond to it. What is your feeling - what is the feeling from the WHO regarding China's response to this case?

First of all, we're not talking about Bird flu in 2003 - we're talking about SARS...

Yes, but the reason I refer to that is that we're talking about responses to massive public outbreaks to health threats - that's the link I'm making...

Okay, China has now been exemplary, the cooperation between the Ministry of Health and the WHO has been very strong - it's been consistent, it's been open, it's been transparent. We have hourly telephone conferences with them; we meet with them every day. They give information proactively, they meet the press. I think they are doing everything they possibly can and they could do in order to combat this outbreak.

What can you tell us about the region within China as to where this virus is currently to be found and perhaps spreading?

At the moment, all the cases that we've seen are all near the eastern coast of China from Shanghai up towards the north and slightly inland. We don't know why the cases are only there, but that's what we've seen so far.

Gregory Härtl is with the Director-General's office at the World Health Organization (WHO) in Geneva.