Bird Flu Strain May Be Transmissible Between Humans

Aug 7, 2013
Originally published on August 7, 2013 5:05 pm

new study in the British Medical Journal shows the first probable transmission between humans of a new strain of avian flu — the H7N9 virus.

A 32-year-old woman in China became sick and died after caring for her father who had the H7N9 virus. The father also died.

However, the authors of the study stress this does not mean the virus has evolved to be easily transmissible between humans.

Until now, people sickened by this particular strain of bird flu were in direct contact with poultry before contracting the virus. 


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A few years back, we were hearing about a possible pandemic from the new strain of avian flu called H5N1. The pandemic never happened because it never spread easily from human to human. Most of the infections came from direct contact with live poultry.

Well, now a study in the British Medical Journal is reporting on the first likely human-to-human transmission of a new strain of avian flu called H7N9. The study followed a case in eastern China where a father infected by contact with live poultry may have passed the virus on to his daughter. They both died earlier this year.

Dr. Peter Horby is an avian flu expert and senior clinical research fellow at Oxford University, and he joins us from Singapore. Welcome.

PETER HORBY: Thank you.

HOBSON: So this was the fear back in 2006, that there will be human-to-human transmission. Are we seeing the worst fear realized at this point?

HORBY: No, we're not. In 2003, we saw the H5N1 bird flu virus, and there was limited human-to-human transmission in that, and that never really progressed to become adapted to humans. With this new virus, H7N9, we've seen some limited human-to-human transmission.

HOBSON: Do we know for sure that this was human to human? The reports say that this daughter visited her father, looked after him as he was dying. But he had contact with poultry, she apparently did not. Are we sure that that's the case?

HORBY: In all likelihood it was because the woman had very intense exposure to her father while he was ill. And they interviewed the family and there was no other reported exposure to poultry, and she actually spent a lot of time just in the housing complex. So I think given that and also the fact that the viruses were almost identical, it's highly probable that this was person-to-person transmission.

HOBSON: Were you surprised this report of this daughter contracting the H7N9 from her father?

HORBY: No, I wasn't surprised actually. We've seen a few of these avian influenza viruses that have demonstrated a limited ability to pass from person to person. And so it's not unexpected that this new virus would also have that capacity. The question is is whether it will improve in its ability to transmit from person to person and therefore progress to a pandemic. And that's a very difficult question to answer.

HOBSON: Well, there are, so far, 133 cases - this is as of the end of June - being reported, 43 deaths. How serious is this at this point?

HORBY: Well, we've not seen any new cases recently. There was a large outbreak in April and March, and there has been one or two cases more recently, but it really seems to be well-controlled. And although the death rate is high, we have to understand that that's the death rate amongst mostly hospitalized patients. And probably there are other patients and people who are only mildly sick and so didn't actually come to the attention of the health care authorities.

HOBSON: Doctor, do you think that world health authorities are taking the precautions that need to be taken given what we know at this point? Does more need to be done?

HORBY: I don't think so. I think we've had a lot of experience with the H5N1 outbreaks, the bird flu outbreaks. There was a large outbreak of H7 - H7N7 in the Netherlands and then the pandemic in 2009. So, actually, the influenza experts globally are incredibly experience and that's probably one of the best researched viruses in the world. And I think the response is very well-rehearsed now, and there's a lot of research ongoing now to make sure that we can monitor this virus very closely and that we can respond appropriately.

HOBSON: Dr. Peter Horby is a senior clinical research fellow at Oxford. He's talking to us about a case of human-to-human transmission of the H7N9 bird flu in China. Doctor, thanks.

HORBY: Thank you. Transcript provided by NPR, Copyright NPR.