Will H7N9 spread following the same pattern and timing as H5N1?

[AlaskaDenise]

Is it possible to anticipate where H7N9 will spread and when? One major difference, relating to successful tracking, is that H5N1 killed many birds making the spread obvious. H7N9 will be more difficult to track since it rarely kills birds, requiring more testing to uncover birds carrying this pathogen.

SCHEDULE:

first bird infections: H5N1=1996, H7N9=2013 or possibly earlier

first human infections: H5N1=1997 (stopped until 2003), H7N9=2013

first non-human mammal infections: H5N1=2003, H7N9=???

spread outside China in birds: H5N1=2004 (Mongolia, Turkey, Romani, Kuwait, etc.), H7N9=???

extensive bird spread outside China: H5N1=2006 (India, North Africa, Europe, South Korea), H7N9=???

more extensive bird spread: H5N1 (UK, Pakistna, Kuwait, Germany, France)=2007, H7N9=???

few more human infections: H5N1=2008 (China, Vietnam, Egypt)

continued birds and small numbers of human deaths: 2009 to present

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Can we look at H5N1's history to plot H7N9's future?

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[Giuseppe]

Re: Will H7N9 spread following the same pattern and timing as H5N1?

I think also the other influenza viruses acted as interference: H3N2 and possibly H1pdm09 circulated widely in Mainland China affecting several classes of age: for the older population, it could be the case that a reduced heterotypic immunity after natural infection with H3 strain opened doors to the new H7N9. For the work age groups, it would be interesting to see whether prior contact with poultry H5/H7/H9 determined an heterotypic immunity that older people can't manifest longer due immunosenescence and / or original sin...

In addition H1pdm09 would have likely pressured other animal viruses to adapt to other hosts.

In other words:

--- people born in the first half of XX century has been exposed to: H3NX, H1N1 (spanish flu), H2N2 & H3N2 - probably other H5/H7/H9;

--- people born between 1920 and 1958: H1, H2, H3;

--- people born after 1968: H3, H1, H5/H7/H9;

--- youngsters and children: H5/H7/H9, H1, H3...

[JJackson]

Re: Will H7N9 spread following the same pattern and timing as H5N1?

I am not currently expecting the same pattern of spread. Based on what what little we can infer about the source of infection I would guess it is a fit virus in birds generally, more so than H5N1, with a reservoir in wild birds. Human infections being caused by ducks and chickens just because they, as our main avian food source, provide the closest contacts. I would also guess that H7N9 finds it easier to get into mammals than H5N1. If it continues causing infections at its current rate then I would expect it to eventually generate an H2H capable form in someone. It seems to be a greater pandemic threat than H5N1 - in terms of event likelihood not impact. I suspect there is a mass of sub-clinical and ILI cases, yet to be discovered, which will greatly reduce the apparent virulence so while an H7N9 pandemic may be of higher probability it is not to be feared like an H5N1 based one.

[Giuseppe]

Re: Will H7N9 spread following the same pattern and timing as H5N1?

An human cluster just detected in Shanghai: a man confirmed positive after his wife was diagnosed with the virus on April 4. xhttp://rthk.hk/rthk/news/expressnews/20130413/news_20130413_55_914938.htm

[Laidback Al]

Re: Will H7N9 spread following the same pattern and timing as H5N1?

An human cluster just detected in Shanghai: a man confirmed positive after his wife was diagnosed with the virus on April 4. xhttp://rthk.hk/rthk/news/expressnews/20130413/news_20130413_55_914938.htm

Of course, this does not need to be human-to-human infection. Both individuals could have been infected from the same source.
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[JJackson]

Re: Will H7N9 spread following the same pattern and timing as H5N1?

Of course, this does not need to be human-to-human infection. Both individuals could have been infected from the same source.
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Is it clear which the case number is for the wife. I saw one female of a similar age and area (deceased) in the case list and the dates looked more like serial than parallel infection. You have to expect some H2H from very close contacts but that is a long way from saying there is sustained human-to-human transmission. At this point, given the number of cases, it is a little odd that a virus that seems to replicate happily in a human is having trouble jumping ship. This may be receptor binding specificity mismatch but if so how come it is successfully make the jump from its animal hosts, the binding problem would be the same and the contacts less frequent and less close.

[Shannon Bennett]

Re: Will H7N9 spread following the same pattern and timing as H5N1?

I think it is a more likely immediate threat than H5N1 but, I still believe that as some point H5N1 will also become a pandemic.

I am not currently expecting the same pattern of spread. Based on what what little we can infer about the source of infection I would guess it is a fit virus in birds generally, more so than H5N1, with a reservoir in wild birds. Human infections being caused by ducks and chickens just because they, as our main avian food source, provide the closest contacts. I would also guess that H7N9 finds it easier to get into mammals than H5N1. If it continues causing infections at its current rate then I would expect it to eventually generate an H2H capable form in someone. It seems to be a greater pandemic threat than H5N1 - in terms of event likelihood not impact. I suspect there is a mass of sub-clinical and ILI cases, yet to be discovered, which will greatly reduce the apparent virulence so while an H7N9 pandemic may be of higher probability it is not to be feared like an H5N1 based one.

[JimO]

Re: Will H7N9 spread following the same pattern and timing as H5N1?

Given that H7N9 has already acquired some of the genetic markers necessary to cause problems for humans, I also believe it to be an imminent threat, perhaps as early as next flu season in the Northern Hemisphere. It could persist through the summer like pH1N1 did in 2009. There is also stronger circumstantial evidence of H2H transmission that, if confirmed, appears more efficient than any suspected H2H transmission in H5N1.

[AlaskaDenise]

Re: Will H7N9 spread following the same pattern and timing as H5N1?

As was so well documented here on FT - the world watched H5N1 make a global spread in birds (mostly) before there were many small human clusters, while now we may have more small human clusters before it spreads global - even in birds.

Of course, in 1997 Hong Kong successfully stopped human spread by their massive bird kills which postponed the rare but sustained human infections for about 10 years. But now we cannot readily identify when H7N9 is present by seeing birds die and our only recourse is to test everthing that flies - which will be difficult, expensive, and always playing "catch up".

It will be interesting to see if this circulates in wild birds mostly in China for a few years until it is carried to the wild bird crossroad of Quinghai Lake - spreading it to the Middle East and Europe.

Giuseppe's points about prior exposures will be interesting to follow - especially if it is difficult to make a vaccine - anyone with exposures to other H7s or similar strains may fare better. That may mean that the people who "live" with chickens may do better as a group that all of the "genetically naive" populations with no exposure.

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[Lunabell]

Re: Will H7N9 spread following the same pattern and timing as H5N1?

AlaskaDenise-you might have a better idea about this than I since I suspect that you have lived in AK far longer than I have. My husband works in a village up on the Slope and migratory bird season is coming up. Last night we were discussing whether he should sit this one out based on what we know...and don't know at this point. What are your thoughts on that? Thanks!

[Laidback Al]

Re: Will H7N9 spread following the same pattern and timing as H5N1?

Lunabell - Welcome to FluTrackers.

I am sure AlaskaDenise will respond to you. But here are some things to consider when making your decision.

1. The exact infection source of H7N9 is not known. The carrier is presumed to be avian, perhaps domesticated poultry and/or wild birds.

2. H5N1 has infected more than 600 people since 1997. As AlaskaDenise notes, it is well documented that H5N1 is spread by migratory birds.

3. But even with all of that time, more than 10 years, H5N1 (HPAI version) has yet to be identified in Alaska or elsewhere in the western hemisphere.

4. If H7N9 continues to spread and moves from continent to continent, it will more likely be from human to human contact rather than contact with infected migratory birds.
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[AlaskaDenise]

Re: Will H7N9 spread following the same pattern and timing as H5N1?

AlaskaDenise-you might have a better idea about this than I since I suspect that you have lived in AK far longer than I have. My husband works in a village up on the Slope and migratory bird season is coming up. Last night we were discussing whether he should sit this one out based on what we know...and don't know at this point. What are your thoughts on that? Thanks!

Welcome Lunabell!

I believe your husband is perfectly safe. During the H5N1 outbreak, there was extensive testing of migratory birds in Alaska and none ever caused an infection. People who traditionally hunt and eat those same birds continued to eat them and none ever got sick. My slope worker neighbors have no intention of passing up those good jobs.

For myself - I'm going to be on a "kayaking marathon" this summer, trying to see how many (of the about 100) lakes in the MatSu borough I can kayak in one summer - I'll be going in and out of lakes on shores shared with migratory birds. I'm more concerned about washing my hands before eating to prevent salmonella.

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[Lunabell]

Re: Will H7N9 spread following the same pattern and timing as H5N1?

Thank you both! That sounds like a fun summer, AlaskaDenise! I will be spending mine in Homer getting our farmette up and running. My husband works for the school district up there and since he spends 3/4 of the year there, he claims it as his residence so he can subsistence hunt. It is good to know that there is little concern because the meat would be a welcome addition to the larder. As much as I love caribou, I am ready for a change!

[AlaskaDenise]

Re: Will H7N9 spread following the same pattern and timing as H5N1?

I expect AK Fish and Game will have bird testers out again, to check certain species.

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