Comment on Post at Effect Measure
Revere:
Thanks for the insightful summary of the current H5N1 journey in Turkey.
As this situation evolves, it appears to be even more problematic as to when to make a decision to depoy to an isolation area, assuming this is even practical or warranted.
As usual, timing is everything and your posts are ever appreciated.
Michael
Good summary are usual Revere.
Would you like to put odds on each of the options?
Surely the sensible money would be on option 2 - seasonal flux?
Interesting coverage on the UK Channel 4 news last night - see it at: http://www.channel4.com/news/vid...deo/
monday.html
Agreed - an excellent overview of the situation and current explanations.
Regarding the liklihood that the case-fatality rate will fall as we detect less severe cases (the tip of the iceberg), Scott Dowell from CDC did seroprevalence studies around the family group in Thailand suspected of representing human to human transmission (mother-daughter-aunt)and found very little evidence that either villiagers or hospital workers had been infected with sub-clinical cases.
I like to see the options alongside the data that supports or goes against each of the options.
I don't like to be treated like a fool (even if I am at times, of course).
Thank you.
revere: thanks for your dedication this past year.
would a 5th possibility be that there is now better disease surveillance? when cases were reported earlier in the year, there wasn't widespread public recognition of the potential pandemic, and therefore (presumably), less pressure on gov'ts to report/seek out cases. are these new cases just due to ramped up public/gov't awareness? we may just be catching more of the denominator (while the numerator keeps increasing, too, unfortunately)....
And could it not be that the public is now really worried about bird flu so everybody with a sniffle is showing up at the hospital?
Cervantes, I would guess that's a big part of it. What we're seeing in Turkey is the mere shadow of what things will be like in a pandemic: hospitals jammed with people panicking at the first sign of a sniffle... and being sent home after picking up the real virus from someone who does have it.
Avoiding hospitals, unless you plan to stay, will be the best course of action.
student/cervantes: yes, of course, bias produced by increase awareness/recognition is a constant feature of outbreaks. But I am concerned here with actual cases. The first option would cover the false positives. But the idea is right on target.
trekie: not sure what you are asking for. If I can provide the info I will. I am traveling at the moment so blogging/email, etc., are a little more cumbursome and I can't always get to all the comments (or at least as many as I could if I were at home base), but I'll try.
MoM: I know Dowell's paper and there have been others of hospital workers. But a systematic seroprevalence survey in southeast asia and China still needs to be done (as the Japanese are doing with poultry workers). It is hard to understand what it hasn't been to date.
This is very useful, thank you Revere.
Re Option 1. The two youngsters near Ankara reportedly tested positive (though asymptomatic) after their only known contact was touching the gloves that Dad used to pick up a sick bird. If accurate, this would rule out the idea that all had very close contact with infected poultry.
Option 2: If this is just a seasonal upsurge, wouldn't we be seeing the same in SE Asia and China? But we're not and they're clearly on high alert now.
So, Option 3 is still looking most likely to me.
Increased awareness could also be a very relevant factor (the same two boys would never have tested positive in previous outbreaks), but this again would now apply in most places that have seen any kind of scare. So would transparency, and I'm very skepctical about Turkey's neighbours not having anything yet -- it just doesn't make sense.
Re mortality rate, I'm not terribly reassured re some cases producing mild symptoms (especially since I haven't played with chickens since I was a kid). And if hospitals are overwhelmed in a pandemic (vs. focussing all resources on saving isolated cases) many of those now being saved would die instead.
"trekie: not sure what you are asking for."
Sorry - my entry was meant as a compliment. I don't understand why WHO et al don't just do as you (revere) do: outline the posibilities, maybe in order or probability, but in any case treating the public (ugh, that's us!) as "intelligent though maybe not all that informed" people.
Why they don't, won't or can't do things in said way is open to it's own set of posibilities, of course.
Common sense would tell you the virus is now more B2H and H2H efficient. You do not need to do more than count the number of patients with pnemonia, high fever, and bleeding from the mouth.
Pleas do not use common sense. Instead, continue asking if there is any scientific evidence the glass is half full or half empty.
How do we know that there wasn't a larger cluster in China earlier that wasn't covered up? This is the largest known human outbreak, but perhaps nothing has changed at all except the venue.
o&b: Of course I meant the "known" outbreaks. I am quite confident there have been larger ones, either in China, souteast asia of Indonesia (and who knows where else?).
Hi, Revere. Question about seasonality and previous pandemics: Although of course the pandemics aren't seasonal in the sense of "annually recurrent at the same time of year," isn't it true that the pandemics of which we have record have arrived in the fall or winter (relative to each given hemisphere) and departed in the spring (again, relative to a particular hemisphere)? Of course, I acknowledge the possibility of the virus's returning the following year. It just seems that, in the northern hemisphere at any rate, if we happen to make it to late April without a pandemic, we can pretty well count ourselves reprieved until September. Do you agree that's about right?
Thanks,
Doug
Doug: Since we don't understand the basis of the seasonality I wouldn't be too confident given the sparsity of data points. The first wave of 1918 came in March-April (was mild) and the hammer came down in August. But your generalizations are mostly true. It may have something to do with the virus which seems to do best when the temps are below 20 degrees Celsius (68 Fahrenheit). Basically, we don't know.
The sequenced isolated from the fatal case acquired the HA S227N polymorphism (via recombination with H9N2 as predicted October 22) to increase transmission to humans
Efficient Human to Human Transmission Via H5N1 / H9N2 Recombination
Recombinomics Commentary
October 22, 2005
In the upcoming Virology paper "Evolution of the receptor binding phenotype of influenza A (H5) viruses, Gambaryan et al screen H5 isolates for affinity for human Sia2-6Gal (human-like) receptors. Two isolates, A/Hong Kong/212/2003 and A/Hong Kong/213/2003 were identified. Both isolates had the S227N polymorphism.
These two isolates were from bird flu patients who had returned from a visit to Fujian province, The daughter had died in China with bird flu symptoms. The two isolates were from her brother and father. The father subsequently also died. Thus, the change in receptor binding was associated with a familial cluster that probably involved human to human transmission.
Although the S227N change requires a simple G/A transition, it is rare. This is similar to another polymorphism E627K in PB2. The change is also encoded by a A/G transition, but is strictly conserved. E was exclusively in avian H5N1 isolates and K was found in all human isolates. The conservation could be explained by selection which may have been further restricted by opportunities for recombination. The conservation was broken at Qinghai Lake, where all 16 avian isolates contained the human E627K polymorphism.
Similarly, the lack of S227N in H5N1 may be related to a lack of recombination opportunities. As H5N1 expands its global reach via spread by long range migratory birds, the potential for new recombination targets generating novel genetic changes increases.
A search of the Los Alamos flu database using a 10 nucleotide probe representing the S227N polymorphism identified 42 exact matches. All were in HA and all isolated after 1998 were in the Middle East in chickens, turkeys, geese, and an ostrich.
H9N2 has become endemic in Israel and millions of migratory birds will be passing through the area in the upcoming days. Thus, the potential for dual infections by H9N2 and H5N1 is high. The 10 nucleotides of identity offers an opportunity for homologous recombination that would create the S227N polymorphism and increase the efficiency of H5N1 human transmission.
Efforts to limit the exposure of H9N2 infected birds to H5N1 infected wild birds should be aggressively pursued.
Isolates with donor sequences for S227N acquisition:
AY575869 A/Hong Kong/212/03 2003 H5N1
AB212054 A/Hong Kong/213/03 2003 H5N1
ISDN38262 A/Hong Kong/213/2003 2003 H5N1
AY575870 A/Hong Kong/213/2003 2003 H5N1
AY738456 A/ostrich/Eshkol/1436/03 2003 H9N2
DQ104453 A/turkey/Avigdor/1209/03 2003 H9N2
DQ104454 A/turkey/Avigdor/1215/03 2003 H9N2
DQ104458 A/turkey/Brosh/1276/03 2003 H9N2
DQ104455 A/turkey/Kfar Warburg/1224/03 2003 H9N2
DQ104464 A/chicken/Kfar Monash/636/02 2002 H9N2
DQ104450 A/turkey/Avichail/1075/02 2002 H9N2
DQ104473 A/turkey/Beit HaLevi/1009/02 2002 H9N2
DQ104451 A/turkey/Ein Tzurim/1172/02 2002 H9N2
DQ104462 A/turkey/Givat Haim/622/02 2002 H9N2
DQ104471 A/turkey/Givat Haim/868/02 2002 H9N2
AY548507 A/turkey/Givat Haim/965/02 2002 H9N2
AY738452 A/turkey/Givat Haim/965/02 2002 H9
DQ104459 A/turkey/Kfar Vitkin/615/02 2002 H9
AY548510 A/turkey/Kfar Vitkin/615/02 2002 H9N2
DQ104460 A/turkey/Kfar Vitkin/616/02 2002 H9
AY548511 A/turkey/Kfar Vitkin/616/02 2002 H9N2
AY548512 A/turkey/Mishmar Hasharon/619/02 2002 H9N2
DQ104461 A/turkey/Mishmar Hasharon/619/02 2002 H9
DQ104449 A/turkey/Naharia/1013/02 2002 H9N2
DQ104452 A/turkey/Sapir/1199/02 2002 H9N2
DQ104463 A/turkey/Yedidia/625/02 2002 H9
AY548513 A/turkey/Yedidia/625/02 2002 H9N2
DQ104448 A/turkey/Yedidia/911/02 2002 H9N2
AY548514 A/chicken/Tel Adashim/786/01 2001 H9N2
AY738454 A/chicken/Tel Adashim/786/01 2001 H9
DQ104465 A/chicken/Tel Adashim/809/01 2001 H9
AY548515 A/chicken/Tel Adashim/809/01 2001 H9N2
AY548500 A/chicken/Tel Adashim/811/01 2001 H9N2
DQ104467 A/chicken/Tel Adashim/811/01 2001 H9
AY548501 A/chicken/Tel Adashim/812/01 2001 H9N2
DQ104468 A/chicken/Tel Adashim/812/01 2001 H9
DQ104469 A/goose/Tel Adashim/829/01 2001 H9N2
DQ104470 A/goose/Tel Adashim/830/01 2001 H9N2
AY548499 A/turkey/Givat Haim/810/01 2001 H9N2
DQ104466 A/turkey/Givat Haim/810/01 2001 H9
DQ104472 A/chicken/Maale HaHamisha/90658/00 2000 H9N2
AY738451 A/turkey/Neve Ilan/90710/00 2000 H9
AY548502 A/turkey/Neve Ilan/90710/00 2000 H9N2
AF218108 A/Peking Duck/Malaysia/F20/1/98 1998 H9N2
AF218105 A/Peking Duck/Singapore/F91-5/9/97 1997 H9N2
AY206675 A/quail/Hong Kong/A28945/88 1988 H9N2
Commenting by HaloScan
