The strange epidemiology of Chinese bird flu cases

Earlier in the week we discussed the unfortunate 24 year old man who died of bird flu in Nanking in Jiangsu province. He had had no known contact with sick poultry. Now the father has bird flu. Did the father get it from the son? Did both get it from the same source? Or two different sources? Those are the open questions at the moment as Chinese health authorities struggle to follow up the health status of the father's 69 suspected contacts:

"The patient, a 52-year-old male surnamed Lu from Nanjing in Jiangsu, is the father of the serious case of bird flu diagnosed on December 2," said the statement posted on the health ministry website.

"On December 6, the China Disease Prevention and Control Center confirmed the presence of the H5N1 bird flu strain."

The man developed a fever and pneumonia symptoms on Monday while under medical observation following his son's death, the statement said.

The ministry added that all people who had been in contact with the older man were under observation but no new cases had appeared, and that it had promptly notified the World Health Organisation.

WHO spokesman John Rainford said cases of human-to-human transmission are very rare, citing only three previous cases in Vietnam, Cambodia and Indonesia.

Another WHO official, Christiane McNab, said 69 people had been in contact with Lu, and none seemed to have bird flu.

"If this is a case of contact between humans, the virus isn't virulent, otherwise other people would have been infected," she said.

Lu's son, 24, was hospitalised 10 days ago after developing pneumonia, Xinhua news agency reported at the time, citing Jiangsu health department. His condition deteriorated in hospital and he died on Sunday, Xinhua said.

The Chinese health ministry gave no further details on the condition of the new patient, whether he had had contact with poultry, nor any information on possible human-to-human transmission. (Agence France Presse)

The several days between these cases is suggestive of person to person transmission. With no history (so far) of contact with sick poultry but a definite contact with a sick person, this would seem to be the logical explanation. Except.

Except this seems to happen so very rarely. Fortunately.

Still, everyone, including WHO seems to be whistling in the dark on this one. It would be nice if people identified as "WHO officials" could use infectious disease terminology correctly. Virulence is the characteristic of producing severe disease in those already infected. Transmissibility is the ease with which infection is passed from a source to a susceptible contact. At this point no one knows if others have been infected (e.g., they may be incubating an infection or have mild or inapparent infection (which would require a more complicated and time consuming set of tests; it seem the contacts are only being watched for influenza like symptoms). No one seems to have fallen gravely ill.

The strange pattern of Chinese cases having no contact with sick poultry continues. The epidemiology of this disease in China seems quite different in that respect from Indonesia and most other places reporting human infection, although Vietnam, bordering China, has also reported a significant (but minority) proportion of cases without history of such contact.

This is one to keep an eye on. But they all are.

More like this

Given the demography of the Spanish flu deaths, Lu Sr. would have a much better chance of survival than Lu Jr., right?

Something about the virus triggering an over-dramatic immune system reaction, where someone with a really strong system (e.g. a 24-y-o man) runs a much greater risk of getting killed?

Martin: About 90% of cases are under age 40. This age shift to the left is typical of pandemic strains. The reason for the high case fatality is unknown. There is much speculation about the "cytokine storm" aspect of some of the cases, but what part this plays in all of this is so far unknown as well. We have written about it a fair amount here. Try clicking on Bird flu biology in the categories or just use the Google search bar on the blog itself (top left) and search under cytokine for more info. There is also a Flu Wiki entry we wrote a couple of years ago on the general biology of this.

Sounds like revere is obsessed with Flu Wiki. Every time this blog posts a message it always has to include Flu Wiki in the opening comment. Is revere the same as that dworkin guy too??

Wiki is impossible to navigate and I hate that site.

Brad,

Revere and the folks who started FluWiki are acquaintances. It is no secret to long-time readers. FluWiki does more in-depth coverage of Avain Flu stories than Effect Measure attempts to do. EM is more generally about the subject of Public Health, of which pandemic flu mitigation is just one part.

There are other Avian Flu websites and message boards that also discuss the various BF issues, so you have a choice.

By wenchacha (not verified) on 08 Dec 2007 #permalink

Brad: wenchacha has it exactly right. What isn't so obvious from your comment is that you are from Avian Flu Talk. I mention FW only occasionally (as an examination of the last hundred posts will verify) but since I was a founding editor there I am more familiar with it than other sites and it has a lot of information, some of which I generated (as in Cytokine Storm). And no, Greg Dworkin and I are two completely different people, although we are friends.

I find the internecine warfare between flu sites, sites that are working on the same problem, perhaps from different perspectives, a bit annoying. We have a big job to do. I am happy to have AFT try to do it in its own way and don't come over there sniping. You are welcome here, of course, but you could try to be more constructive.

revere is smarter than I am but I'm better looking (at least in Second Life, though that by its nature is subject to change). ;-P

There's room on the internets for everyone to approach this in their own way (especially given how much work there is to do on the topic). Trash talk helps no one. Why anyone would engage in it is beyond me.

In the meantime, the Chinese cases remain puzzling. Without epidemiologic field work and transparency, puzzling and perhaps misleading (only cases? milder cases in the vicinity despite a paucity of reports of same? how do we know?).

I'm worried about the delay in communication.
The father began presenting symptoms on Monday and was confirmed as having the virus on Wednesday. Press covered the news on friday.

"At this point no one knows if others have been infected". For sure we have to wait...

Revere:

I find the internecine warfare between flu sites, sites that are working on the same problem, perhaps from different perspectives, a bit annoying.

BRIAN:
Are you the Judean People's Front?
REG:
Fuck off!
BRIAN:
What?
REG:
Judean People's Front. We're the People's Front of Judea! Judean People's Front. Cawk.
FRANCIS:
Wankers.
BRIAN:
Can I... join your group?
REG:
No. Piss off.
BRIAN:
I didn't want to sell this stuff. It's only a job. I hate the Romans as much as anybody.
PEOPLE'S FRONT OF JUDEA:
Shhhh. Shhhh. Shhh. Shh. Shhhh.
REG:
Schtum.
JUDITH:
Are you sure?
BRIAN:
Oh, dead sure. I hate the Romans already.
REG:
Listen. If you really wanted to join the P.F.J., you'd have to really hate the Romans.
BRIAN:
I do!
REG:
Oh, yeah? How much?
BRIAN:
A lot!
REG:
Right. You're in. Listen. The only people we hate more than the Romans are the fucking Judean People's Front.
P.F.J.:
Yeah...
JUDITH:
Splitters.
P.F.J.:
Splitters...
FRANCIS:
And the Judean Popular People's Front.
P.F.J.:
Yeah. Oh, yeah. Splitters. Splitters...
LORETTA:
And the People's Front of Judea.
P.F.J.:
Yeah. Splitters. Splitters...
REG:
What?
LORETTA:
The People's Front of Judea. Splitters.
REG:
We're the People's Front of Judea!
LORETTA:
Oh. I thought we were the Popular Front.
REG:
People's Front! C-huh.
FRANCIS:
Whatever happened to the Popular Front, Reg?
REG:
He's over there.
P.F.J.:
Splitter!

--

H5N1 avian flu: Spread by drinking water into small clusters:

Human to human and contact transmission of influenza occur - but are overvalued immense. In the course of Influenza epidemics in Germany recognized clusters are rarely (9% of the cases in the season 2005).
In temperate climates the lethal H5N1 avian flu virus will be transferred to humans strong seasonal in the cold via cold drinking water, as with the birds feb/mar 2006.
Recent research must worry: So far the virus had to reach the bronchi and the lungs in order to infect humans. Now it infects the upper respiratory system (mucous membranes of the throat e.g. when drinking and mucous membranes of the nose and probably also the conjunctiva of the eyes as well as the eardrum e.g. at showering). In a few cases (Viet Nam, Thailand) stomach and intestine by the H5N1 virus were stricken but not the bronchi and the lungs. The virus might been orally taken up, e.g. when drinking contaminated water.
The performance to eliminate viruses of the drinking water processing plants in Germany regularly does not meet the requirements of the WHO and the USA/USEPA. Conventional disinfection procedures are poor, because microorganisms in the water are not in suspension, but embedded in particles. Even ground water used for drinking water is not free from viruses.
In temperate climates the strong seasonal waterborne infections like norovirus, rotavirus, salmonellae, campylobacter and - differing from the usual dogma - influenza are mainly triggered by drinking water dependent on the drinking water temperature (in Germany minimum feb/mar maximum august). There is no evidence that influenza primary is transmitted by saliva droplets. In temperate climates the strong interdependence between influenza infections and environmental temperatures cant be explained with the primary biotic transmission by saliva droplets from human to human with temperatures of 37.5°C. There must be an abiotic vehicle like cold drinking water. There is no other appropriate abiotic vehicle. In Germany about 98% of inhabitants have a central public water supply with older and better protected water. Therefore in Germany cold water is decisive to virulence of viruses.
In hot climates/tropics the flood-related influenza is typical after extreme weather and natural after floods. Virulence of Influenza virus depends on temperature and time. If young and fresh H5N1 contaminated water from low local wells, cisterns, tanks, rain barrels or rice fields is used for water supply water temperature for infection may be higher as in temperate climates.

Dipl.-Ing. Wilfried Soddemann
eMail soddemann-aachen@t-online.de

Hey - Soddemann psted identical 'drinking water' story over on Avian Flu diary. Don't know if this is someone peddling pet theory (conspiracy or otherwise) bu thought I would pass it on.

Contaminated water arising from bird feces that have H5N1 is definitely a possibility, but so are unknown animal reservoirs, although I think these are only operating in places like Indonesia and China. In the UK and other European countries the spread is more likely due to people walking in contaminated fecal dust, in my opinion, whether initial infection came via bird migrations or other factors.

Revere --

Is the lack of contact with poultry really so unusual, or just the confessed lack of contact? It's seemed for awhile that Indonesian cases are all declared "close" to sick birds, whether that means next door or two blocks over.

And in a country where B2B H5N1 has become endemic, and so much of the population keeps birds/poultry, it's almost always possible to find a link... whether it's the actual source, or not.

caia: I think it is different. It is not just lack of contact with poultry (Chinese cases have contact with poultry, just as you and I probably do, at least in the market). It is that except in one case there are no sick poultry anywhere around, i.e., the Chinese cases do not occur in the context of sick birds in the vicinity anywhere. So if birds are the source, they are not obviously sick birds.

Hmm. Do you suspect vaccinated birds, humans, some other reservoir/carrier...?

revere,

You are right. This pattern of having cases with no apparent poultry outbreak appears to be unique to China, even from the small number of cases reported. In Indonesia and other places, they might tell you that the patient did not have direct contact with poultry but most of the time they will also add that there is a history of poultry die-offs in the area. Whether that is due to attempts by officials to deny any possibility of h2h is anybody's guess. But the thing is, there is a distinct difference with the situation in China where there are NO history of poultry die-off at all!

The epidemiology of this disease in China seems quite different in that respect from Indonesia and most other places reporting human infection, although Vietnam, bordering China, has also reported a significant (but minority) proportion of cases without history of such contact.

I haven't followed the virology too closely these past few months, but what happened to the Fujian-like strain in China that Webster and Guan Yi wrote about last year? My understanding was that that strain appear to be spreading to Vietnam and Thailand. What's your take on that?

It aint unique to China Susan if H2H is underway where the media can report it. Boxun.com sent several reporters to jail for LIFE for reporting information that they couldnt back up. Of course they were not allowed to call witnesses or present evidence, but its China now isnt it?

I cant remember whether you were here back when but several villages like three years ago just disappeared. The PRC rep when questioned about where the people were by the WHO guy investigating the first hit of H5 in China said that they were flooded out. The WHO rep who had been there for SARS said what flood? They were at the 3200 foot level and the nearest river was a couple of miles away.......Boxun reported them by names, conditions and etc. Apparently PLA trucks pulled up when they knew they had BF, loaded them up and took them to the border of the Mongolian Gobi. They left them there in tents, with food, water, and no doctors. They did have guards apparently. The Gobi forgives nothing.

By M. Randolph Kruger (not verified) on 10 Dec 2007 #permalink

After a life-time of tracking animal pathogens in the field, the conclusion I have reached is that we only see a fraction of what is going on in nature...most is beyond our six senses.

In my opinion, a pandemic with very serious consequences for humanity is imminent. However, Dr. Nabarro said it best...'we are on nature's time'...and that could be a while.

It's easier if one keeps in mind that...nature's patterns and behaviour often defies logic.

The Indonesian Tsunami is one case in point.

How come did they test this case, if it was only two people having pneumonia, and no sick poltry contacts at all... Do they *really* test all this kind of cases in China for H5N1? Quite impressive! ;)