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January 12, 2006

Is The Bird Flu Begining To 'Spiral Out Of Control'?

Topics: Health Issues

It appears that the H5N1 virus (bird flu) may be getting more effective at infecting humans, and the World Health Organisation believes that it is "spiralling out of control among poultry in Turkey" and is posing "a serious threat" to neighbouring countries.""


VIRUS-FLU-PANDEMIC-labels.jpg

[Image - illustration of a possible transformation from "fowl to human" to "human to human" transmission. Are we already there?]

In my humble opinion (one that I've had since Dec 10, 2004), this is a characteristic that we can expect to begin to emerge more often and in more countries and regions (some reasons for my somewhat gloomy predictions can be found in the extended post, below).

We have from The Scotsman:

[...] With 15 cases confirmed in humans in Turkey in the past week - compared with 140 in five years in the Far East - concern is growing that the disease may be evolving quickly.

"The virus may be spreading despite the control measures already taken. Far more human and animal exposure to the virus will occur if strict containment does not isolate all known and unknown locations where the bird flu virus is currently present."

The speed of the outbreak's spread prompted governments across Europe yesterday to guard against the disease.

Every human case was a chance for the virus to mix with human flu into a disease that is highly infectious as well as deadly, starting a pandemic.

WHO said that while it was not clear why so many people had been infected in Turkey so quickly, the virus might be starting to change. Guenael Rodier, who is leading WHO's mission to Turkey, said: "It is an open question if we are seeing a more efficient transmission from animals to humans."

Experts contacted by The Scotsman were not convinced this was happening, but added if the number of cases rose quickly to more than 100, it would be a sign of a significant alteration in the virus. They also expressed doubts that this would be a step closer to a pandemic form.

Also yesterday, a senior UN official urged countries attending an international conference on bird flu in China next week to pledge the £1.2 billion needed to help fight the disease worldwide by putting influenza programmes in place and controlling outbreaks in birds.

He added much more would be needed in the event of a pandemic.

However Professor Hugh Pennington, one of Britain's leading microbiologists, yesterday reiterated his call for the government to buy stocks of the existing vaccine.

He said: "Even if the vaccine is imperfect, I think the consensus view is it would save lives. It may not protect you from having the flu, but would perhaps give you a much better chance of getting through.

Meanwhile in Turkey, doctors were closely watching two brothers, aged four and five, who have tested positive for the H5N1 virus but so far have shown no symptoms of the disease.

With these excerpts in mind, and the WHO continuing to say "no problem, no pandemic concerns," let's recall that we've been hearing the same comments as the virus has spread step-by-step from it's beginings in Vietnam and China, to Europe and elsewhere.

From my post of December 10, 2004:

The CDC operates an Avian Influenza website. On the site you will find some background information about avian influenza, including recent outbreaks, the viruses, and the risk to human health.

At the CDC site there is a report on "Outbreaks in Asia" dated Nov 19, 2004 that contains the following paragraph;

As of November 18, 2004, there have been 44 confirmed human cases of avian influenza A (H5N1) resulting in 32 deaths. For more information about H5N1 infections in humans, visit the World Health Organization (WHO) website.

According to the same article, if these H5N1 viruses(avian influenza A) gain the ability for efficient and sustained transmission between humans, there is little preexisting natural immunity to H5N1 in the human population, and an influenza pandemic could result, with high rates of illness and death.

The following abstract from the research journal "Enferm Infecc Microbiol Clin. 2004 Aug-Sep;22(7):412-8, describes the situation as of Sept 04":

Avian influenza affects most types of birds and occurs in epidemics on poultry farms. The fatal disease is named "highly pathogenic avian influenza" and is caused by influenza A virus subtypes H5 and H7. The natural reservoir is the migratory waterfowl that occasionally infects domestic poultry. In 1997 in Hong Kong, 18 persons were infected and 6 of them died. At the end of 2003 and the beginning of 2004, avian influenza H5N1 infected numerous farms in several South-Eastern Asian countries. The virus was transmitted to humans in close contact with infected birds. A total of 34 persons were infected and 23 of them died. There is currently a considerable concern about the H5N1 avian influenza that has infected humans: the high virulence, evolution rate, the possibility of recombination with other influenza viruses, how H5N1 variants that infect humans or different approaches to the development of influenza vaccines. Source - PMID: 15355771(PubMed I.D.#).
As though this wasn't enough to alert us, according to "Proc Natl Acad Sci U S A. 2004 May 25;101(21):8156-61. Epub 2004 May 17," the hemagglutinin of recent human isolates has undergone significant antigenic drift.

Like the 1997 human H5N1 isolates, the 2003 human H5N1 isolates induced the overproduction of proinflammatory cytokines by primary human macrophages in vitro, whereas the precursor H5N1 viruses and other H5N1 reassortants isolated in 2001 did not.

This acquisition by the viruses of characteristics that enhance virulence in humans and waterfowl and their potential for wider distribution by infected migrating birds (unlike the precursor H5N1 viruses and other H5N1 reassortants of 2001) are causes for renewed pandemic concern.

I predicted then and I again do so, that we are going to hear much more about this in the (now ever growing nearer) near future.

And by the way, I have no crystal ball. But one need only look at the trends and the pattern, along with the nature of the virus taken within a historical perspective, to "guesstimate" that we need to look quickly toward developing an effective vaccine against the H5N1 virus, because the available antivirals aren't going to be much help. (And just think about how fast the common cold spreads throughout a community - multiply that a few times, and then add the fact that H5N1 can kill you, not just give you the sniffles). In the way of a disclaimer, I'm not a virologist, but do have a very strong background in microbiology and immunology. So for now, listen to the experts (I'm not one), but if it turns out that I'm right - I get to tell you that I told you so, if both of us survive.

Posted by Richard at January 12, 2006 9:28 AM



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