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ICG Risk Blog - [ The flu season not yet underway and uncomfortable signs that 'when, not if' is shifting to 'soon, not when' ]

The flu season not yet underway and uncomfortable signs that 'when, not if' is shifting to 'soon, not when'

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A Thai teenager that died in Thailand of avian flu was "was an 18-year-old male who'd been exposed to sick chickens… had very close contact to . . . fighting cocks by carrying and helping to clear up the mucous secretion from the throat of the cock during the fighting game by using his mouth.

That is, the young man -- in a move not uncommon in cockfighting circles -- had cleared the cock's airway by sucking his rooster's beak and then swallowing the spit and mucus. ''That was a risk factor for avian flu that we hadn't really considered before.'' -- WHO Disease Outbreak News, ProMED-mail

A fine example of why scenario planning does not work as no matter how many scenarios one spins, as it will be one not envisioned that will deliver the payload. Only rigorous, timely, and accurate procedural analysis will work, but in a repeat of the SARS debacle, governments are voting their short term economic gains over recognition of the pandemic on their doorstep by reducing the flow of accurate infection information and slowing the entry of foreign epidemiologists.

The globe is statistically overdue for another influenza pandemic such as the one in 1918 that killed 20 to 50 million worldwide. In Will it take a second pandemic to move flu vaccines from private enterprise to national defense?, I predicted that "flu vaccines in the developed world will follow the trajectory of AIDS drugs in the third world: similar lethargy, death toll, threats to bypass patents to produce generic substitutes, and finally various forms of production and/or resale agreements that allow wider local ministration to the disease" even as the avian influenza strain A(H5N1) "continues to kill the majority of people it infects." The medical chatter is increasingly uncomfortable in that feeling of when, not if is shifting to soon, not when. The 70-odd members of the CDC influenza team are the US’s "first -- and in a worst-case scenario, last -- line of defense" against another influenza attack.

Between January and the end of October, 32 people have died from avian influenza in Vietnam and Thailand. Tens of millions of chickens have succumbed. Millions of others have been slaughtered. More nations have admitted to outbreaks among birds in more provinces than would have been conceivable even 18 months ago.

Events in Asia, in particular, are escalating almost daily, with more human deaths, more different species becoming infected and more questions arising about how the virus there behaves. At the same time, some governments in the region are remaining closemouthed about what is happening within their borders.

It is useful to understand the classes of subgroups of flu:

Influenza viruses are divided into three types: A, B or C, depending on the virus structure. Humans can be infected with all three, although C-class flus are uncommon and influenza B doesn't usually cause severe illness except among children. Influenza A is the monster, in both animals and people, causing, by and large, the most virulent illness. Type A influenzas (unlike B's or C's) have multiple subtypes: H3N2, H1N1, H7N2. The ''H'' is for hemagglutinin, a spiky protein on the surface of the influenza molecule. In human flu viruses, the spikes of hemagglutinin [connect] with matching receptors on the outside of healthy respiratory-system cells. The virus then melds with the healthy cell and begins replicating. Neuraminidase, the ''N'' in the flu name, another protein, uncouples the virus from its host, tearing the cell membrane and allowing the progeny to escape, killing the cell. Loosed, they start repeating the process deeper and deeper into the respiratory tract.

Whereas the 1997 Hong Kong H5N1 averted a pandemic when authorities, acting on data confirming the causal link between fowl and humans, called for the immediate killing of all fowl, the 2003 SARS outbreak became ''interpolated with economic and political concerns'' when Beijing denied there was a problem, doctored the data, and tried to bluff its way out. This latter pattern is now being duplicated in Viet Nam and Thailand in 2004, but unlike SARS which had a relatively infection rate, an avian pandemic under similar dissembling may run riot. This 2004 event is avian flu, H5N1. By infecting house cats and pigs, and being the first avian flu transmittable cat to cat, it has shown a strong ability to infect mammals.

Pandemics require (a) a new human influenza subtype to which the infected will have no developed immunities, and (b) efficient person to person transmission. While many strains of influenza A circulate in birds, three have caused a pandemic when introduced into humans:

The catastrophic 1918 Spanish flu pandemic was caused by H1N1. The 1957 Asian flu pandemic, which killed 70,000 in the United States, was brought about by H2N2. And the 1968 pandemic of Hong Kong flu introduced H3N2. That outbreak killed about 34,000 people in the United States.

Lack of data and access shroud the transmission vectors, why it stops and starts, why more poultry workers haven't fallen ill, and how H5NI is mutating. Asian reluctance to look for avian flu may mask the moment when an epidemic passes into a pandemic.

We are running on chance.

The Flu Hunters
By Gretchen Reynolds
New York Times
November 7, 2004

Communicable Disease Surveillance & Response (CSR)
Disease Outbreak News
WHO

ProMED
Federation of American Scientists

Gordon Housworth



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