February 04, 2007

Bird Flu update

Up to now the only not art subject I comment on is the bird flu situation. With the first big UK outbreak of the season at the Turkey firm down south, I thought I'd return to it. The media will reassure everyone that the outbreak is contained and is not a threat to the population, which is true. Given our cultural disconnection from live fowl, the chances of it being caught in Britain are tiny. The threat is in the virus evolving across the species barrier in the far east or Africa. The latest news I read in the New Scientist was that it has made a significant leap into cats. This phenomen had already been noted - it had been killed a tiger in a zoo in Singapore, I think. But this latest research found thousands of cats had died from it in Indonesia. This is one of those worrying developments. Although much is unknown about the 1918 pandemic, there is evidence that there was a flu-like pandemic in pigs at the same time as the human pandemic. I've read some things that say it could have been human's that gave it to pigs, but more likely is that the virus jumped from birds to pigs and then to humans. Anyway, despite the media silence for months on the disease not reporting its movements around the world, it is always worth keeping an eye on http://crofsblogs.typepad.com/h5n1/

As I was born in 1960, I thought I'd selfishly celebrate this piece of research news from that site:
"Too old to catch H5N1?
Via CIDRAP, a very interesting letter to Emerging Infectious Diseases about the preference of H5N1 for young people: Avian Influenza A (H5N1) Age Distribution in Humans. Excerpt (citations removed and text re-formatted for easier reading):
Subject to multiple selection biases in the identification and reporting of WHO-confirmed human cases of avian influenza A (H5N1), our analysis yields 3 noteworthy observations:
1) case counts and case rates suggest similar levels of disease activity in the age categories 0–9, 10–19, and 20–29 years;
2) few cases have occurred above the age band of 30–35 years; and
3) the skewed distribution of cases toward children and young adults transcends sex, reporting period, patient outcome, geographic location, and, by implication, local cultural and demographic determinants.Behavioral factors increase the risk for exposure in younger persons and have been proposed as 1 determinant of the age distribution of confirmed human cases of avian influenza A (H5N1).
However, the possible role of biologic (immunologic and genetic) and other factors has yet to be determined. Such factors may include an age-related bias in case recognition, in which clinical suspicion about the cause of respiratory disease in older persons is lower.
Alternatively, we suggest that the 3 observations listed above are consistent with a biological model of geographically widespread immunity to avian influenza A (H5N1) in persons born before 1969, i.e., ≈35 years before the onset of the currently recognized panzootic in domestic poultry.
Such a model would account for the similar rates of disease activity in younger age categories, the sudden and pronounced reduction of cases in patients >30–35 years of age, and the age skew that transcends the sociocultural and demographic contexts of countries and continents.
The implication is that those of us who remember the 1960s (more or less) acquired immunity in our youth. That in turn implies an unrecognized worldwide exposure to some kind of influenza virus—perhaps in the 1958 pandemic—that conferred immunity to H5N1.
But I'm guessing here. I'd appreciate the thoughts of someone more informed than I."

No comments: