The Riddle of the Ages
#231
One of the great unanswered questions about the H5N1 Bird Flu virus is why, out of roughly 258 known human infections, have nearly 90% been in people under the age of 40?
This is, to many pandemic flu watchers, the most horrifying aspect of the Avian flu threat: The idea that our children, and our grandchildren could be the biggest victims.
As to why this should be, theories abound, but to date, no one really knows the answer.
It has been suggested that children are more likely to have close contact with infected birds, either through playing with them, or caring for them, but the high incidence of cases among those over the age of 20 would seem to belie that argument. The number of infections in ages under 20 is almost exactly the same as the number of infections between the ages of 20 and 40.
Demographically, the median age of the inhabitants of countries thus far affected countries is lower than in the western world, and that too may skew the figures, but once again, not enough to account for the numbers we’ve seen.
And even more distressing, the trend suggests that younger patients, those with presumably the healthiest immune systems, are most likely to succumb to the virus if infected.
Among those aged 10-19 thus far been infected, 74% have died. Teenagers have demonstrated the highest mortality rate. Compare that to all those infected over the age of 40, where just over 36% have died. Clearly, the H5N1 virus has demonstrated an affinity for younger hosts, and this has huge implications if this trend should continue.
Influenza is generally thought of as being a relatively benign illness among healthy individuals, and while producing tens of thousands of deaths each year, it is primarily a scourge of the elderly or those with weakened immune systems. The Avian flu, much like the Spanish Flu of 1918, seems to defy this conventional pattern.
The dominant theory is that a novel virus, one that humans have little or no immunity to, produces an overwhelming and often deadly immune response in the healthiest of victims. Those over the age of 40, at a time in their lives when their immune system is naturally on the decline, are therefore less likely to succumb to the disease.
It has been suggested that this over active immune response, dubbed the `cytokine storm’, is what actually kills most Avian Flu victims. The body rallies its defenses against the viral invader, sending a massive flood of antibodies to the site of infection, usually the lungs, and we literally drown in our own defenses.
We’ve seen this before, in the 1918 Spanish Flu. During that pandemic, those over 65 actually died at lower rates than would have been expected in a normal flu year, while those under the age of 40 died at a rate many times higher than would be expected.
Once again, there are many theories for this, but no one really knows why. Did an earlier pandemic of a similar virus confer immunity to those who had been alive in the 1850’s? Or is this simply more epidemiological evidence for the cytokine storm theory?
While it is too early in the the genesis of the H5N1 story to draw firm conclusions as to how a future pandemic would present itself, we do have disturbing indications that a repeat of the 1918 pandemic, and its affinity for younger victims, are possible.
Beyond the vicious nature of any disease that targets the young are the implications to the developing world, where the median age can often be as young as 18 years of age. Countries already ravaged by poverty, AIDS, famine, and TB could take a much harder blow from this pandemic than the western world. A country like Nigeria, for example, with a median age half that of the United States, could conceivably see double the mortality rate.
Asia, Africa, and the mid-east, due to reasons of demographics alone, are particularly at risk during a pandemic.
And if a pandemic comes, it will come to the entire world pretty much simultaneously, and help from the western world will likely be sparse. Countries will understandably be dealing with massive problems of their own during a health crisis, and their ability to extend aid to other countries will be limited.
A severe pandemic is more than a public health crisis. It has the potential to alter the geopolitical face of the globe for generations to come.
