"There are only two ways of telling the complete truth—anonymously and posthumously."Thomas Sowell

Thursday, November 03, 2005

Undue In-Flu-Ence

I am watching the coverage of the HHS/DHS influenza pandemic plan with a mixture of interest and foreboding. As usual, the mainstream media coverage of a medical risk issue is histrionic and completely devoid of context; I see that several particularly unhelpful infobites are becoming set in concrete and passed from story to story like some, but not all, influenzas pass from person to person.

First, it is unfortunate that planning for a hypothetical influenza pandemic has become conflated in the popular imagination with the H5N1 avian influenza strain. There is no reason to believe that this strain is any more likely to be the precursor of the next pandemic than a couple of dozen others. And there's nothing to be gained from leading people, especially in North America, to believe they are at risk from existing avian flu. People who have no contact with live birds are looking askance at frozen Butterball turkeys, for crying out loud.

It would be a very bad thing were H5N1 avian influenza to appear in the United States, but it would mainly be a bad thing for poultry farmers and consumers. The health risk would be confined to the effect of increased chicken and turkey prices on nutrition; the conditions under which poultry is raised and processed in this country are so vastly different than conditions in Asia, both in terms of veterinary oversight and simple hygiene, that it is unlikely that disease would spread even to those in closest contact with the potential domestic reservoir.

Second, the constant repetition of "three pandemics this century" neither provides the context of how bad these pandemics were in relation to an ordinary flu season, nor explains the relevant changes medicine and culture have undergone in the intervening years. Of course, there is renewed interest in the history of the 1918 influenza epidemic, which killed somewhere between 500,000 and 600,000 Americans in less than eight months, and then apparently disappeared. Comparisons are made between this event and a potential pandemic today, without the following clarifications:
  • no one in 1918 knew that this epidemic, or influenza in general, was caused by a virus, much less which virus, and obviously there were no vaccines or antivirals for any influenza strain;
  • the antibiotics to treat the secondary baterial infections which cause the majority of influenza deaths were unknown;
  • tools to track geographic spread were crude to nonexistent;
  • the mechanism by which the virus mutated into its suddenly lethal form -- the transmission of a moderately virulent strain from Kansas to Europe via troop movements, its incubation in the crowded and filthy war zones of Europe, and its retransmission from there to multiple destinations, again accompanying troop deployments -- was almost certainly a unique confluence of historical events;
  • some evidence exists that the extreme virulence of the 1918 influenza was greatly exacerbated by the high prevalence of tuberculosis in the general population, a condition that no longer exists in the United States (although this would certainly be an important factor in a global influenza pandemic).
The other two epidemics that are lumped with 1918 are the 1957 outbreak of Asian flu, and the 1968 Hong Kong flu. In both these cases, the virus was identified about six months before the first cases were observed in the United States, vaccine preparation was possible, community based public health surveillance was on alert, and consequently the death toll was much, much lower. In 1957 there were about 70,000 deaths, and in 1968 fewer than 35,000. The deaths were, as is usual in ordinary influenza years and in contrast to 1918, concentrated in the over-65 population. The total deaths were higher than usual but nothing like the mortality in 1918.

So why is the press treating the next pandemic as 1918 redux, rather than the less scary, but more plausible, recent history of novel flu strains? I'm open to suggestions less cynical than the ones that immediately come to mind.


James Elliott said...

Uh, cuz it keeps the viewership figures down and prevents the ad-dollars from flowing?

Oh, wait, that was the cynical version. Let me try again:


Tlaloc said...

"So why is the press treating the next pandemic as 1918 redux, rather than the less scary, but more plausible, recent history of novel flu strains? I'm open to suggestions less cynical than the ones that immediately come to mind."

Well Kathy while you raise good points about the various factors that will be better impediments to a pandemic these days you neglect the various ones that might exacerbate such a problem.

For instance the US population in 1918 was about 100 million. It's of course closer to 300 million today. Meanwhile the world population was 1.8 billion and today is 6.5 billion. Naturally having a larger population means both a substantially increased death count for the same mortality rate and the risk of higher mortality rates based on closer proximity and therefore easier spread of the contagion.

Furthermore the 1918 flu killed about 25 million worldwide in the staggeringly short time of 6 months. Naturally 1918 was a time before commercial air traffic. Modern international airports pose the threat of being enormous disease vectors allowing a disease to create nearly simultaneous hotzones world wide.

The median age today is almost certainly far higher than it was in 1918 meaning that a greater percentage of the US population are especially at risk.

Just a few tidbits going the other way to savor.