Saturday, March 18, 2006


This just posted on Al Jazeera (though I imagine it will soon be flying through the news world): Bird flu kills woman in Egypt.

What are we to make of this bird flu thing? It appears that there is no cure for bird flu - at least not yet. The Egyptian woman was given Tamiflu but still died two days after her symptoms appeared, and not long after she reported having infected chickens.

My grandmother in Chicago once told me that a third of her family died in the 1918 flu epidemic. Worldwide, it killed tens of millions. The Center for Disease Control in Atlanta says that another global flu pandemic is inevitable.

In Plague Time : The New Germ Theory of Disease, Paul Ewald argues the theory of evolutionary epidemiology, in which disease is seen as an adapting force following Darwinian laws. Whether it's a parasite, cancer or virus, the goal of a disease organism is to survive and produce more offspring than competing organisms. In many cases these organisms reproduce rapidly, and so the evolution is very rapid. We can predict, and potentially control, the progress of the organism by understanding the conditions in which it develops.

For example, Ewald has discovered that when cholera exists in an environment where it is not widely spread, it becomes more benign. This makes sense because it must keep its host alive in order to spread. When it is in a place where there is unclean water and it can spread rapidly, the virus is much more virulent because it can kill the host and still be transmitted.

Ewald says that the 1919 flu virus became as virulent as it did only because it grew in the trenches of the Western front during WWI and then was carried home by soldiers as they were demobbed. He says, "Such conditions must have favored the predator-like variants of the influenza virus; these variants would have a competitive edge because they could ruthlessly exploit a person for their own replication and still get transmitted to large numbers of susceptible individuals. These conditions have not recurred in human populations since then and, accordingly, we have never had any outbreaks of influenza viruses that have been anywhere near as harmful as those that emerged at the Western Front. So long as we do not allow such conditions to occur again we have little to fear from a reevolution of such a predatory virus."

Ewald believes that bird flu will not result in the deadly pandemic that the CDC is predicting. That's good news. My one concern with his analysis is whether there is no place in our diverse world that might provide the right conditions to develop a killer virus, but of course there would also have to be a rapid mode of transmission akin to WWI demobbing that could spread the disease before it mutates into a less harmful form. If Ewald is right, the bad news is that we're squandering resources on false threats like bird flu when we could be using them to fight diseases that are currently wrecking millions of lives.

Ewald believes that evolutionary epidemology will lead to the eradication of many of the health problems of our time, possibly including cancer, AIDS, malaria, and diabetes, at very little cost. His caution is that there is going to be big time push-back from the pharmaceutical industry, biomedical researchers, and even health professionals, all of whom may become much less necessary in society. Ewald warns that his approach "does not mesh nicely with the profit motive of the free market." Therefore, government priorities and funding are going to have to change if this new approach to disease is going to be successful.


No comments: