• Escape of the Pathogens
• Antibiotic resistance
• HIV

The Escape of the Pathogens: An Evolutionary Arms Race (1 of 2)

Human populations are constantly locked in evolutionary arms races with pathogens that invade our bodies. We must recognize that these pathogens (such as the flu virus shown at right) are continuously evolving entities in order to develop better ways to fight them and control their evolution.

An ounce of prevention...every year?
Recently, the mayor of New York City called upon citizens to get a head start on one particular evolutionary arms race: “I urge older New Yorkers and others at risk to protect themselves from flu and pneumonia through a simple and proven ounce of prevention: immunizations. The time to get immunized is now, before the peak of the flu season.”¹

Many of those New Yorkers had already gotten flu shots the year before and the year before that, but, perhaps strangely, they were being asked to get yet another immunization. Why do we need a new flu shot every year? Can’t modern medicine invent just one vaccine that would do the trick?

Flu viruses evolve rapidly.
As they circulate through populations around the world and switch hosts, flu viruses change so much that our vaccines are rendered obsolete every year. The flu is a problem for which a solution must be redesigned and rebuilt every year, like a bridge that gets washed away every flood season. Only by understanding the flu as an evolving entity can we understand why our solution to the problem must change every year.

• Transmission electron micrograph of a flu virus, courtesy of the CDC.
• Photo of scientist studying pathogens courtesy of the CDC.
¹ NYC Dept of Health press release, October 22, 1998