By Brian Lowther
First, eradication is often confused with elimination. According to the Center for Disease Conrol and Prevention, to say that a disease has been eradicated means there has been "a permanent reduction to zero of the worldwide incidence of infection [from a specific disease pathogen]." And that, "intervention measures are no longer needed." Only two diseases have ever been successfully eradicated: smallpox and a bovine disease named rinderpest. Elimination is when a disease is no longer present in a specific geographical area, as is the case with polio in the United States.
Further confusion arises when the term eradication is used to refer to the complete removal of a disease pathogen from a person. This is known as "clearance of infection," and falls under the category of treatment.
Now, an analogy.
Picture a pack of a thousand people running at full speed toward a cliff that they cannot see. A handful of people stand a hundred meters from the edge of the cliff warning, "Turn back! There is a cliff up ahead!" Some of the runners turn back, but most don't hear the warning, or don't take heed and continue running. As the leaders of the pack near the precipice they finally notice the danger they are in and attempt to stop. But the momentum of the runners at the back of the group carries them over the edge into the ravine below. About half of the runners die. But, at the bottom are scores of people waiting with bandages, braces, crutches and the like for those who survive. In this analogy, we can think of medical practitioners and pharmaceutical companies as the people at the bottom of the cliff patching up the survivors. We can think of those who attempt to prevent disease and promote healthy living (nutrition, exercise, peace of soul and mind) as the people at the edge of the cliff warning, "Hey, there's a cliff here!" But working to eradicate disease is akin to removing the cliff altogether.
Ralph Winter often used another analogy:
It’s like walking through a sniper’s alley with a flack jacket. The flack jacket (prevention) will protect you from the sniper, but only so much. If you get hit, you’ve got to get the medic to remove the bullet and stitch you up (treatment/cure). But the most crucial objective is to eliminate the sniper (eradication).
In essence, eradication is treatment and prevention of a specific disease on a global level and for all future generations. Eradication can be thought of as preventing a given disease from infecting any human being on earth for the rest of history, rendering treatment forever unnecessary.