eradicate and eliminate

Etymology does help in seeing the difference between these two words.  It isn’t always the key but in this instance it does work.  To eradicate a plant is to pull it out by the root which, as every gardener knows, is the best way of making sure that it never grows again. The Latin is e-  (from ex-) meaning ‘out’ and radix, radic- root.  So if you eradicate a disease you mean that you have wiped it off the face of the earth. Eradication is global. Only two diseases have been eradicated and they are smallpox and rinderpest (a disease of cattle).

 To eliminate something is, in its literal sense, to throw it out.  The Latin is e- (from ex-) meaning ‘out’ and limen threshold.  Basically you turf it over the threshold and out of the house.  So to eliminate a disease is to get rid of it from a defined geographical area.  This means getting down to zero or almost zero cases.  There might still be one or two instances that might pop up but these can be dealt with easily.  For the bulk of the population the disease is no longer a threat.

 Recently New Zealand claimed that they had eliminated COVID-19, a cause for much rejoicing.  They of course do not claim that COVID-19 is eradicated because that is something that the rest of the world has to achieve.  

 There is a third term in this set and that is control.  If you control a disease then you have ways of protecting a population from it even though you can neither eradicate nor eliminate it. Malaria is an example of a disease that is controlled, either by public health measures such as making sure that there is no water left lying around near houses and that mosquito nets are used, or administering treatments as either prophylactics or cures.