What has leprosy to do with this article about smallpox?
By the way, leprosy isn't as yet eradicated (although the direction of travel is encouraging).
https://en.m.wikipedia.org/wiki/Leprosy
Gordon, you really do seem to be slow this week. Smallpox declared eradicated by the WHO in 1980; leprosy declared eradicated by the WHO circa 1998. I happen to know that there have been a number of cases of smallpox since 1980, whilst - as you say - leprosy is still prevalent in a number of places of the world. Ironically, the number of cases of leprosy notified in Nepal ROSE in the 2 or 3 years following the WHO's declaration, partly because the work of various agencies has reduced the stigma that it used to carry, but partly because the international funding of leprosy treatment plummetted following the declaration.
I am aware that the work on smallpox reduction was dramatic and hard won, but its also worth noting that 'eradication' is rarely based on a 'no occurrence' basis, but on a reduction to less than a given prevalence basis.