Full Idea
The eradication of smallpox is not viewed as an impoverishment of nature.
Gist of Idea
Eradicating smallpox does not impoverish nature
Source
Amartya Sen (The Idea of Justice [2009], 11 'Sustainable')
A Reaction
You'd have to be a pretty 'deep' ecologist to defend the carrier of smallpox, or Dutch Elm disease. The idea is included for balance.
Book Reference
Sen, Amartya: 'The Idea of Justice' [Penguin 2010], p.248