Sure they do - in fact, the US and Russia are not destroying the last of the smallpox "for the foreseeable future":

http://www.telegraph.co.uk/health/healthnews/8267370/We-must...

This results from an anthro-centric cost/benefit analysis, not just a "save the poor deadly organisms", but I expect the same would be true for just about any organism that human science can maintain, and attempts to destroy.