We will never, ever destroy TB. There are simply too many animal hosts for the disease. Hell, you can get it from your dog (http://www.petplace.com/dogs/tuberculosis-in-dogs/page1.aspx). The reason we could get rid of smallpox, the only reason, is that smallpox is a disease found only in human beings. There aren't a whole lot of diseases like this. Polio is one, I think.

But most communicable diseases that afflict humans can also be found in animals. Influenza, plague, leprosy... good luck on those.