Designing Advanced Nanomedicine
As an estimate, scientists are probably 10 years from building proof of concept nanomachines of the sort proposed by Robert Freitas, or shown in this Nanotechnology News Network article. It'll be at least another decade after that to proceed to mass production - but the benefits will be astounding. (Poorly) translated from the Russian: "How we can see, proposed worm design can collect and digest more microorganisms than microbivore. It can move in blood, so it will multiply number of collected bacteria. Nanorobot in bloodstream can collect bacteria and fungus. Worm can also crawl on the tissue surface, so I can imagine worms, crawling on vein's surface to clean out atherosclerosis conglomeration. Worm will be constructed from diamondoid with high precision molecular assembling technology. Worm tracks technology allows fully reprogrammable binding sites, which can make Worm multipurpose device - it can collect not only bacteria or viruses, but toxic enzyme too."
Link: http://www.nanonewsnet.com/index.php?module=Pagesetter&func=viewpub&tid=4&pid=13