3. Your Website’s Content Got “Scraped”
If your rankings suddenly deteriorate, that could be because someone has stolen (or “scraped”) the content from your site and posted it somewhere else on the Web. In this case, search engines sometimes lower both sites’ rankings – then look deeper into the matter. Eventually, they are likely to start ranking your site as high as they used to before the incident, once they realize who copied whose content. However, this may take some time.
The Way Out
Dealing with content thieves normally involves locating the site that posted your content, contacting their webmaster, emailing their host, filing a DMCA (Digital Millennium Copyright Act) request or taking the matter to court – whatever helps. It’s recommended to start with contacting the scrapers. If this does not help – take the other measures mentioned here.
via Rankings Dropped? 9 Possible Reasons and 9 Ways Out | The Ad Master – Advertise Everywhere.
Wikipedia: Web Scraping
Blue Glass: Content Scraping: Prevention, Repercussions, and… Benefits (Good information but has some link rot).
Perishable Press: How to Deal with Content Scrapers
The Blog Herald: The Six Steps to Stop Content Theft
Magnet4Marketing: 4 Ways to Help Prevent Content Scraping from Happening on your Blog