Brazil still has slavery?

After our discussions about slavery, it reminded me of a article I had previously seen, that Brazil is still releasing some of its citizens from slavery. Including releasing around 4700 slaves last year alone. Almost 400 years after slavery was first started in Brazil, they are still struggling to rid the country completely of slaves. My first thoughts are, how could this possibly still be going on in a country such as Brazil? As the 10th largest economy in the world, how can they still allow slaves in their country? Atleast since 2004 they have admitted that they have a problem and have sent out task forces to track down and release these slaves, I find it ridiculous that since banning slavery in 1888 they have not cracked down to completely eliminate it. As a country that is developing nation they should figure out and eliminate slavery before they are considered a world power, as they are on the way to becoming as one of the worlds largest economies. Here is a link to the article about the slavery.