by Juliana Ruhfus, Al Jazeera, Qatar - Every year tens of thousands of West Africans migrate to Europe in search of a better life. But for some of them that search will end in tragedy, as they fall victim to competing mafia gangs that prey on the hopes of the desperate. In southern Italy, it is Nigerian women who are among the most exploited, with many ending up trapped in the nightmare world of the sex trade.