Beijing (AFP) - Doping is a "scourge" and "sport is dead" if track and field fans don't believe what they see, outgoing IAAF president Lamine Diack has warned in an interview with AFP.Speaking ahead of the vote by the 214 member federations of the International Association of Athletics Federations (IAAF) to choose either Sergey Bubka or Sebastian Coe as their new president, Diack told AFP of his admiration for Jamaican sprint star Usain Bolt, but also lamented the fact that doping remained a massive issue."When confronted with painful issues such as doping the IAAF have always stood firm and we continue to lead the way in this global fight against cheating," Diack insisted, with the world championships due to start on August 22 after the IAAF Congress."We will not let doping damage the credibility of our sport, and we will not stint in our crusade to have a clean sport, and to the extent of our investment and resolve in this respect athletics arguably leads the sports world's fight against this scourge. - Credibility vital - "The IAAF completely understand the importance of the credibility in competition.