Harm reduction outreach workers on the field :: contributions and challenges - Ferreira, Elza; Mamude, Marcia; Trigueiros, Daniela; Bueno, Regina; Abbate, Maria Cristina; Mesquita, Fábio; Gryschek, Anna Luíza de Fátima Pinho Lins (International Conference on the Reduction of Drug Related Harm, 2004)