Human toxocariasis: frequency of anti-toxocara antibodies in children and adolescents from an outpatient clinic for lymphatic filariasis in Recife, Northeast Brazil - Santos, Ana Maria Aguiar; Andrade, Luiz D.; Medeiros, Zulma; Chieffi, Pedro Paulo; Lescano, Susana Angelica Zevallos; Perez, Emilia P. (Revista do Instituto de Medicina Tropical de São Paulo, 2004)