Prevalence of equine Piroplasmosis and its association with tick infestation in the State of São Paulo, Brazil - Kerber, Claudia Ehlers; Labruna, Marcelo Bahia; Ferreira, Fernando; De Wall, D. T; Knowles, D. P; Gennari, Solange Maria (Revista Brasileira de Parasitologia Veterinária, 2009)