RESUMO
Protective cross-reactivity between T. vitulorum and P. vivax was investigated in outbred albino rats. Protective resistance was confirmed in this model, especially when the trematode was given closer to the inflammatory period produced by T. vitulorum infection i.e. seven days prior to trematode administration. Such resistance decreased as the time between the two infections increased. Previous T vitulorum infection increased the induction of inflammatory reactions and influx of eosinophils but not mast cells. Serum and mucosal antibody responses to P. vivax adult and metacercarial antigens were more intense on previous exposure to T. vitulorum, especially seven days prior to trematode infection. The implications of these results with respect to protective resistance are discussed