[Anti-F2/3 antibodies as cure marker in children with congenital Trypanosoma cruzi infection].

The F2/3 antigenic fraction isolated from Trypanosoma cruzi trypomastigotes contains epitopes recognised by antibodies which are representative of active infection. The kinetics of disappearance of conventional serology (CS) and anti-F2/3 antibodies were compared in 21 patients with congenital Chagas disease after receiving benznidazole treatment. Patients were divided into 2 groups: (A) Age < 8 months at diagnosis; (B) Age > 9 months at diagnosis. Group A presented negative outcome for CS at 6.6 mo. (CI95 3.4-9.8 mo.) and for anti-F2/3 at 4 mo. (CI95 0.9-7.1 mo.), p = 0.18. Group B exhibited non-reactive CS at 63.1 mo. (CI95 42.1-84.2 mo.) whereas anti-F2/3 antibody determination became negative at 21.9 mo. (CI95 5.7-38.1 mo.), p = 0.0025. In patients belonging to group A, antibodies were undetectable by both CS and anti-F2/3 ELISA soon after receiving chemotherapy. In infants included into group B, a negative result for anti-F2/3 antibody detection significantly anticipated the disappearance of CS reactivity. Consequently, an anti-F2/3 antibody assay becoming negative should be considered as an early marker for assessment of cure, particularly in those patients with prolonged time of infection.