Long-lasting antibodies detected by a trans-sialidase inhibition assay of sera from parasite-free, serologically cured chagasic patients.

A test based on the inhibition by antibodies of the trans-sialidase was used to analyze infection by Trypanosoma cruzi, the agent of Chagas' disease. Sera collected during the longitudinal follow-up of benznidazole-treated acutely and congenitally infected patients became negative for T. cruzi as determined by tests presently used to assess cure; however, the sera remained positive for T. cruzi by the trans-sialidase inhibition assay (TIA) up to 14 years after treatment. Therefore, TIA is a highly sensitive marker for previous T. cruzi infection.