TRYPANOSOMA-CRUZI DEFINED ANTIGENS IN THE SEROLOGICAL EVALUATION OF AN OUTBREAK OF ACUTE CHAGAS-DISEASE IN BRAZIL (CATOLE DO ROCHA, PARAIBA)

Immunoglobulin G and M humoral response to recombinant protein B13 and glycoconjugate LPPG Trypanosoma cruzi defined antigens was evaluated by ELISA in 18 patients in the acute phase of Chagas disease, who were contaminated on the same occasion. LPPG showed 100% positivity detect ing both IgM and IgG antibodies, while positivity of 55-65% was observ ed for B13. An epimastigote alkaline extract (EPI) also showed high se nsitivity for acute IgM (100%) and IgG (90%) antibodies. However LPPG had better discriminatory reactivity since with EPI two patients showe d negative IgG and several other sera presented OD values for IgG and IgM antibodies very close to the cutoff Thus, it is suggested that det ection of IgM antibodies by LPPG may be used for diagnosis of the acut e phase of Chagas disease. An intense decline of IgG and IgM antibodie s to the three antigens was absented in response to anti-T cruzi chemo therapy in all acute phase patients. After treatment, six (30%) indivi duals maintained IgG positivity to EPI, LPPG, and B13 with lower react ivity than that measured at the acute phase. For comparison, serology of a group of 22 patients in the chronic phase of Chagas disease and a lso submitted to chemotherapy was determined. Positive IgM antibodies to EPI, LPPG and B13 were detected in only 5-9% cases. In all chronic- phase patients IgG antibodies highly reactive to the three antigens we re present and no significant decrease resulted after benznidazole adm inistration. These observations reinforce previous reports that treatm ent in the acute phase may reduce or eliminate the parasite.