The efficacy of treatment with nifurtimox and/or benznidazole among adults with chronic Chagas disease with no previous electrocardiographic disturbances was evaluated over a mean follow-up of 21 years, by means of conventional serology, xenodiagnosis, clinical examination, electrocardiograms and chest X-ray. One hundred and eleven patients, between 17 and 46 years old, were studied: 54 underwent treatment (nifurtimox 27, benznidazole 27) and 57 remained untreated (control group). Xenodiagnosis was performed on 65% of them: 36/38 of the treated and 9/34 of the untreated patients had previous positive xenodiagnosis. Post-treatment, 133 xenodiagnoses were performed on 41 patients, all resulting negative. In the control group, 29 xenodiagnoses were performed on 14 patients; 2 resulted positive. Sera stored during the follow-up were simultaneously analyzed through conventional serology tests (IHA; DA-2ME; IIF). The serological evolution in the treated group was: a) 37% underwent negative seroconversion (nifurtimox 11, benznidazole 9); b) 27.8% decreased titers (nifurtimox 9, benznidazole 6), 9 showed inconclusive final serology (nifurtimox 7, benznidazole 2); c) 35.2% remained positive with constant titers (nifurtimox 7; benznidazole 12). The control group conserved the initial antibody levels during the follow-up. In the clinical evolution, 2/54 (3.7%) of the treated and 9/57 (15.8%) of the untreated patients showed electrocardiographic disturbances attributable to Chagas myocardiopathy, with a statistically relevant difference (p<0.05). Treatment caused deparasitation in at least 37% of the chronically infected adults and a protective effect on their clinical evolution.

SUMMARYThis work compared the time at which negative seroconversion was detected by conventional serology (CS) and by the ELISA-F29 test on a cohort of chronic chagasic patients treated with nifurtimox or benznidazole. A retrospective study was performed using preserved serum from 66 asymptomatic chagasic adults under clinical supervision, and bi-annual serological examinations over a mean follow-up of 23 years. Twenty nine patients received trypanocide treatment and 37 remained untreated. The ELISA-F29 test used a recombinant antigen which was obtained by expressing the Trypanosoma cruzi flagellar calcium-binding protein gene in Escherichia coli. Among the untreated patients, 36 maintained CS titers. One patient showed a doubtful serology in some check-ups. ELISA-F29 showed constant reactivity in 35 out of 37 patients and was negative for the patient with fluctuating CS. The treated patients were divided into three groups according to the CS titers: in 13 they became negative; in 12 they decreased and in four they remained unchanged. ELISA-F29 was negative for the first two groups. The time at which negativization was detected was significantly lower for the ELISA-F29 test than for CS, 14.5 ± 5.7 and 22 ± 4.9 years respectively. Negative seroconversion was observed in treated patients only. The results obtained confirm that the ELISA-F29 test is useful as an early indicator of negative seroconversion in treated chronic patients.

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Los anticuerpos anti-muscarínicos (anti-M2) podrían estar relacionados con alteraciones disautonómicas en la enfermedad de Chagas. Objetivo: evaluar efecto del tratamiento tripanocida sobre los anticuerpos anti-M2 en adultos chagásicos crónicos seguidos durante 24 años promedio. Estudio de cohorte retrospectivo. Infectados crónicos por T. cruzi agrupados en: A) 31 tratados con drogas tripanocidas (102 muestras post-tratamiento); B) 36 no tratados (95 muestras). Controles no chagásicos: 17 cardiópatas y 22 sanos. Pacientes tratados: 11/31(35,5%) inicialmente presentaron reactividad anti-M2; 2/31(6,4%) permanecieron reactivos durante el estudio. No tratados: 14/36(38,9%) fueron positivos al inicio y final del seguimiento. Todos los pacientes permanecieron sin cambio clínicos durante el estudio. Los controles no presentaron reactividad anti-M2. El origen de los anticuerpos anti-M2 no sería de naturaleza autoinmune ya que desaparecen por efecto del tratamiento tripanocida y por otro lado la presencia de los mismos no tendría utilidad como marcador pronóstico de evolución clínica. Palabras claves: Enfermedad de Chagas-Tratamiento tripanocida-Anticuerpos antimuscarínicos SUMMARY Chronic Chagas Disease: effect of trypanocidal treatment on antimuscarinic antibodies Anti-muscarinic antibodies (anti-M2) could be related to dysautonomic alterations in Chagas disease. Objective: evaluate effect of trypanocidal treatment on the anti-M2 antibodies in chronic chagasic adults followed for 24 years on average. Retrospective cohort study. Chronic patients infected by T. cruzi were grouped into: A)31 treated with trypanocidal drugs (102 samples post-treatment); B)36 untreated (95 samples). Controls no chagasic: 17 with cardiopathies and 22 healthy. Patients treated: 11/31(35.5%) initially presented anti-M2 reactivity; 2/31 during the study remained reactive. Untreated: 14/36(38.9%) were positive at the beginning and to the end of follow up. All patients remained without clinical change during the study. The controls no showed anti-M2 reactivity. The origin of anti-M2 antibodies would not be autoimmune as they disappear by effect of trypanocidal treatment and on the other hand the presence of them would not be useful as a prognostic marker of clinical evolution.