Trypanosoma cruzi antigens detected by immunoelectron microscopy in the spleen of mice serologically positive but parasitologically cured by chemotherapy. (Preliminary report)

Antibody drop in newborns congenitally infected by Trypanosoma cruzi treated with benznidazole

OBJECTIVE

To compare the drop of Chagas antibody titres between non-infected and congenitally infected newborns treated by two doses of benznidazole, aiming at evaluating the recovery time and giving recommendations regarding serological criteria of recovery.

METHODS

During a clinical trial, the drop of Trypanosoma cruzi antibody titres measured by ELISA tests was followed during the first year of life in congenitally infected newborns treated with different doses of benznidazole and compared to T. cruzi antibody titres in non-parasitaemic newborns. Confirmation of recovery was given by two negative serological tests: Chagas Stat-Pak (CSP) (immunochromatography) and Chagatest v3.0 (ELISA).

RESULTS

In non-parasitaemic infants of infected mothers, antibodies of maternal origin disappeared in <8 months while in infected infants, T. cruzi antibodies decreased more slowly and disappeared in 9-16 months allowing to confirm the recovery. All CSP tests were negative before the ninth month while about 10% of ELISA tests remained positive at the 12th month.

CONCLUSIONS

Recovery may be confirmed in most cases at 10 months. The CSP test was compared to Chagatest v3.0 ELISA and appeared to give a reliable response. The decrease rate of antibodies does not depend on treatment modes.

Treatment of chronic Chagas' disease with benznidazole: clinical and serologic evolution of patients with long-term follow-up

Prescribing etiologic treatment for chronic Chagas' disease is highly controversial because of the difficulties involved in assessing its therapeutic efficacy--the low degree of parasitemia, the persistence of positive immunologic reactions, the lack of clinical findings to support each type of treatment, and the necessarily prolonged follow-up of the patient. An 8-year average follow-up was performed on 131 patients treated with benznidazole (5 mg/kg/day for 30 days) (TP) and 70 untreated patients (UTP) by serial electrocardiograms and analysis of the cardiomyopathic progress of the clinical groups, and by immunologic tests at both the beginning and end of the study. TPs presented less electrocardiographic changes during the follow-up period (4.2% vs 30%) and a lower frequency of deterioration in their clinical condition (2.1% vs 17%). The percentage of TPs who were serologically negative was 19.1% whereas 6% of the UTPs became serologically negative, a result that correlated with a lack of progress in the cardiomyopathy. Benznidazole treatment significantly decreased serologic titers, signifying parasitologic cure in two patients.

Lytic antibody titre as a means of assessing cure after treatment of Chagas disease: a 10 years follow-up study

A complement-mediated lysis test (CoML) using living trypomastigotes was compared with conventional serological methods and with haemoculture. Over a 10 years follow-up period evidence was obtained which supported the view that chagasic patients, treated with nitroheterocyclic drugs, in whom CoML had reverted to negative, might be considered cured despite conventional serology remaining positive.