Compared with no treatment, benznidazole treatment was associated with reduced progression of Chagas disease and increased negative seroconversion for patients presenting with nonacute disease and no heart failure. These observations indicate that a randomized, controlled trial should now be conducted.

Chagas disease is caused by a parasite, Trypanosoma cruzi, transmitted primarily by a triatomine insect and affects approximately 8 million people in Latin American countries. The principal aim of the management of the disease is to avoid the development of cardiomyopathy and transmission by blood transfusion, congenital and organ transplants. Currently, benznidazole is the only etiological treatment commercially available for the disease until new and better drugs can be developed and tested. Benznidazole has been used even though it does not have all the conditions of an ideal drug. The efficacy and tolerance of benznidazole is inversely related to the age of the patient, while its side effects are more frequent in elderly patients. The side effects are systematically evaluated only in controlled studies designed for that purpose. However, the true clinical impact of the side effects could be different, considering that the treatment is for a short duration (between 30 and 60 days) and only carried out once. In this article, we discuss the benefits and risks of the treatment with benznidazole from a clinical point of view to be considered for the management of the treatment of chronic adult Chagas disease patients in the current medical practice.

Background As many as 20 million people are living with Trypanosoma cruzi infection in Latin American, yet few receive any treatment. The major limitation in developing and evaluating potential new drugs for their efficacy is the lack of reliable tests to assess parasite burden and elimination. Methods Adults volunteers with chronic T. cruzi infection were evaluated clinically and stratified according to the Kuschnir classification. Individuals in group 0 and group 1 clinical status were treated with 5 mg benznidazole/kg/day for 30 days. The changes in T. cruzi-specific T cell and antibody responses, as well as in clinical status, were measured periodically over the 3-5 year follow-up period and compared to pre-treatment conditions and to an untreated control group. Results The frequency of peripheral IFN- g-producing T cells specific for T. cruzi declined as early as 12 months after BZ treatment and subsequently became undetectable in a substantial proportion of treated subjects. Addtionally decreases in antibody responses to a pool of recombinant T. cruzi proteins also declined in many of these same subjects. The shift to negative IFN- g T cell responses was highly associated with an early increase in IFN- g-producing T cells with phenotypic features of effector/effector memory cells in a subset of subjects. Benznidazole treatment also resulted in an increase in naïve and early differentiated memory-like CD8+ T cells in a majority of subjects. Conclusions BZ treatment during chronic Chagas disease has a substantial impact on parasite-specific immune response that is likely to be indicative of treatment efficacy and cure.

BackgroundThe main criterion for treatment effectiveness in Chagas Disease has been the seronegative conversion, achieved many years post-treatment. One of the main limitations in evaluating treatment for chronic Chagas disease is the lack of reliable tests to ensure parasite clearance and to examine the effects of treatment. However, declines in conventional serological titers and a new multiplex assay can be useful tools to monitor early the treatment impact.Methodology/Principal FindingsChanges in antibody levels, including seronegative conversion as well as declines in titers, were serially measured in 53 benznidazole-treated and 89 untreated chronic patients in Buenos Aires, Argentina with a median follow-up of 36 months. Decrease of titers (34/53 [64%] treated vs. 19/89 [21%] untreated, p<0.001) and seronegative conversion (21/53, [40%] treated vs. 6/89, [7%] untreated, p<0.001) in at least one conventional serological test were significantly higher in the benznidazole-treated group compare with the untreated group. When not only complete seronegative conversion but also seronegative conversion on 2 tests and the decreases of titers on 2 or 3 tests were considered, the impact of treatment on conventional serology increased from 21% (11/53 subjects) to 45% (24/53 subjects). A strong concordance was found between the combination of conventional serologic tests and multiplex assay (kappa index 0.60) to detect a decrease in antibody levels pos-treatment.Conclusions/SignificanceTreatment with benznidazole in subjects with chronic Chagas disease has a major impact on the serology specific for T. cruzi infection in a shorter follow-up period than previously considered, reflected either by a complete or partial seronegative conversion or by a significant decrease in the levels of T. cruzi antibodies, consistent with a possible elimination or reduction of parasite load.

There is a clinical need to test new schemes of benznidazole administration that are expected to be at least as effective as the current therapeutic scheme but safer. This study assessed a new scheme of benznidazole administration in chronic Chagas disease patients. A pilot study with intermittent doses of benznidazole at 5 mg/kg/day in two daily doses every 5 days for a total of 60 days was designed. The main criterion of response was the comparison of quantitative PCR (qPCR) findings prior to and 1 week after the end of treatment. The safety profile was assessed by the rate of suspensions and severity of adverse effects. Twenty patients were analyzed for safety, while qPCR was tested for 17 of them. The average age was 43 ؎ 7.9 years; 55% were female. Sixty-five percent of treated subjects showed detectable qPCR results prior to treatment of 1.45 (0.63 to 2.81) and 2.1 (1.18 to 2.78) parasitic equivalents per milliliter of blood (par.eq/ml) for kinetoplastic DNA (kDNA) qPCR and nuclear repetitive sequence satellite DNA (SatDNA) qPCR, respectively. One patient showed detectable PCR at the end of treatment (1/17), corresponding to 6% treatment failure, compared with 11/17 (65%) patients pretreatment (P ‫؍‬ 0.01). Adverse effects were present in 10/20 (50%) patients, but in only one case was treatment suspended. Eight patients showed mild adverse effects, whereas moderate reactions with increased liver enzymes were observed in two patients. The main accomplishment of this pilot study is the promising low rate of treatment suspension. Intermittent administration of benznidazole emerges a new potential therapeutic scheme, the efficacy of which should be confirmed by long-term assessment posttreatment.