Trypanocidal drugs for chronic asymptomatic Trypanosoma cruzi infection

Trypanocidal drugs for late-stage, symptomatic Chagas disease (Trypanosoma cruzi infection)

BACKGROUND

People with Chagas disease may develop progressive and lethal heart conditions. Drugs to eliminate the parasite Trypanosoma cruzi (T cruzi) currently carry limited therapeutic value and are used in the early stages of the disease. Extending the use of these drugs to treat chronic chagasic cardiomyopathy (CCC) has also been proposed.

OBJECTIVES

To assess the benefits and harms of nitrofurans and trypanocidal drugs for treating late-stage, symptomatic Chagas disease and CCC in terms of blood parasite reduction or clearance, mortality, adverse effects, and quality of life.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and LILACS databases on 12 November 2019. We also searched two clinical trials registers, ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP), on 3 December 2019.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) assessing trypanocidal drugs versus placebo or no treatment for late-stage, symptomatic Chagas disease and CCC.

DATA COLLECTION AND ANALYSIS

We conducted the reporting of the review according the standard Cochrane methods. Two review authors independently retrieved articles, performed data extraction, and assessed risk of bias. Any disagreements were resolved by a third review author. We contacted study authors for additional information.

MAIN RESULTS

We included two studies in this review update. One RCT randomly assigned 26 participants to benznidazole 5 mg/kg/day; 27 participants to nifurtimox 5 mg/kg/day; and 24 participants to placebo for 30 days. The second RCT, newly included in this update, randomised 1431 participants to benznidazole 300 mg/day for 40 to 80 days and 1423 participants to placebo. We also identified one ongoing study. Benznidazole compared to placebo At five-year follow-up, low quality of the evidence suggests that there may be a benefit of benznidazole when compared to placebo for clearance or reduction of antibody titres (risk ratio (RR) 1.25, 95% confidence interval (CI) 1.14 to 1.37; 1 trial; 1896 participants). We are uncertain about the effects of benznidazole for the clearance of parasitaemia demonstrated by negative xenodiagnosis, blood culture, and/or molecular assays due to very limited evidence. Low quality of the evidence suggests that when compared to placebo, benznidazole may make little to no difference in the risk of heart failure (RR 0.89, 95% CI 0.69 to 1.14; 1 trial; 2854 participants) and ventricular tachycardia (RR 0.80, 95% CI 0.51 to 1.26; 1 trial; 2854 participants). We found moderate quality of the evidence that adverse events increase with benznidazole when compared to placebo (RR 2.52, 95% CI 2.09 to 3.03; 1 trial; 2854 participants). Adverse effects were observed in 23.9% of patients in the benznidazole group compared to 9.5% in the placebo group. The most frequent adverse effects were: cutaneous rash, gastrointestinal symptoms, and peripheral polyneuropathy. No data were available for the outcomes of pathological demonstration of tissue parasites and quality of life. Nifurtimox compared to placebo Data were only available for this comparison for the outcome clearance or reduction of antibody titres, and we are uncertain about the effect due to very limited evidence. Regarding adverse events, one RCT mentioned in a general manner that nifurtimox caused intense adverse events, without any quantification.

AUTHORS' CONCLUSIONS

There is insufficient evidence to support the efficacy of the trypanocidal drugs benznidazole and nifurtimox for late-stage, symptomatic Chagas disease and CCC.

Usefulness of real-time PCR during follow-up of patients treated with Benznidazole for chronic Chagas disease: Experience in two referral centers in Barcelona

BACKGROUND

Antitrypanosomal treatment with Benznidazole (BZ) or Nifurtimox may be recommended for patients with chronic Chagas disease (CD) to reduce the onset or progression of symptoms. However, such treatment has limited efficacy and high level of toxic effects. In addition, the current cure biomarker (serology conversion) precludes any treatment assessment unless a prolonged follow-up is arranged. PCR is thus the most useful, alternative surrogate marker for evaluating responses to treatment. The aim of this study is to describe the usefulness of real-time PCR in monitoring BZ treatment within a large cohort of chronic CD cases in Barcelona.

METHODOLOGY/PRINCIPAL FINDINGS

A total of 370 chronic CD patients were monitored with real-time PCR post-BZ treatment. The median follow-up was 4 years (IQR 2.2-5.3y), with a median of 3 clinical visits (IQR 2-4). Only 8 patients (2.2%) presented with at least one incident of positive real-time PCR after treatment and were therefore considered as treatment failure. Four of those failure patients had completed full course treatment, whereas the remaining cases had defaulted with a statistical difference between both groups (p = 0.02). Half of the failure patients had undergone less than 4 years of follow-up monitoring all presented with parasitemia before treatment.

CONCLUSIONS/SIGNIFICANCE

BZ treatment failure was highly infrequent in our cohort. BZ discontinuation was a risk factor for positive real-time PCR results during clinical follow-up. Regular testing with real-time PCR during follow-up allows for early detection of treatment failure in patients with chronic CD.

Structure-Based Virtual Screening and In Vitro Evaluation of New Trypanosoma cruzi Cruzain Inhibitors

Chagas disease (CD), or American trypanosomiasis, causes more than 10,000 deaths per year in the Americas. Current medical therapy for CD has low efficacy in the chronic phase of the disease and serious adverse effects; therefore, it is necessary to search for new pharmacological treatments. In this work, the ZINC¹⁵ database was filtered using the N-acylhydrazone moiety and a subsequent structure-based virtual screening was performed using the cruzain enzyme of Trypanosoma cruzi to predict new potential cruzain inhibitors. After a rational selection process, four compounds, Z2 (ZINC9873043), Z3 (ZINC9870651), Z5 (ZINC9715287), and Z6 (ZINC9861447), were chosen to evaluate their in vitro trypanocidal activity and enzyme inhibition. Compound Z5 showed the best trypanocidal activity against epimatigote (IC₅₀ = 36.26 ± 9.9 μM) and trypomastigote (IC₅₀ = 166.21 ± 14.5 μM and 185.1 ± 8.5 μM on NINOA and INC-5 strains, respectively) forms of Trypanosoma cruzi. In addition, Z5 showed a better inhibitory effect on Trypanosoma cruzi proteases than S1 (STK552090, 8-chloro-N-(3-morpholinopropyl)-5H-pyrimido[5,4-b]-indol-4-amine), a known cruzain inhibitor. This study encourages the use of computational tools for the rational search for trypanocidal drugs.

Chronic Chagas cardiomyopathy: a review of the main pathogenic mechanisms and the efficacy of aetiological treatment following the BENznidazole Evaluation for Interrupting Trypanosomiasis (BENEFIT) trial

Chagas cardiomyopathy is the most frequent and most severe manifestation of chronic Chagas disease, and is one of the leading causes of morbidity and death in Latin America. Although the pathogenesis of Chagas cardiomyopathy is incompletely understood, it may involve several mechanisms, including parasite-dependent myocardial damage, immune-mediated myocardial injury (induced by the parasite itself and by self-antigens), and microvascular and neurogenic disturbances. In the past three decades, a consensus has emerged that parasite persistence is crucial to the development and progression of Chagas cardiomyopathy. In this context, antiparasitic treatment in the chronic phase of Chagas disease could prevent complications related to the disease. However, according to the results of the BENEFIT trial, benznidazole seems to have no benefit for arresting disease progression in patients with chronic Chagas cardiomyopathy. In this review, we give an update on the main pathogenic mechanisms of Chagas disease, and re-examine and discuss the results of the BENEFIT trial, together with its limitations and implications.

Pharmacological interventions for treating heart failure in patients with Chagas cardiomyopathy

BACKGROUND

Chagas disease-related cardiomyopathy is a major cause of morbidity and mortality in Latin America. Despite the substantial burden to the healthcare system, there is uncertainty regarding the efficacy and safety of pharmacological interventions for treating heart failure in people with Chagas disease. This is an update of a Cochrane review published in 2012.

OBJECTIVES

To assess the clinical benefits and harms of current pharmacological interventions for treating heart failure in people with Chagas cardiomyopathy.

SEARCH METHODS

We updated the searches in the Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library 2016, Issue 1), MEDLINE (Ovid; 1946 to to February Week 1 2016), EMBASE (Ovid; 1947 to 2016 Week 07), LILACS (1982 to 15 February 2016), and Web of Science (Thomson Reuters; 1970 to 15 February 2016). We checked the reference lists of included papers. We applied no language restrictions.

SELECTION CRITERIA

We included randomised clinical trials (RCTs) that assessed the effects of pharmacological interventions to treat heart failure in adult patients (18 years or older) with symptomatic heart failure (New York Heart Association classes II to IV), regardless of the left ventricular ejection fraction stage (reduced or preserved), with Chagas cardiomyopathy. We did not apply limits to the length of follow-up. Primary outcomes were all-cause mortality, cardiovascular mortality at 30 days, time-to-heart decompensation, disease-free period (at 30, 60, and 90 days), and adverse events.

DATA COLLECTION AND ANALYSIS

Two authors independently performed study selection, 'Risk of bias' assessment and data extraction. We estimated relative risk (RR) and 95% confidence intervals (CIs) for dichotomous outcomes. We measured statistical heterogeneity using the I² statistic. We used a fixed-effect model to synthesize the findings. We contacted authors for additional data. We developed 'Summary of findings' (SoF) tables and used GRADE methodology to assess the quality of the evidence.

MAIN RESULTS

In this update, we identified one new trial. Therefore, this version includes three trials (108 participants). Two trials compared carvedilol against placebo and another assessed rosuvastatin versus placebo. All trials had a high risk of bias.Meta-analysis of two trials showed a lower proportion of all-cause mortality in the carvedilol groups compared with the placebo groups (RR 0.69; 95% CI 0.12 to 3.88, I² = 0%; 69 participants; very low-quality evidence). Neither of the trials reported on cardiovascular mortality, time-to-heart decompensation, or disease-free periods.One trial (30 participants) found no difference in hospital readmissions (RR 1.00; 95% CI 0.31 to 3.28; very low-quality of evidence) or reported adverse events (RR 0.92; 95% CI 0.67 to 1.27; very low-quality of evidence) between the carvedilol and placebo groups.There was very low-quality evidence from two trials of inconclusive effects on quality of life (QoL) between the carvedilol and placebo groups. One trial (30 participants) assessed QoL with the Minnesota Living With Heart Failure Questionnaire (21 items; item scores range from 0 to 5; a lower MLHFQ score is better). The MD was -14.74; 95% CI -24.75 to -4.73. The other trial (39 participants) measured QoL with the Medical Outcomes Study 36-item short-form health survey (SF-36; item scores range from 0 to 100; higher SF-36 score is better). Data were not provided.One trial (39 participants) assessed the effect of rosuvastatin versus placebo. The trial did not report on any primary outcomes or adverse events. There was very low-quality evidence of uncertain effects on QoL (no data were provided).

AUTHORS' CONCLUSIONS

This first update of our review found very low-quality evidence for the effects of either carvedilol or rosuvastatin, compared with placebo, for treating heart failure in people with Chagas disease. The three included trials were underpowered and had a high risk of bias. There were no conclusive data to support or reject the use of either carvedilol or rosuvastatin for treating Chagas cardiomyopathy. Unless randomised clinical trials provide evidence of a treatment effect, and the trade-off between potential benefits and harms is established, policy-makers, clinicians, and academics should be cautious when recommending or administering either carvedilol or rosuvastatin to treat heart failure in people with Chagas disease. The efficacy and safety of other pharmacological interventions for treating heart failure in people with Chagas disease remains unknown.

A clinical adverse drug reaction prediction model for patients with chagas disease treated with benznidazole

Benznidazole (BZN) is the main trypanocidal drug used to treat Chagas disease, and the evidence supporting the benefits of BZN use during the chronic phase of the disease will favor its use in millions of individuals. However, more than 30% of patients treated with BZN may suffer adverse drug reactions (ADRs), and the development of tools to identify those patients at risk is highly desirable. In the present study, we aimed to identify predictive factors for ADRs in Chagas disease patients treated with BZN. Among 195 patients included in the study, 48.7% experienced ADRs and 31.3% had ADRs that caused BZN treatment discontinuation. Overall ADRs and ADRs that caused BZN treatment discontinuation were more common among women and in those who graduated from elementary school. Overall ADRs were also less frequent among black individuals. Based on logistic regression analysis, female sex (odds ratio [OR], 2.9; 95% confidence interval [CI], 1.5 to 5.4), graduation from elementary school (OR, 2.0; 95% CI, 1.1 to 3.8), and white (OR, 5.0; 95% CI, 1.0 to 24.1) and mulatto (OR, 5.6; 95% CI, 1.1 to 28.7) races were considered to predict overall ADRs, and female sex (OR, 2.3; 95% CI, 1.2 to 4.3) was considered to predict ADRs that caused BZN treatment discontinuation. Graduation from elementary school also presented a tendency to predict ADRs that caused BZN treatment discontinuation (OR, 1.8; 95% CI, 0.9 to 3.6). The logistic regression (LR) models to predict ADRs to BZN described in this study may become important tools to minimize ADRs and improve patients' compliance and thus assist physicians treating patients with Chagas disease with BZN.

Trypanocidal drugs for chronic asymptomatic Trypanosoma cruzi infection

BACKGROUND

Prevention of chronic chagasic cardiomyopathy (CCC) by treating infected populations with trypanocidal therapy (TT) remains a challenge. Despite a renewed enthusiasm for TT, uncertainty regarding its efficacy, concerns about its safety and limited availability remain barriers for a wider use of conventional drugs. We have updated a previous version of this review.

OBJECTIVES

To systematically search, appraise, identify and extract data from eligible studies comparing the outcome of cohorts of seropositive individuals to Trypanosoma cruzi exposed to TT versus placebo or no treatment.

SEARCH METHODS

We sought eligible studies in electronic databases (Cochrane Central Register of Controlled Trials (CENTRAL), Issue 1, 2014); MEDLINE (Ovid, 1946 to January week 5 2014); EMBASE (Ovid, 1980 to 2014 week 6) and LILACS (up to 6 May 2010)) by combining terms related with the disease and the treatment. The search also included a Google search, handsearch for references in review or selected articles, and search of expert files. We applied no language restrictions.

SELECTION CRITERIA

Review authors screened the retrieved references for eligibility (those dealing with human participants treated with TT) and then assessed the pre-selected studies in full for inclusion. We included randomised controlled trials (RCTs) and observational studies that provided data on either mortality or clinical progression of CCC after at least four years of follow-up.

DATA COLLECTION AND ANALYSIS

Teams of two review authors independently carried out the study selection, data extraction and risk of bias assessment, with a referee resolving disagreement within the pairs. Data collection included study design, characteristics of the population and interventions or exposures and outcome measures. We defined categories of outcome data as parasite-related (positive serology, xenodiagnosis or polymerase chain reaction (PCR) after TT) and participant-related (including efficacy outcomes such as progression towards CCC, all-cause mortality and side effects of TT). We reported pooled outcome data as Mantel-Haenszel odds ratios (OR) or standardised mean differences (SMD) along with 95% confidence intervals (CI), using a random-effects model. I(2) statistics provided an estimate of heterogeneity across studies. We conducted an exploratory meta-regression analysis of the relationship between positive-serology and progression of CCC or mortality.

MAIN RESULTS

We included 13 studies involving 4229 participants (six RCTs, n = 1096, five RCTs of intermediate risk of bias, one RCT of high risk of bias; four non-randomised experiments, n = 1639 and three observational studies, n = 1494). Ten studies tested nitroderivative drugs nifurtimox or benznidazole (three exposed participants to allopurinol, one to itraconazole). Five studies were conducted in Brazil, five in Argentina, one in Bolivia, one in Chile and one in Venezuela.TT was associated with substantial, but heterogeneous reductions on parasite-related outcomes such as positive serology (9 studies, OR 0.21, 95% CI 0.10 to 0.44, I(2) = 76%), positive PCR (2 studies, OR 0.50, 95% CI 0.27 to 0.92, I(2) = 0%), positive xenodiagnosis after treatment (6 studies, OR 0.35, 95% CI 0.14 to 0.86, I(2) = 79%), or reduction on antibody titres (3 studies, SMD -0.56, 95% CI -0.89 to -0.23, I(2) = 28%). Efficacy data on patient-related outcomes was largely from non-RCTs. TT with nitroderivatives was associated with potentially important, but imprecise and inconsistent reductions in progression of CCC (4 studies, 106 events, OR 0.74, 95% CI 0.32 to 1.73, I(2) = 66%) and mortality after TT (6 studies, 99 events, OR 0.55, 95% CI 0.26 to 1.14, I(2) = 48%). The overall median incidence of any severe side effects among 1475 individuals from five studies exposed to TT was 2.7%, and the overall discontinuation of this two-month therapy in RCTs (5 studies, 134 events) was 20.5% (versus 4.3% among controls) and 10.4% in other five studies (125 events).

AUTHORS' CONCLUSIONS

Despite the evidence that TT reduced parasite-related outcomes, the low quality and inconsistency of the data for patient-important outcomes must be treated with caution. More geographically diverse RCTs testing newer forms of TT are warranted in order to 1. estimate efficacy more precisely, 2. explore factors potentially responsible for the heterogeneity of results and 3. increase knowledge on the efficacy/tolerance balance of conventional TT.

American trypanosomiasis

American trypanosomiasis is a parasitic disease caused by the flagellate protozoan Trypanosoma cruzi. Chagas disease is endemic in Latin America, where an estimated 10-14 million people are infected, and an emerging disease in Europe and the USA. Trypanosoma cruzi is transmitted by blood-sucking bugs of the family Reduviidae. Rhodnius prolixus, Panstrongylus megistus, Triatoma infestans, and T. dimidiata are the main vectors in the sylvatic cycle. Non vector-borne transmission includes blood transfusion, congenital and oral transmission, transplantation, and accidental infections. Most cases of acute infection occur in childhood and are usually asymptomatic, although severe myocarditis and meningoencephalitis may occur. Approximately 30% of T. cruzi-infected people will develop the chronic stage of the disease. Chronic chagasic cardiomyopathy is characterized by progressive heart failure, arrhythmias, intraventricular conduction defects, sudden death, and peripheral thromboembolism. Acute exacerbation can occur in individuals with involvement of cellular immunity such as advanced AIDS (acquired immunodeficiency syndrome), and transplant-associated immunosuppression. Neurological involvement may present with encephalitis, meningoencephalitis, or a space-occupying cerebral lesion called chagoma. Chagas disease is a major cause of ischemic stroke in Latin America. Several epidemiological studies have found an association between T. cruzi infection and cardioembolic ischemic stroke. Benznidazole and nifurtimox are the two available trypanocide drugs against T. cruzi.

Pharmacological interventions for treating heart failure in patients with chagas cardiomyopathy

BACKGROUND

Chagas disease-related cardiomyopathy is a major cause of morbidity and mortality in Latin America. Despite the substantial burden to the healthcare system, there is uncertainty regarding the efficacy and safety of pharmacological interventions for treating heart failure in patients with Chagas disease.

OBJECTIVES

To assess the benefits and harms of current pharmacological interventions for treating heart failure in patients with Chagas cardiomyopathy.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library) Issue 1, 2011, MEDLINE (Ovid), EMBASE (Ovid), LILACS and ISI Web of Science to April 2011. We checked the reference lists of included papers. No language restrictions were applied.

SELECTION CRITERIA

We included randomized clinical trials assessing the effects of pharmacological interventions for treating heart failure in adult patients (≥18 years) with symptomatic heart failure (New York Heart Association class II to IV), irrespective of the left ventricular ejection fraction stage, reduced or preserved, with Chagas cardiomyopathy. No limits were applied with respect to the follow-up duration. Primary outcomes were all-cause mortality, cardiovascular mortality at 30 days, time to heart decompensation and disease-free period (at 30, 60 and 90 days), and adverse events.

DATA COLLECTION AND ANALYSIS

Two authors independently performed study selection, risk of bias assessment and data extraction. We estimated relative risks (RR) and the respective 95% confidence intervals (CIs) for dichotomous outcomes. We measured statistical heterogeneity using the I(2) statistic. We used a fixed-effect model to synthesize the findings. We contacted authors for additional data.

MAIN RESULTS

We included two randomized clinical trials involving 69 participants. Both trials compared carvedilol against placebo, and had a high risk of bias. Carvedilol compared with placebo did not significantly affect all-cause mortality (2/34 (5.88%) versus 3/35 (5.87%); pooled RR 0.69, 95% CI 0.12 to 3.88, I(2) = 0%). None of the trials reported on cardiovascular mortality, time to heart decompensation or disease-free period. Evidence on the adverse effects of carvedilol is inconclusive.

AUTHORS' CONCLUSIONS

This Cochrane review has found a lack of evidence on the effects of carvedilol for treating heart failure in patients with Chagas disease. The two included trials were underpowered and had a high risk of bias. There are no conclusive data to support the use of carvedilol for treating Chagas cardiomyopathy. Unless randomized clinical trials provide evidence of a treatment effect, and the trade off between potential benefits and harms is established, policy-makers, clinicians, and academics should be cautious when recommending and administering carvedilol for treating heart failure in patients with Chagas disease. The efficacy and safety of other pharmacological interventions for treating heart failure in patients with Chagas disease is unknown.

Trypanosoma cruzi infection: a review with emphasis on cutaneous manifestations

Chagas disease, an infection caused by the protozoan Trypanosoma cruzi and transmitted by the Reduuvid insect vector, remains a major cause of morbidity in Central and South America over a century after its discovery in 1909. Though major advances in preventing the spread of this disease have been made in recent decades, millions of individuals remain chronically infected due to prior exposure to T. cruzi and are at risk for future complications from the disease. Dermatologic manifestations of acute infection may include localized swelling at the site of inoculation (chagoma), conjunctivitis (Romaña's sign), and a generalized morbilliform eruption (schizotrypanides). Reactivation of quiescent infection in immunocompromised hosts due to the acquired immunodeficiency syndrome or organ transplantation can present with fever and skin lesions including panniculitis. The widespread emigration of chronic carriers of T. cruzi to North America, Europe, and Australia makes it imperative that dermatologists worldwide be familiar with this entity to ensure proper diagnosis and treatment.

American trypanosomiasis (Chagas disease)

Chagas disease, also known as American trypanosomiasis, is a chronic infection caused by Trypanosoma cruzi, a protozoan parasite. It is transmitted to human beings mainly through the feces of infected triatomine bugs. The disease affects an estimated 8 to 10 million people in the Americas, putting them at risk of developing life-threatening cardiac and gastrointestinal complications. This article provides a brief update on the epidemiology, clinical manifestations, diagnosis, and treatment of Chagas disease.

Therapy of chagas disease: implications for levels of prevention

This paper reviews the evidence supporting the use of etiological treatment for Chagas disease that has changed the standard of care for patients with Trypanosoma cruzi infection in the last decades. Implications of this evidence on different levels of prevention as well as gaps in current knowledge are also discussed. In this regard, etiological treatment has shown to be beneficial as an intervention for secondary prevention to successfully cure the infection or to delay, reduce, or prevent the progression to disease, and as primary disease prevention by breaking the chain of transmission. Timely diagnosis during initial stages would allow for the prescription of appropriate therapies mainly in the primary health care system thus improving chances for a better quality of life. Based on current evidence, etiological treatment has to be considered as an essential public health strategy useful to reduce disease burden and to eliminate Chagas disease altogether.

Chagas disease: changes in knowledge and management

More than 100 years after the discovery of human American trypanosomiasis by Carlos Chagas, our knowledge and management of the disease are profoundly changing. Substantial progress made by disease control programmes in most endemic areas contrasts with persisting difficulties in the Gran Chaco region in South America and the recent emergence of the disease in non-endemic areas because of population movements. In terms of pathogenesis, major discoveries have been made about the life cycle and genomics of Trypanosoma cruzi, and the role of the parasite itself in the chronic phase of the disease. From a clinical perspective, a growing number of arguments have challenged the notion of an indeterminate phase, and suggest new approaches to manage patients. New methods such as standardised PCR will be necessary to ensure follow-up of this chronic infection. Although drugs for treatment of Chagas disease are limited, poorly tolerated, and not very effective, treatment indications are expanding. The results of the Benznidazole Evaluation For Interrupting Trypanosomiasis (BENEFIT) trial in 2012 will also help to inform treatment. Mobilisation of financial resources to fund research on diagnosis and randomised controlled trials of treatment are international health priorities.

Comparative effectiveness of medical interventions in adults versus children

OBJECTIVE

To estimate the comparative effectiveness of medical interventions in adults versus children.

STUDY DESIGN

We identified from the Cochrane Database of Systematic Reviews (Issue 1, 2007) meta-analyses with data on at least 1 adult and 1 pediatric randomized trial with binary primary efficacy outcome. For each meta-analysis, we calculated the summary odds ratio of the adult trials and the pediatric trials, respectively; the relative odds ratio (ROR) of the adult versus pediatric odds ratios per meta-analysis; and the summary ROR across all meta-analyses. ROR <1 means that the experimental intervention is more unfavorable in children than adults.

RESULTS

Across 128 eligible meta-analyses (1051 adult and 343 pediatric trials), the summary ROR did not show a statistically significant difference between adults and children (0.96; 95% confidence intervals, 0.86 to 1.08). However, in all meta-analyses except for 1, the individual ROR's 95% confidence intervals could not exclude a relative difference in efficacy over 20%. In two-thirds, the relative difference in observed point estimates exceeded 50%. Nine statistically significant discrepancies were identified; 4 of them were also clinically important.

CONCLUSIONS

Treatment effects are on average similar in adults and children, but available evidence leaves large uncertainty about their relative efficacy. Clinically important discrepancies may occur.

Image-based high-throughput drug screening targeting the intracellular stage of Trypanosoma cruzi, the agent of Chagas' disease

Chagas' disease, caused by infection with the parasite Trypanosoma cruzi, is the major cause of heart failure in Latin America. Classic clinical manifestations result from the infection of heart muscle cells leading to progressive cardiomyopathy. To ameliorate disease, chemotherapy must eradicate the parasite. Current drugs are ineffective and toxic, and new therapy is a critical need. To expedite drug screening for this neglected disease, we have developed and validated a cell-based, high-throughput assay that can be used with a variety of untransfected T. cruzi isolates and host cells and that simultaneously measures efficacy against the intracellular amastigote stage and toxicity to host cells. T. cruzi-infected muscle cells were incubated in 96-well plates with test compounds. Assay plates were automatically imaged and analyzed based on size differences between the DAPI (4',6-diamidino-2-phenylindole)-stained host cell nuclei and parasite kinetoplasts. A reduction in the ratio of T. cruzi per host cell provided a quantitative measure of parasite growth inhibition, while a decrease in count of the host nuclei indicated compound toxicity. The assay was used to screen a library of clinically approved drugs and identified 55 compounds with activity against T. cruzi. The flexible assay design allows the use of various parasite strains, including clinical isolates with different biological characteristics (e.g., tissue tropism and drug sensitivity), and a broad range of host cells and may even be adapted to screen for inhibitors against other intracellular pathogens. This high-throughput assay will have an important impact in antiparasitic drug discovery.

Chagas disease and stroke

Chagas disease is a neglected infectious disease in the tropics and an emerging health problem in Europe and the USA. In the past decade, a link has been recorded between ischaemic stroke and Trypanosoma cruzi infection in several epidemiological studies, and an increase in stroke prevalence is expected with the ageing of the population infected with T cruzi in Latin America. Heart failure, mural thrombus, left ventricular apical aneurysm, and several types of cardiac arrhythmias are associated with stroke in Chagas disease. Stroke could also be the first sign of Chagas disease in asymptomatic patients and those with mild systolic dysfunction, so patients with stroke who are from endemic regions should be screened for T cruzi infection. The most frequent stroke syndrome seen in patients with Chagas disease is partial anterior circulation infarction. Stroke recurrence has been estimated to occur in 20% of patients, and secondary prevention measures include chronic anticoagulation in cardioembolic chagasic stroke. So far, no studies have been done to assess the effect of chagasic stroke on vascular dementia.

Stroke: a neglected complication of American trypanosomiasis (Chagas’ disease)

American trypanosomiasis, also known as Chagas' disease (CD), is a major public health problem and a frequent cause of chronic cardiomyopathy and stroke in South America. The role of CD as an independent stroke risk factor is reviewed. Chronic cardiomyopathy can appear 10-30 years after the initial infection and affects about 30% of CD patients. Cardiac arrhythmias, congestive heart failure, apical aneurysm and mural thrombus are potential embolic factors that partially explain the genesis of chagasic stroke. Prevalence of apical aneurysm and mural thrombus in CD stroke patients has been estimated in 37 and 11.7%, respectively. Nevertheless, not all stroke chagasic patients have a severe myocardiopathy. Stroke may also be the first manifestation of CD in patients with mild or undetected systolic dysfunction. The diagnosis of CD may be established after stroke presentation in around 40% of patients. Awareness of stroke risk in chagasic patients is very poor and has been estimated in less than 5%. Chagasic cardiomyopathy is a neglected, frequently unrecognized, source of cardioembolic stroke in South America. Educational and prevention programs should be performed in order to prevent this complication of the chronic form of CD.

Neglected diseases, civil conflicts, and the right to health

Neglected diseases remain one of the largest causes of disease and mortality. In addition to the difficulties in provision of appropriate drugs for specific diseases, many other factors contribute to the prevalence of such diseases and the difficulties in reducing their burden. We address the role that poor governance and politically motivated oppression have on the epidemiology of neglected diseases. We give case examples including filariasis in eastern Burma and vector-borne diseases (Chagas' disease, leishmaniasis, and yellow fever) in Colombia, we show the links between systematic human rights violations and the effects of infectious disease on health. We also discuss the role of researchers in advocating for and researching within oppressed populations.

Clinical aspects of the Chagas' heart disease

Chagas' heart disease, caused by protozoan Trypanosoma cruzi, is a common cause of cardiomyopathy in the Americas. Transmission of T. cruzi occurs through Reduviids, the kissing bugs. Less common ways of transmission are blood transfusion, congenital transmission, organ transplantation, laboratory accident, breastfeeding, and oral contamination. Infestation results in cardiac dysautonomia, myocardial apoptosis, and myocardial fibrosis. In acute phase, death is mostly caused by myocarditis and in chronic phase, it is mostly by irreversible cardiomyopathy. A majority of the patients with Chagas' disease remain in the latent phase of disease for 10 to 30 years or even for life. Specific anti-Chagas' therapy with trypanocide drugs is useful in acute phase but the management of chronic Chagas' heart disease is mostly empirical. The mortality during the acute phase of cardiac Chagas is around 5%. Five-year mortality of chronic Chagas' disease with cardiac dysfunction is above 50%. The clinical aspects of the Chagas' heart disease are concisely reviewed.

Trypanocidal drugs for late stage, symptomatic Chagas disease (Trypanosoma cruzi infection)

BACKGROUND

People with Chagas disease (American Trypanosomiasis) may develop progressive and potentially lethal heart conditions. Drugs to eliminate the causative parasite, Trypanosoma cruzi, currently in use have limited therapeutic value and are used in early stages of the disease. Extending the use of these drugs to treat symptomatic chronic parasitism with chronic Chagasic cardiopathy (CCC) and progressive dilated cardiomyopathy has been proposed.

OBJECTIVES

To assess the effects (harms and benefits) of nitrofurans and imidazolic trypanocidal drugs for treating late stage chronic Chagas disease and CCC.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library (Issue 3, 2004), MEDLINE (1985-2004), EMBASE (1985-2004), BIREME (1985-2004), LILACS (1985-2004), ARTEMISA (1985-2004), SCIELO (1985-2004). Indexing terms in English and Spanish were used. References obtained were assessed for relevance by two reviewers independently.

SELECTION CRITERIA

We included randomized controlled clinical trials (RCTs), single or double blind using trypanocidal drugs versus placebo or no treatment in CCC.

DATA COLLECTION AND ANALYSIS

All articles retrieved were assessed using a predefined check list to determine if they met the inclusion criteria. Two independent reviewers collected data using a pre-designed form piloted on three articles before the review process started. Disagreements were resolved by a third reviewer. If the information was unavailable the articles were excluded. We planned a quantitative analysis of reduction of parasite load whether recorded as a categorical variable or the reduction of specific antibody titers. However insufficient data were available for quantitative analysis. We prepared a qualitative description of data identified.

MAIN RESULTS

We found only one randomized double blind placebo controlled trial. We also found six uncontrolled or non-randomized studies which were of some relevance and were therefore described. We found insufficient evidence to define the effects of drug treatment for people with CCC.

AUTHORS' CONCLUSIONS

There is insufficient evidence to support the efficacy of nitrofurans or imidazolic drugs as recommended treatment in CCC and chronic T.cruzi infections, specifically if overt heart disease is present. A well designed randomized controlled trial is necessary to establish if new drugs are suitable for treatment of cardiac patients with CCC.

Changing Epidemiology and Approaches to Therapy for Chagas Disease

Impressive progress has been made in reducing the incidence of Chagas disease, or American trypanosomiasis, in many countries in which the illness is endemic. This has been achieved through expanded blood screening programs and low-technology vector control. Despite the progress made in reducing the number of new cases, the burden of disability and mortality in the endemic countries is enormous and will continue to be so for many years since a substantial portion of the 16 to 18 million persons already infected will develop chronic symptomatic Chagas disease. Unfortunately, no progress has been made in developing new drugs for Trypanosoma cruzi infection, and nifurtimox and benznidazole, both of which lack efficacy and often cause severe side effects, remain the only options for treatment.