[Indeterminate form of Chagas disease: considerations about diagnosis and prognosis]

Correlation of blood-based immune molecules with cardiac gene expression profiles reveals insights into Chagas cardiomyopathy pathogenesis

Introduction

Understanding compartmentalized immune responses in target organs is crucial for elucidating the pathogenesis of various diseases. However, obtaining samples from affected vital organs often poses safety challenges. In this study, we aimed to investigate potential correlations between the levels of disease-associated immune molecules in the bloodstream with their gene expression profiles in the hearts of patients suffering from Chagas Cardiomyopathy (CCC). This debilitating and often fatal condition is caused by infection with the protozoan Trypanosoma cruzi.

Methods

Blood samples were analyzed using the Bio-Plex platform. Gene Expression Omnibus (GEO) database was used to determine gene expression profile in heart tissue from CCC and non-Chagas controls (CTRL).

Results

Elevated levels of inflammatory cytokines were detected in the plasma of CCC patients, and these levels correlated with clinical indicators of deteriorating cardiac function. Notably, 75% of the soluble factors assessed in the plasma exhibited a consistent relationship with their gene expression levels in the cardiac tissue of CCC patients. Analysis of interactions and signaling pathways related to these molecules revealed an overrepresentation of inflammatory pathways in both blood and heart compartments. Moreover, we identified that differentially expressed genes in CCC cardiac tissue were primarily associated with T-cell signaling pathways and correlated with the presence of CD8+ T cells in the myocardium.

Discussion

Our findings establish a strong correlation between relevant immune molecules and their signaling pathways in both the blood and heart tissue in CCC. This validates the use of blood as a non-invasive medium for understanding immunopathology and identifying markers for cardiac dysfunction in Chagas disease.

Modulation of Regulatory T Cells Activity by Distinct CD80 and CD86 Interactions With CD28/CTLA-4 in Chagas Cardiomyopathy

Chagas cardiomyopathy is the symptomatic cardiac clinical form (CARD) of the chronic phase of Chagas disease caused by Trypanosoma cruzi infection. It was described as the most fibrosing cardiomyopathies, affecting approximately 30% of patients during the chronic phase. Other less frequent symptomatic clinical forms have also been described. However, most patients who progress to the chronic form develop the indeterminate clinical form (IND), may remain asymptomatic for life, or develop some cardiac damage. Some mechanisms involved in the etiology of the clinical forms of Chagas disease have been investigated. To characterize the contribution of CD80 and CD86 co-stimulatory molecules in the activation of different CD4⁺ (Th1, Th2, Th17, and Treg) and CD8⁺ T lymphocyte subsets, we used blocking antibodies for CD80 and CD86 receptors of peripheral blood mononuclear cells (PBMC) in cultures with T. cruzi antigens from non-infected (NI), IND, and CARD individuals. We demonstrated a higher frequency of CD8⁺ CD25⁺ T lymphocytes and CD8⁺ Treg cells after anti-CD80 antibody blockade only in the CARD group. In contrast, a lower frequency of CD4⁺ Treg lymphocytes after anti-CD86 antibody blockade was found only in IND patients. A higher frequency of CD4⁺ Treg CD28⁺ lymphocytes, as well as an association between CD4⁺ Treg lymphocytes and CD28⁺ expression on CD4⁺ Treg cells in the CARD group, but not in IND patients, and once again only after anti-CD80 antibody blockade, was observed. We proposed that Treg cells from IND patients could be activated via CD86-CTLA-4 interaction, leading to modulation of the immune response only in asymptomatic patients with Chagas disease, while CD80 may be involved in the proliferation control of T CD8⁺ lymphocytes, as also in the modulation of regulatory cell activation via CD28 receptor. For the first time, our data highlight the role of CD80 in modulation of Treg lymphocytes activation in patients with CARD, highlighting a key molecule in the development of Chagas cardiomyopathy.

Determinants of Functional Capacity in Patients with Chagas Disease

BACKGROUND

Chagas disease leads to reduced functional capacity. However, the stage at which functional impairment is detectable remains unclear.

OBJECTIVES

The present study was addressed to compare the functional capacity of patients at different stages of Chagas disease and healthy individuals and to verify the determinants of peak oxygen uptake (VO2peak).

METHODS

In a cross-sectional study, 160 individuals were selected, 35 healthy and 125 with Chagas disease. In the Chagasic group, 61 (49%) were in the indeterminate form of the disease, 45 (36%) with Chagas cardiomyopathy (ChC) and preserved cardiac function and 19 (15%) with cardiac dysfunction and dilated ChC. The data were analyzed using univariate and multivariate regression analysis. Statistical significance was set at 5%.

RESULTS

Patients in the indeterminate form of disease showed similar functional capacity to healthy individuals (p>0.05). Patients with ChC and preserved cardiac function had lower VO2peak than patients in the indeterminate form (p<0.05), but showed similar VO2peak values than dilated ChC (p=0.46). The age, male sex, NYHA functional class, diastolic blood pressure, ratio of the early diastolic transmitral flow velocity to early diastolic mitral annular velocity, left ventricular ejection fraction (LVEF) and left ventricular end-diastolic diameter were associated with functional capacity. However, only age, male sex, LVEF and NYHA functional class, remained associated with VO2peak in the final model (adjusted R2=0.60).

CONCLUSION

Patients with ChC had lower functional capacity than patients in the indeterminate form. LVEF, age, male sex and NYHA functional class were determinants with VO2peak in patients with Chagas disease.

Indeterminate form of Chagas disease: historical, conceptual, clinical, and prognostic aspects

Chagas disease (CD) remains a serious endemic disease in Latin America and a major public health problem. Because of globalization, the disease has spread to non-endemic areas in the northern hemisphere. In the chronic phase of the disease, most patients present with the indeterminate form (IF), characterized by positive serology for Trypanosoma cruzi, absence of clinical findings, and normal findings in electrocardiogram (ECG). IF was not recognized as a clinical entity until decades after the discovery of the disease, and only in the 1940-50s, it was categorized as a form of CD, and its conceptual definition was ratified in the 1980s. Children, adolescents, and young adults with the IF benefit from etiological treatment and tend to have less progression to heart disease in the long term than the untreated ones. IF patients have an essentially benign clinical condition, and their prognosis can be compared to that of healthy individuals with normal ECG findings. Currently, because of aging, patients with the IF have comorbidities that require attention in health services.

Exercise tests in Chagas cardiomyopathy: an overview of functional evaluation, prognostic significance, and current challenges

Patients with Chagas cardiomyopathy (ChC) usually progress with fatigue and dyspnea. Exercise tests are valuable for the functional evaluation of these patients. However, information about the applicability of the exercise tests is scattered, and no studies have systematically reviewed the results. Thus, the present review explored the general aspects and prognostic value of exercise tests in patients with ChC. A literature search of the MEDLINE, Web of Science, CINAHL, Scopus, and LILACS databases was performed to identify relevant studies. There were no data restrictions, and articles that met the objective of the study were selected. Articles written in English, Portuguese, and Spanish were considered, and 25 articles were finally included. The peak oxygen uptake (VO2peak) was correlated with demographic and echocardiographic variables. Echocardiographic features of the left ventricular diastolic function and right ventricular systolic function appeared to be determinants of functional capacity, in addition to age and sex. VO2peak was associated with higher mortality, especially in patients with dilated ChC. The minute ventilation/carbon dioxide production slope (VE/VCO2 slope) was a strong predictor of survival; however, more studies are needed to verify this observation. Field tests showed moderate to strong correlation with VO2peak and thus may be inexpensive tools for the functional evaluation of patients with ChC. However, few studies have verified their prognostic significance. While exercise tests are useful tools for functional assessment, information is scarce regarding further considerations, and many of the criteria are based on guidelines for other heart diseases.

Influence of Angiotensin-converting Enzyme Insertion/Deletion Gene Polymorphism in Progression of Chagas Heart Disease

INTRODUCTION

Chagas disease (CD) is a neglected disease caused by the parasite Trypanosoma cruzi. One-third of infected patients will develop the cardiac form, which may progress to heart failure (HF). However, the factors that determine disease progression remain unclear. Increased angiotensin II activity is a key player in the pathophysiology of HF. A functional polymorphism of the angiotensin-converting enzyme (ACE) gene is associated with plasma enzyme activity. In CD, ACE inhibitors have beneficial effects supporting the use of this treatment in chagasic cardiomyopathy.

METHODS

We evaluated the association of ACE I/D polymorphism with HF, performing a case-control study encompassing 343 patients with positive serology for CD staged as non-cardiomyopathy (stage A; 100), mild (stage B1; 144), and severe (stage C; 99) forms of Chagas heart disease. For ACE I/D genotyping by PCR, groups were compared using unconditional logistic regression analysis and adjusted for nongenetic covariates: age, sex, and trypanocidal treatment.

RESULTS

A marginal, but not significant (p=0.06) higher prevalence of ACE I/D polymorphism was observed in patients in stage C compared with patients in stage A. Patients in stage C (CD with HF), were compared with patients in stages A and B1 combined into one group (CD without HF); DD genotype/D carriers were prevalent in the HF patients (OR = 2; CI = 1.013.96; p = 0.04).

CONCLUSIONS

Our results of this cohort study, comprising a population from the Northeast region of Brazil, suggest that ACE I/D polymorphism is more prevalent in the cardiac form of Chagas disease with HF.

Progression Rate from the Indeterminate Form to the Cardiac Form in Patients with Chronic Chagas Disease: Twenty-Two-Year Follow-Up in a Brazilian Urban Cohort

Most patients with chronic Chagas disease (CD) present the indeterminate form and are at risk to develop the cardiac form. However, the actual rate of progression to the cardiac form is still unknown. Methods: In total, 550 patients with the indeterminate CD form were followed by means of annual electrocardiogram at our outpatient clinic. The studied endpoint was progression to cardiac form defined by the appearance of electrocardiographic changes typical of CD. The progression rate was calculated as the cumulative progression rate and the incidence progression rate per 100 patient years. Results: Thirty-seven patients progressed to the CD cardiac form within a mean of 73 ± 48 months of follow-up, which resulted in a 6.9% cumulative progression rate and incidence rate of 1.48 cases/100 patient years. Patients who progressed were older (mean age 47.8 ± 12.2 years), had a higher prevalence of associated heart diseases (p < 0.0001), positive xenodiagnosis (p = 0.007), and were born in the most endemic Brazilian states (p = 0.018). Previous co-morbidities remained the only variable associated with CD progression after multivariate Cox proportional hazards regression analysis (p = 0.002). Conclusion: The progression rate to chronic CD cardiac form is low and inferior to rates previously reported in other studies.

Monocyte glycolysis determines CD8+ T cell functionality in human Chagas disease

Chagas disease is a lifelong pathology resulting from Trypanosoma cruzi infection. It represents one of the most frequent causes of heart failure and sudden death in Latin America. Herein, we provide evidence that aerobic glycolytic pathway activation in monocytes drives nitric oxide (NO) production, triggering tyrosine nitration (TN) on CD8+ T cells and dysfunction in patients with chronic Chagas disease. Monocytes from patients exhibited a higher frequency of hypoxia-inducible factor 1α and increased expression of its target genes/proteins. Nonclassical monocytes are expanded in patients' peripheral blood and represent an important source of NO. Monocytes entail CD8+ T cell surface nitration because both the frequency of nonclassical monocytes and that of NO-producing monocytes positively correlated with the percentage of TN+ lymphocytes. Inhibition of glycolysis in in vitro-infected peripheral blood mononuclear cells decreased the inflammatory properties of monocytes/macrophages, diminishing the frequency of IL-1β- and NO-producing cells. In agreement, glycolysis inhibition reduced the percentage of TN+CD8+ T cells, improving their functionality. Altogether, these results clearly show that glycolysis governs oxidative stress on monocytes and modulates monocyte-T cell interplay in human chronic Chagas disease. Understanding the pathological immune mechanisms that sustain an inflammatory environment in human pathology is key to designing improved therapies.

The Role of Co-Stimulatory Molecules in Chagas Disease

Chagas disease, caused by Trypanosoma cruzi, is a potentially life-threatening tropical disease endemic to Latin American countries that affects approximately 8 million people. In the chronic phase of the disease, individuals are classified as belonging to the indeterminate clinical form or to the cardiac and/or digestive forms when clinical symptoms are apparent. The relationship between monocytes and lymphocytes may be an important point to help clarify the complexity that surrounds the clinical symptoms of the chronic phase of Chagas disease. The co-stimulatory signals are essential to determining the magnitude of T cell response to the antigen. The signals are known to determine the regulation of subsequent adaptive immune response. However, little is known about the expression and function of these molecules in Chagas disease. Therefore, this review aims to discuss the possible role of main pathways of co-stimulatory molecule-receptor interactions in this pathology that could be crucial to understand the disease dynamics.

Electrocardiogram in Chagas disease

Since the initial descriptions of Chagas cardiomyopathy (ChCM), the electrocardiography has played a key role in patient evaluations. The diagnostic criterion of chronic ChCM is the presence of characteristic electrocardiographic (ECG) abnormalities in seropositive individuals, regardless of the presence of symptoms. However, these ECG abnormalities are rarely specific to ChCM and, particularly among the elderly, can be caused by other simultaneous cardiomyopathies. ECG abnormalities can predict the occurrence of heart failure, stroke, and even death. Nevertheless, most prognostic studies have included Chagas disease (ChD) populations and, not exclusively, ChCM. Thus, more studies are required to evaluate the efficacy of ECG in predicting reliable prognoses in established chronic ChCM. This review exclusively discusses the role of the 12-lead ECG in the clinical evaluation of chronic ChD.

Chagas Cardiomyopathy: An Update of Current Clinical Knowledge and Management: A Scientific Statement From the American Heart Association

Background:

Chagas disease, resulting from the protozoan Trypanosoma cruzi , is an important cause of heart failure, stroke, arrhythmia, and sudden death. Traditionally regarded as a tropical disease found only in Central America and South America, Chagas disease now affects at least 300 000 residents of the United States and is growing in prevalence in other traditionally nonendemic areas. Healthcare providers and health systems outside of Latin America need to be equipped to recognize, diagnose, and treat Chagas disease and to prevent further disease transmission.

Methods and Results:

The American Heart Association and the Inter-American Society of Cardiology commissioned this statement to increase global awareness among providers who may encounter patients with Chagas disease outside of traditionally endemic environments. In this document, we summarize the most updated information on diagnosis, screening, and treatment of T cruzi infection, focusing primarily on its cardiovascular aspects. This document also provides quick reference tables, highlighting salient considerations for a patient with suspected or confirmed Chagas disease.

Conclusions:

This statement provides a broad summary of current knowledge and practice in the diagnosis and management of Chagas cardiomyopathy. It is our intent that this document will serve to increase the recognition of Chagas cardiomyopathy in low-prevalence areas and to improve care for patients with Chagas heart disease around the world.

CD86 Expression by Monocytes Influences an Immunomodulatory Profile in Asymptomatic Patients with Chronic Chagas Disease

In the chronic phase of Chagas disease, 60% of the patients develop the asymptomatic form known as indeterminate (IND). The remaining 30% of the patients develop a life-threatening form in which digestive and/or cardiac (CARD) alterations take place. The mechanisms underlying the development of severe forms of Chagas disease remain poorly understood. It is well known that interactions between immune cells such as monocytes and lymphocytes drive immune responses. Further, the co-stimulatory molecules CD80 and CD86 expressed by monocytes and subsets induce lymphocyte activation, thereby triggering cellular immune response. Here, we revealed, for the first time, the functional-phenotypic profile of monocytes subsets in Chagas disease. Using flow cytometry, we evaluated the effect of in vitro stimulation with Trypanosoma cruzi antigens on the expression of the co-stimulatory molecules CD80 and CD86 in different monocyte subsets of patients with IND and CARD clinical forms of Chagas disease. We also assessed the expression of toll-like receptor (TLR)-2, TLR-4, TLR-9, HLA-DR, IL-10, and IL-12 in the monocyte subsets and of CTLA-4 and CD28, ligands of CD80 and CD86, in T lymphocytes. CD86 expression in all monocyte subsets was higher in IND patients when compared with non-infected (NI) individuals. After stimulation with T. cruzi, these patients also showed a higher frequency of CD4⁺CTLA-4⁺ T lymphocytes than NI individuals. We found an association between CD80 and CD28, and between CD86 and CTLA-4 expression, with a high frequency of regulatory T (Treg) cells in IND patients. We proposed that CD86 may be involved in immunoregulation by its association with CTLA-4 in asymptomatic patients. CD86 and CTLA-4 interaction may influence Treg activation, and this could represent a new strategy to control inflammation and tissue damage.

Predictors of death in chronic Chagas cardiomyopathy patients with pacemaker

BACKGROUND

Chronic Chagas cardiomyopathy (CCC) is the most serious and frequent manifestation of Chagas disease. Conduction abnormalities and bradycardia requiring pacemaker are common. The aim of this study was to determine the rate and predictors of death in CCC patients with pacemaker.

METHODS

In this single-center prospective cohort study we assessed the outcome of 396 CCC patients with pacemaker, followed-up for at least 24months. All patients underwent a clinical and device assessment, 12-lead electrocardiography and echocardiography.

RESULTS

During the median follow-up of 1.9years (Interquartile range 1.6-2.4), there were 65 (16.4%) deaths, yielding an annual mortality rate of 8.6%. The major cause was sudden death (33.8%), followed by heart failure (HF), 32.3%. All the investigated variables were examined as potential predictors of death. The final multivariate logistic regression model included five independent variables: advanced HF functional class (OR [odds ratio] 6.71; 95% confidence interval [95% CI] 1.95-23.2; P=0.003), renal disease (OR 5.71; 95% CI 1.80-18.0; P=0.003), QRS ≥150ms (OR 2.80; 95% CI 1.08-7.27; P=0.034), left atrial enlargement (OR 2.75; 95% CI 1.09-6.95; P=0.032) and left ventricular ejection fraction ≤43% (OR 2.31; 95% CI 1.07-4.97; P=0.032). The model had good discrimination, confirmed by bootstrap validation (optimism-adjusted c-statistic of 0.78) and the calibration curve showed a proper calibration (slope=0.972).

CONCLUSIONS

CCC patients with pacemaker have a high annual mortality rate despite that the pacemaker related variables were not predictors of death. The independent predictors of death can help us to identify the poor prognosis patients.

Combined parasitological and molecular-based diagnostic tools improve the detection of Trypanosoma cruzi in single peripheral blood samples from patients with Chagas disease

INTRODUCTION

In order to detect Trypanosoma cruzi and determine the genetic profiles of the parasite during the chronic phase of Chagas disease (ChD), parasitological and molecular diagnostic methods were used to assess the blood of 91 patients without specific prior treatment.

METHODS

Blood samples were collected from 68 patients with cardiac ChD and 23 patients with an indeterminate form of ChD, followed by evaluation using blood culture and polymerase chain reaction. T . cruzi isolates were genotyped using three different genetic markers.

RESULTS:

Blood culture was positive in 54.9% of all patients, among which 60.3% had the cardiac form of ChD, and 39.1% the indeterminate form of ChD. There were no significant differences in blood culture positivity among patients with cardiac and indeterminate forms. Additionally, patient age and clinical forms did not influence blood culture results. Polymerase chain reaction (PCR) was positive in 98.9% of patients, although comparisons between blood culture and PCR results showed that the two techniques did not agree. Forty-two T . cruzi stocks were isolated, and TcII was detected in 95.2% of isolates. Additionally, one isolate corresponded to TcIII or TcIV, and another corresponded to TcV or TcVI.

CONCLUSIONS

Blood culture and PCR were both effective for identifying T. cruzi using a single blood sample, and their association did not improve parasite detection. However, we were not able to establish an association between the clinical form of ChD and the genetic profile of the parasite.

Multimodality imaging evaluation of Chagas disease: an expert consensus of Brazilian Cardiovascular Imaging Department (DIC) and the European Association of Cardiovascular Imaging (EACVI)

Aims

To develop a document by Brazilian Cardiovascular Imaging Department (DIC) and the European Association of Cardiovascular Imaging (EACVI) to review and summarize the most recent evidences about the non-invasive assessment of patients with Chagas disease, with the intent to set up a framework for standardized cardiovascular imaging to assess cardiovascular morphologic and functional disturbances, as well as to guide the subsequent process of clinical decision-making.

Methods and results

Chagas disease remains one of the most prevalent infectious diseases in Latin America, and has become a health problem in non-endemic countries. Dilated cardiomyopathy is the most severe manifestation of Chagas disease, which causes substantial disability and early mortality in the socially most productive population leading to a significant economical burden. Prompt and correct diagnosis of Chagas disease requires specialized clinical expertise to recognize the unique features of this disease. The appropriate and efficient use of cardiac imaging is pivotal for diagnosing the cardiac involvement in Chagas disease, to stage the disease, assess patients' prognosis and address management. Echocardiography is the most common imaging modality used to assess, and follow-up patients with Chagas disease. The presence of echocardiographic abnormalities is of utmost importance, since it allows to stage patients according to disease progression. In early stages of cardiac involvement, echocardiography may demonstrate segmental left ventricuar wall motion abnormalities, mainly in the basal segments of inferior, inferolateral walls, and the apex, which cannot be attributed to obstructive coronary artery arteries. The prevalence of segmental wall motion abnormalities varies according to the stage of the disease, reaching about 50% in patients with left ventricular dilatation and dysfunction. Speckle tracking echocardiography allows a more precise and quantitative measurement of the regional myocardial function. Since segmental wall motion abnormalities are frequent in Chagas disease, speckle tracking echocardiography may have an important clinical application in these patients, particularly in the indeterminate forms when abnormalities are more subtle. Speckle tracking echocardiography can also quantify the heterogeneity of systolic contraction, which is associated with the risk of arrhythmic events. Three-dimensional (3D) echocardiography is superior to conventional two-dimensional (2D) echocardiography for assessing more accurately the left ventricular apex and thus to detect apical aneurysms and thrombus in patients in whom ventricular foreshortening is suspected by 2D echocardiography. In addition, 3D echocardiography is more accurate than 2D Simpson s biplane rule for assessing left ventricular volumes and function in patients with significant wall motion abnormalities, including aneurysms with distorted ventricular geometry. Contrast echocardiography has the advantage to enhancement of left ventricular endocardial border, allowing for more accurate detection of ventricular aneurysms and thrombus in Chagas disease. Diastolic dysfunction is an important hallmark of Chagas disease even in its early phases. In general, left ventricular diastolic and systolic dysfunction coexist and isolated diastolic dysfunction is uncommon but may be present in patients with the indeterminate form. Right ventricular dysfunction may be detected early in the disease course, but in general, the clinical manifestations occur late at advanced stages of Chagas cardiomyopathy. Several echocardiographic parameters have been used to assess right ventricular function in Chagas disease, including qualitative evaluation, myocardial performance index, tissue Doppler imaging, tricuspid annular plane systolic excursion, and speckle tracking strain. Cardiac magnetic resonance (CMR) is useful to assess global and regional left ventricular function in patients with Chagas diseases. Myocardial fibrosis is a striking feature of Chagas cardiomyopathy and late gadolinium enhancement (LGE) is used to detect and quantify the extension of myocardial fibrosis. Myocardial fibrosis might have a role in risk stratification of patients with Chagas disease. Limited data are available regarding right ventricular function assessed by CMR in Chagas disease. Radionuclide ventriculography is used for global biventricular function assessment in patients with suspected or definite cardiac involvement in Chagas disease with suboptimal acoustic window and contraindication to CMR. Myocardial perfusion scintigraphy may improve risk stratification to define cardiac involvement in Chagas disease, especially in the patients with devices who cannot be submitted to CMR and in the clinical setting of Chagas patients whose main complaint is atypical chest pain. Detection of reversible ischemic defects predicts further deterioration of left ventricular systolic function and helps to avoid unnecessary cardiac catheterization and coronary angiography.

Conclusion

Cardiac imaging is crucial to detect the cardiac involvement in patients with Chagas disease, stage the disease and stratify patient risk and address management. Unfortunately, most patients live in regions with limited access to imaging methods and point-of-care, simplified protocols, could improve the access of these remote populations to important information that could impact in the clinical management of the disease. Therefore, there are many fields for further research in cardiac imaging in Chagas disease. How to better provide an earlier diagnosis of cardiac involvement and improve patients risk stratification remains to be addressed using different images modalities.

Ribeiro AL, Cerdeira Sabino E. Mortality among blood donors seropositive and seronegative for Chagas disease (1996-2000) in São Paulo, Brazil: A death certificate linkage study

Background

Individuals in the indeterminate phase of Chagas disease are considered to have mortality rates similar to those of the overall population. This study compares mortality rates among blood donors seropositive for Chagas disease and negative controls in the city of São Paulo, Brazil.

Methodology/principal findings

This is a retrospective cohort study of blood donors from 1996 to 2000: 2842 seropositive and 5684 seronegative for Chagas disease. Death status was ascertained by performing probabilistic record linkage (RL) with the Brazil national mortality information system (SIM). RL was assessed in a previous validation study. Cox Regression was used to derive hazard ratios (HR), adjusting for confounders. RL identified 159 deaths among the 2842 seropositive blood donors (5.6%) and 103 deaths among the 5684 seronegative (1.8%). Out of the 159 deaths among seropositive donors, 26 had the 10th International Statistical Classification of Diseases and Related Health Problems (ICD-10) indicating Chagas disease as the underlying cause of death (B57.0/B57.5), 23 had ICD-10 codes (I42.0/I42.2/I47.0/I47.2/I49.0/I50.0/I50.1/ I50.9/I51.7) indicating cardiac abnormalities possibly related to Chagas disease listed as an underlying or associated cause of death, with the others having no mention of Chagas disease in part I of the death certificate. Donors seropositive for Chagas disease had a 2.3 times higher risk of death due to all causes (95% Confidence Interval (95% CI), 1.8–3.0) than seronegative donors. When considering deaths due to Chagas disease or those that had underlying causes of cardiac abnormalities related to Chagas disease, seropositive donors had a risk of death 17.9 (95% CI, 6.3–50.8) times greater than seronegative donors.

Conclusions/significance

There is an excess risk of death in donors seropositive blood for Chagas disease compared to seronegative donors. Chagas disease is an under-reported cause of death in the Brazilian mortality database.

Chagas disease is classified as one of the 17 most important neglected diseases by the World Health Organization (WHO). The majority of infected individuals live in 21 countries of Central and South America. Estimates of mortality attributable to Chagas disease vary considerably (between 0.2% and 19.2% annually). To improve the measurement of disease burden and policy decision-making in regard to treatment availability, more accurate estimates of mortality, especially among otherwise asymptomatic seropositive individuals are needed,. This study compares mortality rates and causes of death of asymptomatic blood donors who tested seropositive for Chagas disease and seronegative for all screening tests conducted in Brazil. Mortality status was ascertained by linking donor names with the Brazilian national mortality information system (SIM). The study found that donors who tested Chagas disease seropositive had risk of death from all causes 2.3 (95% CI, 1.8–3.0) times greater than seronegative ones. The data also suggest that the SIM may underestimate the total number of deaths attributable to Chagas disease in Brazil.

Does my patient have chronic Chagas disease? Development and temporal validation of a diagnostic risk score

INTRODUCTION

With the globalization of Chagas disease, unexperienced health care providers may have difficulties in identifying which patients should be examined for this condition. This study aimed to develop and validate a diagnostic clinical prediction model for chronic Chagas disease.

METHODS

This diagnostic cohort study included consecutive volunteers suspected to have chronic Chagas disease. The clinical information was blindly compared to serological tests results, and a logistic regression model was fit and validated.

RESULTS

The development cohort included 602 patients, and the validation cohort included 138 patients. The Chagas disease prevalence was 19.9%. Sex, age, referral from blood bank, history of living in a rural area, recognizing the kissing bug, systemic hypertension, number of siblings with Chagas disease, number of relatives with a history of stroke, ECG with low voltage, anterosuperior divisional block, pathologic Q wave, right bundle branch block, and any kind of extrasystole were included in the final model. Calibration and discrimination in the development and validation cohorts (ROC AUC 0.904 and 0.912, respectively) were good. Sensitivity and specificity analyses showed that specificity reaches at least 95% above the predicted 43% risk, while sensitivity is at least 95% below the predicted 7% risk. Net benefit decision curves favor the model across all thresholds.

CONCLUSIONS

A nomogram and an online calculator (available at http://shiny.ipec.fiocruz.br:3838/pedrobrasil/chronic_chagas_disease_prediction/) were developed to aid in individual risk estimation.

Rapidly Progressing Chagas Cardiomyopathy

Chagas disease, caused by the parasite Trypanosoma cruzi, can cause a potentially life-threatening cardiomyopathy in approximately 10-40% of afflicted individuals. The decline in cardiac function characteristically progresses over the course of many years. We report a case of Chagas disease in which the patient experienced an atypical rapid deterioration to severe cardiomyopathy over the course of 16 months. This case argues the need for increased routine surveillance for patients with confirmed T. cruzi infection, who are determined to be at high-risk for worsening cardiomyopathy.

Genetically Determined MBL Deficiency Is Associated with Protection against Chronic Cardiomyopathy in Chagas Disease

Chagas disease (CD) is caused by Trypanosoma cruzi, whose sugar moieties are recognized by mannan binding lectin (MBL), a soluble pattern-recognition molecule that activates the lectin pathway of complement. MBL levels and protein activity are affected by polymorphisms in the MBL2 gene. We sequenced the MBL2 promoter and exon 1 in 196 chronic CD patients and 202 controls. The MBL2*C allele, which causes MBL deficiency, was associated with protection against CD (P = 0.007, OR = 0.32). Compared with controls, genotypes with this allele were completely absent in patients with the cardiac form of the disease (P = 0.003). Furthermore, cardiac patients with genotypes causing MBL deficiency presented less heart damage (P = 0.003, OR = 0.23), compared with cardiac patients having the XA haplotype causing low MBL levels, but fully capable of activating complement (P = 0.005, OR = 7.07). Among the patients, those with alleles causing MBL deficiency presented lower levels of cytokines and chemokines possibly implicated in symptom development (IL9, p = 0.013; PDGFB, p = 0.036 and RANTES, p = 0.031). These findings suggest a protective effect of genetically determined MBL deficiency against the development and progression of chronic CD cardiomyopathy.

Chagas disease is considered an important neglected tropical disease, affecting approximately ten million people in Latin America. Although most infected individuals remain asymptomatic, one third of patients develop a chronic heart disease, with progressive inflammation, increase of myocardium, arrhythmia, cardiac insufficiency and heart failure. To date, there is no available marker to indicate the progression neither to determinate the severity of heart damage. Mannan binding lectin (MBL) is an important protein of the immune system able to recognize specific regions on the microorganism surfaces (including Trypanosoma cruzi, the causal agent of Chagas disease) which activate the complement system, a crucial mechanism of the effector immunity. MBL levels and protein activity are affected by genetic differences, named polymorphisms, in the MBL2 gene. This is the first Brazilian study with MBL2 polymorphisms in chronic Chagas disease. We sequenced two regions of MBL2 gene in 196 patients and 202 controls. We found that a polymorphism associated with deficient complement activation protects against Chagas disease and patients with deficiency-associated genotypes presented less echocardiographic alterations. Among the patients, those with alleles causing MBL deficiency presented lower levels of cytokines and chemokines possibly implicated in symptom development (IL9, p = 0.013; PDGFB, p = 0.036 and RANTES, p = 0.031). These findings lead us to suggest that genetically determined MBL deficiency plays a protective role against the development and progression of chronic Chagas disease.

Commercial enzyme-linked immunosorbent assay versuspolymerase chain reaction for the diagnosis of chronic Chagas disease: a systematic review and meta-analysis

Chronic Chagas disease diagnosis relies on laboratory tests due to its clinical characteristics. The aim of this research was to review commercial enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) diagnostic test performance. Performance of commercial ELISA or PCR for the diagnosis of chronic Chagas disease were systematically searched in PubMed, Scopus, Embase, ISI Web, and LILACS through the bibliography from 1980-2014 and by contact with the manufacturers. The risk of bias was assessed with QUADAS-2. Heterogeneity was estimated with the I2 statistic. Accuracies provided by the manufacturers usually overestimate the accuracy provided by academia. The risk of bias is high in most tests and in most QUADAS dimensions. Heterogeneity is high in either sensitivity, specificity, or both. The evidence regarding commercial ELISA and ELISA-rec sensitivity and specificity indicates that there is overestimation. The current recommendation to use two simultaneous serological tests can be supported by the risk of bias analysis and the amount of heterogeneity but not by the observed accuracies. The usefulness of PCR tests are debatable and health care providers should not order them on a routine basis. PCR may be used in selected cases due to its potential to detect seronegative subjects.

Arrhythmias in chagasic cardiomyopathy

Chagas disease, a chronic parasitosis caused by the protozoa Trypanosoma cruzi, is an increasing worldwide problem because of the number of cases in endemic areas and the migration of infected individuals to more developed regions. Chagas disease affects the heart through cardiac parasympathetic neuronal depopulation, immune-mediated myocardial injury, parasite persistence in cardiac tissue with secondary antigenic stimulation, and coronary microvascular abnormalities causing myocardial ischemia. A lack of knowledge exists for risk stratification, management, and prevention of ventricular arrhythmias in patients with chagasic cardiomyopathy. Catheter ablation can be effective for the management of recurrent ventricular tachycardia.

Early detection of left ventricular contractility abnormalities by two-dimensional speckle tracking strain in Chagas’ disease

BACKGROUND

Chagas' disease is an important cause of heart failure, and early identification of cardiac involvement may help to identify patients at risk for disease progression. Two-dimensional (2D) speckle tracking (ST) strain seems to be a useful tool to detect incipient ventricular dysfunction. This study aims to analyze if 2D strain can detect contractility abnormalities in asymptomatic patients with Chagas' disease.

METHODS

Seventy-eight asymptomatic Chagas' disease patients (46% male; age 44.7 ± 8.6 years) with normal cardiovascular exams and a control group of 38 healthy subjects (58% male; age 44.1 ± 9.2 years) were included in the study. Using 2D strain software, left ventricular (LV) end-systolic longitudinal, radial, and circumferential strain were measured. Global right ventricular (RV) longitudinal strain was also assessed.

RESULTS

Echocardiographic parameters of LV systolic and diastolic function were similar between patients and controls. 2D longitudinal strain in the basal inferior, and inferoseptal walls, as well as apical segment of the inferolateral wall were lower in patients compared with controls. 2D radial strain was reduced in several segments of the LV walls as well as the global radial strain. 2D circumferential strain at the basal segment of the anterior wall showed a lower value in patients compared with controls, whereas global circumferential strain was similar between patients and controls. 2D RV strain did not differ between groups.

CONCLUSION

In a subgroup of asymptomatic patients with Chagas' disease without evident cardiac involvement, 2D strain was reduced compared with healthy individuals, suggesting incipient LV dysfunction in these patients. 2D ST strain has the potential for detecting early myocardial impairment in the setting of Chagas' disease.

Mitochondrial dysfunction in skeletal muscle during experimental Chagas disease

Trypanosoma cruzi invasion and replication in cardiomyocytes and other tissues induce cellular injuries and cytotoxic reactions, with the production of inflammatory cytokines and nitric oxide, both sources of reactive oxygen species. The myocyte response to oxidative stress involves the progression of cellular changes primarily targeting mitochondria. Similar alterations could be taking place in mitochondria from the skeletal muscle; if that is the case, a simple skeletal muscle biopsy would give information about the cardiac energetic production that could be used as a predictor of the chagasic cardiopathy evolution. Therefore, in the present paper we studied skeletal muscle mitochondrial structure and the enzymatic activity of citrate synthase and respiratory chain complexes I to IV (CI-CIV), in Albino Swiss mice infected with T. cruzi, Tulahuen strain and SGO Z12 and Lucky isolates, along the infection. Changes in the mitochondrial structure were detected in 100% of the mitochondria analyzed from the infected groups: they all presented at least 1 significant abnormality such as increase in their matrix or disorganization of their cristae, which are probably related to the enzymatic dysfunction. When we studied the Krebs cycle functionality through the measurement of the specific citrate synthase activity, we found it to be significantly diminished during the acute phase of the infection in Tulahuen and SGO Z12 infected groups with respect to the control one; citrate synthase activity from the Lucky group was significantly increased (p<0.05). The activity of this enzyme was reduced in all the infected groups during the chronic asymptomatic phase (p<0.001) and return to normal values (Tulahuen and SGO Z12) or increased its activity (Lucky) by day 365 post-infection (p.i.). When the mitochondrial respiratory chain was analyzed from the acute to the chronic phase of the infection through the measurement of the activity of complexes I to IV, the activity of CI remained similar to control in Tulahuen and Lucky groups, but was significantly augmented in the SGO Z12 one in the acute and chronic phases (p<0.05). CII increased its activity in Tulahuen and Lucky groups by day 75 p.i. and in SGO Z12 by day 365 p.i. (p<0.05). CIII showed a similar behavior in the 3 infected groups, remaining similar to control values in the first two stages of the infection and significantly increasing later on (p<0.0001). CIV showed an increase in its activity in Lucky throughout all stages of infection (p<0.0001) and an increase in Tulahuen by day 365days p.i. (p<0.0001); SGO Z12 on the other hand, showed a decreased CIV activity at the same time. The structural changes in skeletal muscle mitochondria and their altered enzyme activity began in the acute phase of infection, probably modifying the ability of mitochondria to generate energy; these changes were not compensated in the rest of the phases of the infection. Chagas is a systemic disease, which produces not only heart damage but also permanent skeletal muscle alterations.

Right ventricular Doppler echocardiographic study of indeterminate form of chagas disease

BACKGROUND

Patients with indeterminate form of Chagas disease/cardiac normality (ICD/CN) exhibited normal electrocardiograms and chest X-rays; however, more sophisticated tests detected some degree of morphological and functional changes in the heart.

OBJECTIVE

To assess the prevalence of systolic and diastolic dysfunction of the right ventricle (RV) in patients with ICD/CN.

METHODS

This was a case-control and prevalence study. Using Doppler two-dimensional echocardiography (2D), 92 patients were assessed and divided into two groups: group I (normal, n = 31) and group II (ICD/CN, n = 61).

RESULTS

The prevalence of RV systolic dysfunction in patients in groups I and II was as follows: fractional area change (0.0% versus 0.6%), mobility of the tricuspid annulus (0.0% versus 0.0%), and S-wave tissue Doppler (6.4% versus 26.0%, p = 0.016). The prevalence of global disorders such as the right myocardial performance index using tissue Doppler (16.1% versus 27.8%, p = 0.099) and pulsed Doppler (61.3% versus 68%, p = 0.141) and diastolic disorders such as abnormal relaxation (0.0% versus 6.0%), pseudonormal pattern (0.0% versus 0.0%), and restrictive pattern (0.0% versus 0.0%) was not statistically different between groups.

CONCLUSION

The prevalence of RV systolic dysfunction was estimated to be 26% (S wave velocity compared with other variables), suggesting incipient changes in RV systolic function in the ICD/CN group.

Heart rate recovery in asymptomatic patients with Chagas disease

BACKGROUND

Chagas disease patients with right bundle-branch block (RBBB) have diverse clinical presentation and prognosis, depending on left ventricular (LV) function. Autonomic disorder can be an early marker of heart involvement. The heart rate recovery (HRR) after exercise may identify autonomic dysfunction, with impact on therapeutic strategies. This study was designed to assess the HRR after symptom-limited exercise testing in asymptomatic Chagas disease patients with RBBB without ventricular dysfunction compared to patients with indeterminate form of Chagas disease and healthy controls.

METHODS

One hundred and forty-nine subjects divided into 3 groups were included. A control group was comprised of healthy individuals; group 1 included patients in the indeterminate form of Chagas disease; and group 2 included patients with complete RBBB with or without left anterior hemiblock, and normal ventricular systolic function. A symptom-limited exercise test was performed and heart rate (HR) response to exercise was assessed. HRR was defined as the difference between HR at peak exercise and 1 min following test termination.

RESULTS

There were no differences in heart-rate profile during exercise between healthy individuals and patients in indeterminate form, whereas patients with RBBB had more prevalence of chronotropic incompetence, lower exercise capacity and lower HRR compared with patients in indeterminate form and controls. A delayed decrease in the HR after exercise was found in 17 patients (15%), 9% in indeterminate form and 24% with RBBB, associated with older age, worse functional capacity, impaired chronotropic response, and ventricular arrhythmias during both exercise and recovery. By multivariable analysis, the independent predictors of a delayed decrease in the HRR were age (odds ratio [OR] 1.11; 95% confidence interval [CI] 1.03 to 1.21; p = 0.010) and presence of RBBB (OR 3.97; 95% CI 1.05 to 15.01; p = 0.042).

CONCLUSIONS

A small proportion (15%) of asymptomatic Chagas patients had attenuated HRR after exercise, being more prevalent in patients with RBBB compared with patients in indeterminate form and controls.

Electrocardiographic abnormalities in elderly Chagas disease patients: 10-year follow-up of the Bambui Cohort Study of Aging

Background

Electrocardiography has been considered an important tool in the management of Chagas disease (ChD) patients, although its value in elderly infected patients is unknown. This study was designed to investigate the prevalence and prognostic value of electrocardiographic abnormalities in Trypanosoma cruzi infected and noninfected older adults.

Methods and Results

We studied 1462 participants in Bambuí City, Brazil, with electrocardiogram (ECG) records classified by the Minnesota Code. Follow‐up time was 10 years; the endpoint was mortality. Adjustment for potential confounding variables included age, gender, conventional risk factors, and B‐type natriuretic peptide (BNP). The mean age was 69 years (60.9% women). The prevalence of ChD was 38.1% (n=557). ECG abnormalities were more frequent in ChD patients (87.6% versus 77.7%, P<0.001). Right bundle branch block (RBBB) with left anterior hemiblock (LAH) was strongly related to ChD (OR: 11.99 [5.60 to 25.69]). During the mean follow‐up time of 8.7 years, 556 participants died (253 with ChD), and only 89 were lost to follow‐up. ECG variables of independent prognostic value for death in ChD included absence of sinus rhythm, frequent ventricular and supraventricular premature beats, atrial fibrillation, RBBB, old and possible old myocardial infarction, and left ventricular hypertrophy. The presence of any major ECG abnormalities doubled the risk of death in ChD patients (HR: 2.18 [1.35 to 3.53]), but it also increased the risk in non‐ChD subjects (HR: 1.50 [1.07 to 2.10]); the risk of death increased with the number of major abnormalities in the same patient.

Conclusion

ECG abnormalities are more common among elderly Chagas disease patients and strongly predict adverse outcomes.

Chagas disease: an overview of clinical and epidemiological aspects

Chagas disease, caused by the parasite Trypanosoma cruzi, is a serious health problem in Latin America and is an emerging disease in non-endemic countries. In recent decades, the epidemiological profile of the disease has changed due to new patterns of immigration and successful control in its transmission, leading to the urbanization and globalization of the disease. Dilated cardiomyopathy is the most important and severe manifestation of human chronic Chagas disease and is characterized by heart failure, ventricular arrhythmias, heart blocks, thromboembolic phenomena, and sudden death. This article will present an overview of the clinical and epidemiological aspects of Chagas disease. It will focus on several clinical aspects of the disease, such as chronic Chagas disease without detectable cardiac pathology, as well as dysautonomia, some specific features, and the principles of treatment of chronic cardiomyopathy.

Association of L-ficolin levels and FCN2 genotypes with chronic Chagas disease

BACKGROUND

L-ficolin (encoded by FCN2) binds to acetylated sugar moieties of many pathogens, including Trypanosoma cruzi, promoting their phagocytosis and lysis by the complement system.

METHODS

We investigated L-ficolin levels in 160 T. cruzi infected patients with chronic Chagas disease and 71 healthy individuals, and FCN2 polymorphisms (-986 G>A, -602 G>A, and -4 A>G in the promoter and A258S in exon 8) in 243 patients, being 88 indeterminate (asymptomatic), 96 with cardiac, 23 with digestive and 33 with cardiodigestive manifestations (two were unspecified) and 305 controls (135 for A258S).

RESULTS

Patients presented lower L-ficolin plasma levels than controls (p<0.0001). Among the different groups of cardiac commitment, individuals with moderate forms had higher L-ficolin levels than the severe forms (P = 0.039). Lower L-ficolin levels were found associated with the 258S variant in the patients (P = 0.034). We found less -4A/G heterozygotes in the cardiac patients, than in the controls (OR = 0.56 [95% CI = 0.33-0.94], P = 0.034). Heterozygote -4A/G genotypes with the 258S variant and 258SS homozygotes were nevertheless more frequent among cardiodigestive patients than in controls (OR = 14.1 [95% CI = 3.5-56.8], P = 0.0001) and in indeterminate patients (OR = 3.2 [95% CI = 1.1-9.4], P = 0.037). We also found an association of the allelic frequency of the 258S variant with cardiodigestive Chagas disease compared to controls (OR = 2.24 [95% CI = 1.1-4.5], P = 0.037). Thus, decreased patient levels of L-ficolin reflect not only protein consumption due to the disease process, but also the higher frequency of the 258S variant in patients with cardiodigestive symptoms.

CONCLUSION

The very first study on Brazilian cohort associates both L-ficolin plasma levels and FCN2 variants to Chagas disease and subsequent disease progression. The prognostic value of L-ficolin levels and the FCN2*A258S polymorphism should be further evaluated in other settings.

[Heart rate variability: analysis of time-domain indices in patients with chronic Chagas disease before and after an exercise program]

Chagas disease (CD) is an infection caused by the protozoan flagellate Trypanosoma cruzi, and transmitted by insects of the genera Triatoma, Rhodnius and Panstrongylus. The heart is affected to varying degrees by inflammatory and destructive lesions in atrial and ventricular myocardial fibers. Several studies have demonstrated the benefits of exercise in patients with congestive heart failure (CHF), including reduced sympathetic tone and increased parasympathetic tone, the result of reduced epinephrine and norepinephrine levels, both at rest and during exercise, including at submaximal levels. It has been hypothesized that the increase in sympathetic arousal during exercise improves peripheral muscle metabolism.

OBJECTIVES

The objectives of this study were to select patients with chronic Chagas cardiomyopathy (CCC) with dysautonomia on 24-h Holter monitoring, assess autonomic function after rehabilitation, and determine whether it resulted in reduced daytime levels of SDNN and increased daytime and nighttime levels of pNN50 and rMSSD.

METHODS

We analyzed time-domain indices of heart rate variability through 24-h Holter monitoring before and after a supervised exercise program. We studied 18 CCC patients (five men), mean age 57.33±9.73 years, followed at the CD outpatient clinic of the National Institute of Cardiology and IPEC/Fiocruz in Rio de Janeiro, Brazil, between April 2009 and November 2010. The following tests were used to assess the severity of CCC: clinical examination, functional evaluation by cardiopulmonary stress testing, electrocardiogram and conventional Doppler echocardiography. The exams were performed within a month of the start and end of the exercise program, which consisted of 60-min sessions of aerobic exercise on a treadmill and resistance training three times a week for six months. The goal was to reach the patients' heart rate target zone during training, and their rating of perceived exertion was assessed by the modified Borg scale.

RESULTS

There were no statistically significant differences (p>0.05) in SDNN, pNN50 and rMSSD, probably due to the large standard deviation observed, patients' poor adherence to the program and their low socioeconomic status, resulting in a small sample, and the short duration of the program.

CONCLUSION

Heart rate variability parameters in patients with CCC did not undergo statistically significant changes after a six-month cardiac rehabilitation program.

Antigenicity and diagnostic potential of vaccine candidates in human Chagas disease

Background

Chagas disease, caused by Trypanosoma cruzi, is endemic in Latin America and an emerging infectious disease in the US and Europe. We have shown TcG1, TcG2, and TcG4 antigens elicit protective immunity to T. cruzi in mice and dogs. Herein, we investigated antigenicity of the recombinant proteins in humans to determine their potential utility for the development of next generation diagnostics for screening of T. cruzi infection and Chagas disease.

Methods and Results

Sera samples from inhabitants of the endemic areas of Argentina-Bolivia and Mexico-Guatemala were analyzed in 1^st-phase for anti-T. cruzi antibody response by traditional serology tests; and in 2^nd-phase for antibody response to the recombinant antigens (individually or mixed) by an ELISA. We noted similar antibody response to candidate antigens in sera samples from inhabitants of Argentina and Mexico (n = 175). The IgG antibodies to TcG1, TcG2, and TcG4 (individually) and TcG_mix were present in 62–71%, 65–78% and 72–82%, and 89–93% of the subjects, respectively, identified to be seropositive by traditional serology. Recombinant TcG1- (93.6%), TcG2- (96%), TcG4- (94.6%) and TcG_mix- (98%) based ELISA exhibited significantly higher specificity compared to that noted for T. cruzi trypomastigote-based ELISA (77.8%) in diagnosing T. cruzi-infection and avoiding cross-reactivity to Leishmania spp. No significant correlation was noted in the sera levels of antibody response and clinical severity of Chagas disease in seropositive subjects.

Conclusions

Three candidate antigens were recognized by antibody response in chagasic patients from two distinct study sites and expressed in diverse strains of the circulating parasites. A multiplex ELISA detecting antibody response to three antigens was highly sensitive and specific in diagnosing T. cruzi infection in humans, suggesting that a diagnostic kit based on TcG1, TcG2 and TcG4 recombinant proteins will be useful in diverse situations.

Chagas disease is the most common cause of congestive heart failure related deaths among young adults in the endemic areas of South and Central America and Mexico. Diagnosis and treatment of T. cruzi infection has remained difficult and challenging after 100 years of its identification. In >95% of human cases, T. cruzi infection remains undiagnosed until several years later when chronic evolution of progressive disease results in clinical symptoms associated with cardiac damage. Diagnosis generally depends on the measurement of T. cruzi–specific antibodies that can result in false positives. A conclusive diagnosis of T. cruzi infection thus often requires multiple serological tests, in combination with epidemiological data and clinical symptoms. In this study, we investigated the antibody response to TcG1, TcG2, and TcG4 in clinically characterized chagasic patients. These antigens were identified as vaccine candidates and shown to elicit protective immunity to T. cruzi and Chagas disease in experimental animals. Our data show the serology test developed using the TcG_mix (multiplex ELISA) is a significantly better alternative to epimastigote extracts currently used in T. cruzi serodiagnosis or the trypomastigote lysate used in this study for comparison purposes.

Chronic indeterminate phase of Chagas’ disease: mitochondrial involvement in infection with two strains

Chagasic cardiopathy has become one of the most frequent causes of heart failure and sudden death, as well as one of the most common causes of cardio-embolic stroke in Latin America. The myocyte response to oxidative stress involves the progression of cellular changes, primarily targeting the mitochondria and modifying therefore the energy supply. In this paper we analysed the effect of the infection of mice with 2 different strains of Trypanosoma cruzi (Tulahuen and SGO Z12) in the chronic indeterminate stage (75 days post-infection), upon the structure and function of cardiac mitochondria. The structural results showed that 83% of the mitochondria from the Tulahuen-infected mice presented an increase in their matrix and 91% of the mitochondria from the SGO Z12-infected group showed a reduction in their diameter (P < 0·05). When the Krebs cycle and mitochondrial respiratory chain functionality was analysed through the measurement of the citrate synthase and complexes I to IV activity, it showed that their activity was altered in all cases in a similar manner in both infected groups. In this paper we have demonstrated that the chronic indeterminate phase is not ‘silent’ and that cardiac mitochondria are clearly involved in the genesis and progression to the chronic chagasic cardiopathy when different factors alter the host-parasite equilibrium.

Diagnosis and management of Chagas disease and cardiomyopathy

Chagas cardiomyopathy is the most severe and life-threatening manifestation of human Chagas disease--a 'neglected' tropical disease caused by the protozoan parasite Trypanosoma cruzi. The disease is endemic in all continental Latin American countries, but has become a worldwide problem because of migration of infected individuals to developed countries, mainly in Europe and North America. Chagas cardiomyopathy results from the combined effects of persistent parasitism, parasite-driven tissue inflammation, microvascular and neurogenic dysfunction, and autoimmune responses triggered by the infection. Clinical presentation varies widely according to the extent of myocardial damage, and manifests mainly as three basic syndromes that can coexist in an individual patient: heart failure, cardiac arrhythmia, and thromboembolism. NYHA functional class, left ventricular systolic function, and nonsustained ventricular tachycardia are important prognostic markers of the risk of death. Management of Chagas cardiomyopathy focuses on the treatment of the three main syndromes. The use of β-blockers in patients with Chagas disease and heart failure is safe, well tolerated, and should be encouraged. Most specialists and international institutions now recommend specific antitrypanosomal treatment of patients with chronic Chagas disease, even in the absence of evidence obtained from randomized clinical trials. Further research on the management of patients with Chagas cardiomyopathy is necessary.

IL-10 and IFN-γ gene expression in chronic Chagas disease patients after in vitro stimulation with recombinant antigens of Trypanosoma cruzi

Along with several other aspects of Chagas disease, the mechanisms responsible for the different clinical outcomes observed in chronic infected individuals have not yet been clarified. It is believed that the host immune response to the parasite plays an important role in the development of the pathology. Therefore, the aim of this study was to evaluate the relationship between IL-10 and IFN-γ gene expression profile, after in vitro stimulation of peripheral blood mononuclear cells (PBMC) with Trypanosoma cruzi recombinant antigens CRA (cytoplasmatic repetitive antigen) and FRA (flagellar repetitive antigen), and the clinical forms of chronic Chagas disease. Twenty patients with the cardiac form of the disease (CARD), of whom 10 had the mild cardiac form (CARD 1) and 10 the severe cardiac form (CARD 2), and 20 patients with the indeterminate form (IND), were selected at the Chagas Disease Unit of the Oswaldo Cruz University Hospital, University of Pernambuco, Recife, Pernambuco, Brazil. The PBMCs of these individuals were cultured in the presence of CRA or FRA for 3 days and IL-10 and IFN-γ gene expression was evaluated by detection of its messenger RNA using Real Time Quantitative PCR. Although no significant difference was observed between the groups of individuals studied, we found that most patients with IND displayed high levels of IFN-γ gene expression, while the majority of patients with CARD 1 presented high levels of IL-10. The results of this study thus highlight the important role that inflammatory cytokines play in patients with the IND group controlling for parasite replication, and that anti-inflammatory cytokines play in determining susceptibility to progression to symptomatic clinical forms of the disease.

[Association between left ventricular wall motion abnormalities and ventricular arrhythmia in the indeterminate form of Chagas disease]

INTRODUCTION

Chagas' disease can lead to severe and potentially lethal damage of cardiac function. Thus, the identification of cardiac abnormalities in patients presenting the indeterminate form (IF) can be important for risk stratification. This paper aimed to demonstrate whether IF chagasic patients who presented wall motion abnormalities showed functional and electric disturbances compared to patients with normal echocardiogram and Doppler studies.

METHODS

Thirty eight patients with the IF were studied, including 26 chagasic patients with normal electrocardiographic, radiological and echocardiographic exams and 12 chagasic patients showing segmental wall motion abnormalities in the echocardiographic exam. All the patients were submitted to complete echocardiogram and Doppler study, including tissue Doppler imaging (TDI) and Holter 24h monitoring.

RESULTS

Among the variables evaluated, significant differences among the two groups were verified in relation to: the ejection fraction (p ≤ 0.001); left ventricular systolic dimension (p = 0.029); isovolumic contraction time, measured by TDI in the basal segments of the left ventricle (p < 0.05); and the presence of isolated (p = 0.0005) and paired ventricular extrasystoles (p = 0.003), in the Holter monitoring.

CONCLUSIONS

The indeterminate form of Chagas' disease can present cardiac wall motion abnormality, demonstrating functional and electric damage compared to chagasic patients with normal echocardiogram.

Analysis of QRS loop in the Vectorcardiogram of patients with Chagas' disease

In the present work, we have studied the QRS loop in the Vectorcardiogram (VCG) of 95 chronic chagasic patients classified in different groups (I, II and III) according to their degree of myocardial damage. For comparison, the VCGs of 11 healthy subjects used as control group (Group O) were also examined. The QRS loop was obtained for each patient from the XYZ orthogonal leads of their High-Resolution Electrocardiogram (HRECG) records. In order to analyze the variations of QRS loop in each detected beat, it has been proposed in this study the following vectorcardiographic parameters a) Maximum magnitude of the cardiac depolarization vector, b) Volume, c) Area of QRS loop, d) Ratio between the Area and Perimeter, e) Ratio between the major and minor axes of the QRS loop and f) QRS loop Energy. It has been found that one or more indexes exhibited statistical differences (p < 0.05) between groups 0-II, O-III, I-II, I-III and II-III. We concluded that the proposed method could be use as complementary diagnosis technique to evaluate the degree of myocardial damage in chronic chagasic patients.

Chagas cardiomyopathy--where do we stand after a hundred years?

A hundred years from its description, Chagas cardiomyopathy remains a challenging disease. Although successful vector-control strategies have decreased the incidence of Chagas disease in several Latin American countries, both migration to urban areas and immigration have spread the disease worldwide; and now, blood transfusion, organ transplantation, and vertical transmission are a concern. The pathogenesis of Chagas cardiomyopathy involves complex host-parasite interactions, where low-grade but incessant systemic infection and triggered autoimmune reaction are the main mechanisms for its development, with the contribution of autonomic damage and microvascular disturbances. Chagas cardiomyopathy is the most important clinical presentation of Chagas disease and comprises a wide range of manifestations, including heart failure, arrhythmias, heart blocks, sudden death, thromboembolism, and stroke. Recently, simple clinical prognostic scores have been developed to identify high-risk patients and help with management. The treatment of Chagas cardiomyopathy focuses mostly on managing heart failure, arrhythmias, and thromboembolism. The role of specific antiparasitic therapy in the chronic form is not yet defined, and a randomized trial is now under way to address this crucial point. In this article, we review the main clinical aspects of Chagas cardiomyopathy and underscore some upcoming challenges for the appropriate control, diagnosis, and management of this complex disease.

Some components of the cardiac β-adrenergic system are altered in the chronic indeterminate form of experimental Trypanosoma cruzi infection

The chronic indeterminate form of Trypanosoma cruzi infection could be the key to knowing which patients will develop chagasic myocardiopathy. Infected mice present a period in which cardiac functional and structural alterations are different from those described for acute or chronic phases. We studied some components of the cardiac β-adrenergic system in mouse hearts infected with T. cruzi Tulahuen strain or SGO-Z12 isolate during the chronic indeterminate phase of infection. We determined: (i) the primary messenger (epinephrine and norepinephrine) levels in plasma by reverse-phase-HPLC; (ii) the cardiac β-adrenergic receptors' (β-AR) density and affinity by binding with tritiated dihidroalprenolol and by immunofluorescence; (iii) the cardiac concentration of the second messenger (cAMP) (by ELISA) given its importance for the phosphorylation of the proteins involved in cardiac contraction; (iv) the cardiac contractility and functional studies of the β-ARs as a response to the ligand binding to the receptor; and (v) the left ventricular ejection fraction as a measure of in vivo cardiac function. Plasma catecholamines levels remained similar to those found in uninfected controls. The β-ARs' affinity decreased in both infected groups compared with the uninfected group (P<0.05) while the receptors' density increased only in the SGO-Z12 group (P<0.01). Cyclic AMP levels were higher in both infected groups (P<0.01) relative to controls, and were higher in SGO-Z12-infected mice compared with those infected with the Tulahuen strain. However, the basal contractile force remained unchanged and the response to catecholamines only increased in the Tulahuen group (P<0.05). The left ventricular ejection fraction, on the other hand, was diminished in SGO-Z12-infected mice. Heterogeneity between T. cruzi strains determine, in the chronic indeterminate form, alterations in the signaling pathways of the β-adrenergic system at different levels: (i) between catecholamines and the β(1)-receptors; (ii) between the receptors' activation and the adenylyl-cyclase activation; and/or (iii) between cAMP and the contractile response.