Chagasic Disease Research Articles

Chagas Disease, A Review of the Literature

Chagas disease is a vector-borne (triatomine) infection caused by the protozoan parasite Trypanosoma cruzi. Synonyms for this disease are: American trypanosomiasis, Chagas disease and T. cruzi infection. 10, 5 The most common form of transmission of Chagas disease is through hematophagous triatomine insects (triatominae), which develop in dwellings in precarious conditions, The disease can also be transmitted by blood transfusion, organ transplantation, oral and congenital routes, and even more rarely by exceptional routes such as sexual contact and non-Triatominae vectors. American Trypanosomiasis is endemic in much of Mexico, Central and South America 1,11. it is estimated that ~6 million individuals are infected throughout Latin America, while ~300,000 are infected in the U.S.1, 10, 11,16 Chagas disease has two clearly differentiated phases. Initially, the acute phase lasts about two months after infection, they may have a skin lesion or a purplish swelling of an eyelid, they may have fever, headache, enlarged lymph nodes, pallor, muscle aches, shortness of breath, swelling, and abdominal or chest pain. During the chronic phase, the infection can cause sudden death due to cardiac arrhythmias or progressive heart failure due to destruction of the cardiac muscle and its innervations. 15 Appropriate diagnostics for acute infection, nucleic acid amplification testing (NAAT) from blood is recommended; For chronic infection, serological testing is employed. Antitrypanosomal agents, benznidazole and nifurtimox, have shown efficacy in treating T. cruzi infection, The most serious complication is chronic chagasic heart disease, since it is the main cause of death in sick patients. 16

Intra-host Trypanosoma cruzi strain dynamics shape disease progression: the missing link in Chagas disease pathogenesis.

Chronic Chagasic cardiomyopathy develops years after infection in 20-40% of patients, but disease progression is poorly understood. Here, we assessed Trypanosoma cruzi parasite dynamics and pathogenesis over a 2.5-year period in naturally infected rhesus macaques. Individuals with better control of parasitemia were infected with a greater diversity of parasite strains compared to those with increasing parasitemia over time. Also, the in vivo parasite multiplication rate decreased with increasing parasite diversity, suggesting competition among strains or a stronger immune response in multiple infections. Significant differences in electrocardiographic (ECG) profiles were observed in Chagasic macaques compared to uninfected controls, suggesting early conduction defects, and changes in ECG patterns over time were observed only in macaques with increasing parasitemia and lower parasite diversity. Disease progression was also associated with plasma fibronectin degradation, which may serve as a biomarker. These data provide a novel framework for the understanding of Chagas disease pathogenesis, with parasite diversity shaping disease progression.IMPORTANCEChagas disease progression remains poorly understood, and patients at increased risk of developing severe cardiac disease cannot be distinguished from those who may remain asymptomatic. Monitoring of Trypanosoma cruzi strain dynamics and pathogenesis over 2-3 years in naturally infected macaques shows that increasing parasite diversity in hosts is detrimental to parasite multiplication and Chagasic cardiomyopathy disease progression. This provides a novel framework for the understanding of Chagas disease pathogenesis.

Prevalencia de alteraciones digestivas asociadas a Chagas importado (estudio PADChI): un estudio observacional

BackgroundChagas disease (CD) is a parasitic disease caused by Trypanosoma cruzi in which up to 10% to 20% of those affected may experience digestive disorders. Multiple studies have been carried out on CD in non-endemic countries, mainly related to cardiological involvement. However, digestive disorders have not been analyzed in such depth. The objective of the study was to determine the prevalence of digestive disorders in imported CD at the time of first care. MethodsAn observational, cross-sectional, descriptive analysis of imported CD was performed. Chagasic structural damage and infectious digestive comorbidity were evaluated. The association between Chagasic structural damage and heart disease in Chagas patients was also investigated. ResultsAfter reviewing a total of 1,216 medical records, those of 464 patients were selected for analysis. Globally, the prevalence of digestive disorders in imported Chagas was 57.76% (95%CI: 53.25-62.27). The prevalence of infectious disease comorbidity was 40.73% (95%CI: 36.25-45.22). Colonic abnormalities were found in 84 of 378 barium enema patients. CD-related esophageal abnormalities were present in 63 of 380 patients studied by means of an esophagram. ConclusionsThe prevalence of digestive disorders associated with CD is high. Therefore, the presence of infectious diseases (mainly parasitic diseases and Helicobacter pylori infection) should be ruled out. It is important to rule out structural involvement in all symptomatic patients and asymptomatic patients should also be considered and offered the option of doing so.

Prevalence of digestive disorders associated with imported Chagas disease (PADChI study): an observational study

BackgroundChagas disease (CD) is a parasitic disease caused by Trypanosoma cruzi, in which up to 10–20% of those affected may suffer digestive disorders. Multiple studies have been carried out on CD in non-endemic countries, mainly related to cardiological involvement. However, digestive disorders have not been analyzed in such depth. The objective of the study was to determine the prevalence of digestive disorders in imported CD at the time of first care. MethodsAn observational cross-sectional descriptive analysis of imported CD was performed. Chagasic structural damage and infectious digestive comorbidity were evaluated. The association between Chagasic structural damage and heart disease in Chagas patients was also investigated. ResultsAfter reviewing a total of 1,216 medical records, those of 464 patients were selected for analysis. Globally, the prevalence of digestive disorders in imported Chagas was 57.76%, 95% CI (53.25–62.27). The prevalence of comorbidity of infectious diseases was 40.73% CI 95% (36.25–45.22). Colonic abnormalities were found in 84 of 378 barium enema patients. CD-related esophageal abnormalities were present in 63 of 380 patients studied with esophagogram. ConclusionsThe prevalence of digestive disorders associated with CD is high, so the presence of infectious diseases (mainly parasitic and H. pylori infection) should be ruled out. It is important to exclude structural involvement in all symptomatic patients, and asymptomatic patients should also be considered and offered.

Prophylactic low-dose, bi-weekly benznidazole treatment fails to prevent Trypanosoma cruzi infection in dogs under intense transmission pressure.

Trypanosoma cruzi naturally infects a wide variety of wild and domesticated mammals, in addition to humans. Depending on the infection dose and other factors, the acute infection can be life-threatening, and in all cases, the risk of chagasic heart disease is high in persistently infected hosts. Domestic, working, and semi-feral dogs in the Americas are at significant risk of T. cruzi infection and in certain settings in the southern United States, the risk of new infections can exceed 30% per year, even with the use of vector control protocols. In this study, we explored whether intermittent low-dose treatment with the trypanocidal compound benznidazole (BNZ) during the transmission season, could alter the number of new infections in dogs in an area of known, intense transmission pressure. Preliminary studies in mice suggested that twice-weekly administration of BNZ could prevent or truncate infections when parasites were delivered at the mid-point between BNZ doses. Pre-transmission season screening of 126 dogs identified 53 dogs (42.1%) as T. cruzi infection positive, based upon blood PCR and Luminex-based serology. Serial monitoring of the 67 uninfected dogs during the high transmission season (May to October) revealed 15 (22.4%) new infections, 6 in the untreated control group and 9 in the group receiving BNZ prophylaxis, indicating no impact of this prophylaxis regimen on the incidence of new infections. Although these studies suggest that rigorously timed and more potent dosing regimen may be needed to achieve an immediate benefit of prophylaxis, additional studies would be needed to determine if drug prophylaxis reduced disease severity despite this failure to prevent new infections.

First appropriate implantable defibrillator shocks in patients with Chagasic heart disease

ResumenObjetivos:Determinar si los pacientes con cardiopatía chagásica (CCh) presentaron choques apropiados del desfibrilador automático implantable (DAI) de manera más precoz que los pacientes con cardiopatía isquémica (CI).Métodos:Estudio de cohorte retrospectivo que incluyó los pacientes con CCh y CI en quienes se implantó un DAI entre los años 2009 y 2018 en un hospital de alta complejidad. El seguimiento se realizó hasta los 36 meses, evaluándose el momento del primer choque apropiado del dispositivo.Resultados:Se incluyeron 64 pacientes, 20 con CCh y 44 con CI. Se observó que una mayor proporción de pacientes con CCh presentaron choques apropiados durante el primer año (hazard ratio [HR]: 8.4; intervalo de confianza del 95% [IC95%]: 2.09-34.02; p = 0.0027) y a 3 años (HR: 4.61; IC95%: 1.51-14.07; p = 0.0072). El 100% de la población con CCh e implante del DAI como prevención secundaria de muerte súbita presentaron choques apropiados durante los primeros 26 meses de seguimiento.Conclusiones:Los pacientes con CCh presentaron choques apropiados del DAI de manera más precoz que los pacientes con CI. Todos los pacientes con CCh y DAI como prevención secundaria presentaron choques apropiados, representando una población de mayor riesgo. Esta información apoya la indicación del DAI en estos pacientes a pesar de la escasa evidencia en ensayos aleatorizados.

Circulating miR-146a as a possible candidate biomarker in the indeterminate phase of Chagas disease

BackgroundChagas disease is considered important and presents intense inflammatory and fibrotic processes induced by the perpetuation of the parasite in the affected tissues and organs. Therefore, it is necessary to inquire about the host defense and attack mechanisms to have a more detailed knowledge about Chagas disease. MicroRNAs are found in blood, tissues and extracellular vesicles. These small regulators of gene expression are involved in physiological and pathological processes in both mammals and parasites. Several microRNAs have deregulated expression in chagasic heart disease, although little is known about their extracellular expression. Our main objective was to evaluate the involvement of miR-21, miR-146a and miR-155 in several samples from mice infected with the TcI Ninoa strain from the acute and indeterminate phases. We also explored a potential functional association of the selected microRNAs using STRING software. This software identified 23 pathways associated with Trypanosoma cruzi infection. In addition, eleven genes were identified through bioinformatics analysis, and we found that SMAD family member 5 was downregulated in both phases. This gene serves as a mediator in the TGF-β signaling pathway. Thus, forty female mice of the CD1 strain were distributed into 4 groups and the expression levels of miR-21, miR-146a and miR-155 were measured in samples of heart tissue, total plasma and plasma extracellular vesicles by quantitative real-time polymerase chain reaction.ResultsOverexpression of miR-21, miR-146a and miR-155 was observed in heart and plasma in both phases. Moreover, in extracellular vesicles miR-21 and miR-146a were also overexpressed in the acute phase, whereas in the indeterminate chronic phase we found only miR-146a up-regulated.ConclusionsThe expression of inflammatory microRNAs miR-21, miR-146a and miR-155 were up-regulated in each of the samples from acutely and chronically infected mice. The relevant finding was that miR-146a was up-regulated in each sample in both phases; therefore, this miRNA could be a possible candidate biomarker in Chagas disease.

Levels of anti-B13 antibodies over time in a cohort of chronic infected by Trypanosoma cruzi. Its relationship with specific treatment and clinical status

The immunodominant B13 protein of Trypanosoma cruzi is found on the surface of trypomastigotes and exhibits cross-reactivity with the human cardiac myosin heavy chain; for which antibodies against this parasitic antigen may be involved in the development of disease pathology. In a cohort of chronically T. cruzi-infected adults, undergoing trypanocidal treatment, or not, we, therefore, decided to evaluate the levels of anti-B13 antibodies (ELISA-B13) and its eventual relationship with heart complaints. Two hundred twenty-eight serum samples from 76 chronically infected adults with an average follow-up of 24 years were analyzed. Thirty of them had received trypanocidal treatment. Among treated patients, anti-B13 Ab levels in successive samples showed a significant decrease in reactivity as the years after treatment increased (ANOVA test, p=0.0049). At the end of the follow-up, 36.7% became non-reactive for ELISA B13. Untreated patients did not have significant variations in the level of anti-B13 antibodies during follow-up. None of the treated patients had electrocardiographic changes compatible with chronic chagasic cardiomyopathy, whereas 21.7% of those undergoing no treatment did show such kind of pathological electrocardiogram tracings. ELISA-B13 was reactive in all cases with heart involvement. Among untreated patients, there were no significant differences in anti-B13 antibodies when comparing individuals without proven pathology with those with chronic chagasic cardiomyopathy. Although treatment with trypanocidal drugs was followed by decreased anti-B13 antibody levels, such assessment was unhelpful in differentiating the evolution of chronic chagasic heart disease.

Oral Trypanosoma cruzi Transmission Resulting in Advanced Chagasic Cardiomyopathy in an 11-Month-Old Male

Our case report describes the youngest clinical acute Chagas disease case and their unusual disease presentation of cardiac failure. In parts of the Brazilian Amazon, cultural practices include weaning infants from breastmilk to solid foods with açaí consumption serving as an intermediary. This practice could place infants at an increased risk of oral Trypanosoma cruzi infection and severe Chagasic cardiac disease.

Nutritional Status Evaluation of a Critically Ill Patient with Chagasic Cardiopathy Treated in an Intensive Care Unit in Santo Antonio de Jesus, Bahia, Brazil: A Case Report

Malnutrition at hospital admission has negative impact on clinical outcomes such as patients' hospital length of stay, rehospitalization and death. The aim of the current study is to present a case report describing the nutritional status of a critically ill patient with chagasic heart disease who was hospitalized in the intensive care unit of a hospital in Santo Antonio de Jesus County, Bahia State.

Preliminary study between Y chromosome haplogroups and chagasic cardiomyopathy manifestations in patients with Chagas disease.

INTRODUCTION: Among patients with Chagas disease, men have a higher risk of worse pathological symptoms than women. We aimed to explore the role of the Y chromosome in men diagnosed with Chagas disease and assess the relationship between their ancestry and disease status. METHODS In this comparative study, we analyzed 150 men with unrelated non-chagasic disease (nCD) and 150 men with unrelated chagasic disease (CD). We assessed the serological diagnosis of Chagas disease, biochemical parameters, thoracic X-rays, electrocardiogram, and transthoracic echocardiography and determined the haplogroup by analyzing a set of 17 microsatellites from the Y chromosome. We examined the associations between common Y chromosome haplogroups and the clinical parameters of risk by logistic regression.RESULTS For all patients, the most common haplogroups were R1b (43%), G2a (9%), and E1b1b (9%). The R1b and G2a haplogroup was more frequent in men with nCD and CD, respectively. As expected, we observed a high proportion of symptomatic patients in the CD group independent of the haplogroups. Men from both groups classified as having the R1b haplogroup showed less clinical evidence of disease. Multivariate analysis showed that CD patients without R1b were about five times more likely to have a cardio-thorax index >0.5% (OR [odds ratio] = 5.1, 95% CI [confidence interval] = 3.31-8.17). Men without the R1b haplogroup were 2.5 times more likely to show EcoCG alterations (OR = 2.50, 95% CI = 0.16-3.94). CONCLUSIONS: Our results provided evidence that the R1b haplogroup may have a potential protective cardiovascular effect for its carriers.

Biomarkers of Oxidative Stress and Inflammation in Chagasic Myocardiopathy

Introduction:The fact that only part of the population that lives in endemic areas gets Chagas disease and that only some of the patients with chronic infection develop symptoms, supports the importance of investigating the factors of each host in the susceptibility and the development of the disease. Chronic pathological processes and progressive inflammation lead to alterations in the cellular antioxidant status. This imbalance would contribute to the destruction of the parasite and would be related to the cardiac damage observed in patients with chagasic cardiomyopathy.Objective:The objective of the present study was to determine the plasma activity of oxidative stress and inflammatory biomarkers: SOD, CAT, GPx, TBARS and TNF-α in chagasic patients with and without cardiomyopathy and healthy individuals.Aim:The aim of the present study is to demonstrate the predisposition to severe forms of chagasic heart disease by quantifying the biomarkers mentioned in blood from the study population.Results and Conclusion:The results show significant differences in the enzymatic activities in the different groups of patients, which would mean at the cellular level, an alteration of the antioxidant capacity. Contrary to what we expected (a depletion of these enzymes), patients show an increase in antioxidant activity, that is, they respond to the generation of free radicals. The same trend is observed in the case of TBARS that are elevated in the case of chagasic patients, indicating a high degree of lipid peroxidation and oxidative damage. Regarding TNF-α levels, we found statistically significant differences, which show an active and chronic inflammatory state in these patients. Although we have found significant differences between the CN group and the other groups of patients, we should indicate that between the MCC and ECsinMCC groups, the results obtained did not show marked differences. This is important since it has been shown that patients infected with Tc have a marked antioxidant potential and are able to respond to the oxidative stress induced by the parasite, although this would not be decisive in the evolution of the disease.

Assessing the Effectiveness of Curative Benznidazole Treatment in Preventing Chronic Cardiac Pathology in Experimental Models of Chagas Disease.

Chagasic heart disease develops in 30% of those infected with the protozoan parasite Trypanosoma cruzi, but can take decades to become symptomatic. Because of this, it has been difficult to assess the extent to which antiparasitic therapy can prevent the development of pathology. We sought to address this question using experimental murine models, exploiting highly sensitive bioluminescent imaging to monitor curative efficacy. Mice were inoculated with bioluminescent parasites and then cured in either the acute or chronic stage of infection with benznidazole. At the experimental endpoint (5 to 6 months postinfection), heart tissue was removed and assessed for inflammation and fibrosis, two widely used markers of cardiac pathology. Infection of BALB/c and C3H/HeN mice with distinct T. cruzi lineages resulted in greatly increased myocardial collagen content at a group level, indicative of fibrotic pathology. When mice were cured by benznidazole in the acute stage, the development of pathology was completely blocked. However, if treatment was delayed until the chronic stage, cardiac fibrosis was observed in the BALB/c model, although the protective effect was maintained in the case of C3H/HeN mice. These experiments therefore demonstrate that curative benznidazole treatment early in murine T. cruzi infections can prevent the development of cardiac fibrosis. They also show that treatment during the chronic stage can block pathology but the effectiveness varies between infection models. If these findings are extendable to humans, it implies that widespread chemotherapeutic intervention targeted at early-stage infections could play a crucial role in reducing Chagas disease morbidity at a population level.

Canonical PI3K\u03b3 signaling in myeloid cells restricts Trypanosoma cruzi infection and dampens chagasic myocarditis

Chagas disease is caused by infection with the protozoan Trypanosoma cruzi (T. cruzi) and is an important cause of severe inflammatory heart disease. However, the mechanisms driving Chagas disease cardiomyopathy have not been completely elucidated. Here, we show that the canonical PI3Kγ pathway is upregulated in both human chagasic hearts and hearts of acutely infected mice. PI3Kγ-deficient mice and mutant mice carrying catalytically inactive PI3Kγ are more susceptible to T. cruzi infection. The canonical PI3Kγ signaling in myeloid cells is essential to restrict T. cruzi heart parasitism and ultimately to avoid myocarditis, heart damage, and death of mice. Furthermore, high PIK3CG expression correlates with low parasitism in human Chagas’ hearts. In conclusion, these results indicate an essential role of the canonical PI3Kγ signaling pathway in the control of T. cruzi infection, providing further insight into the molecular mechanisms involved in the pathophysiology of chagasic heart disease.

Pathogenesis of Chronic Chagas Disease: Macrophages, Mitochondria, and Oxidative Stress

Trypanosoma cruzi is the causative agent of Chagas disease. Decades after initial infection, ~30% of individuals can develop chronic chagasic cardiomyopathy. There are several proposed mechanisms for pathogenesis of Chagas disease, including parasite persistence, immune responses against parasite or self that continue in the heart, vascular compromise, and involvement of autonomous and central nervous system. Herein, we will focus on the significance of macrophages, mitochondrial dysfunction, and oxidative stress in progression of chagasic cardiomyopathy. The current literature suggests that T. cruzi prevents cytotoxic activities of the innate immune cells and persists in the host, contributing to mitochondrial oxidative stress. We discuss how the neoantigens generated due to cellular oxidative damage contribute to chronic inflammatory stress in chagasic disease. We propose that metabolic regulators, PARP-1/SIRT1, determine the disease outcome by modulating the mitochondrial and macrophage stress and antioxidant/oxidant imbalance, and offer a potential new therapy against chronic Chagas disease.

Case 3/2018 - A 60-year-old female with Chagasic heart disease, admitted due to heart failure decompensation, cachexia and pulmonary infection

Aspectos clinicos Iniciamos a discussao pela lista de problemas: 60 anos, dispneia, tosse seca, perda ponderal, subfebril, anemia, aumento dos hilos pulmonares, calcificacoes hilares (linfonodos sequelares) e nodulo pulmonar (granuloma com necrose). Como antecedentes, existiam doenca de Chagas (nao havia confirmacao, pois nao tinha sorologia para doenca de Chagas), hipertensao arterial sistemica, insuficiencia cardiaca de fracao de ejecao reduzida, com areas de acinesia e aneurisma de ponta e taquicardia ventricular sustentada previa. Dentre as doencas granulomatosas, a sarcoidose possui sintomas [...]

Bone marrow cell migration to the heart in a chimeric mouse model of acute chagasic disease.

BACKGROUND Chagas disease is a public health problem caused by infection with the protozoan Trypanosoma cruzi. There is currently no effective therapy for Chagas disease. Although there is some evidence for the beneficial effect of bone marrow-derived cells in chagasic disease, the mechanisms underlying their effects in the heart are unknown. Reports have suggested that bone marrow cells are recruited to the chagasic heart; however, studies using chimeric mouse models of chagasic cardiomyopathy are rare.OBJECTIVES The aim of this study was to investigate the migration of bone marrow cells to the heart after T. cruzi infection in a model of chagasic disease in chimeric mice.METHODS To obtain chimerical mice, wild-type (WT) C57BL6 mice were exposed to full body irradiation (7 Gy), causing bone marrow ablation. Then, bone marrow cells from green fluorescent protein (GFP)-transgenic mice were infused into the mice. Graft effectiveness was confirmed by flow cytometry. Experimental mice were divided into four groups: (i) infected chimeric (iChim) mice; (ii) infected WT (iWT) mice, both of which received 3 × 104 trypomastigotes of the Brazil strain; (iii) non-infected chimeric (Chim) mice; and (iv) non-infected WT mice.FINDINGS At one-month post-infection, iChim and iWT mice showed first degree atrioventricular block with decreased heart rate and treadmill exercise parameters compared to those in the non-infected groups.MAIN CONCLUSIONS iChim mice showed an increase in parasitaemia, myocarditis, and the presence of amastigote nests in the heart tissue compared to iWT mice. Flow cytometry analysis did not detect haematopoietic progenitor cells in the hearts of infected mice. Furthermore, GFP+ cardiomyocytes were not detected in the tissues of chimeric mice.

Infectious diseases causing autonomic dysfunction.

To review infectious diseases that may cause autonomic dysfunction. Review of published papers indexed in medline/embase. Autonomic dysfunction has been reported in retrovirus (human immunodeficiency virus (HIV), human T-lymphotropic virus), herpes viruses, flavivirus, enterovirus 71 and lyssavirus infections. Autonomic dysfunction is relatively common in HIV-infected patients and heart rate variability is reduced even in early stages of infection. Orthostatic hypotension, urinary dysfunction and hypohidrosis have been described in tropical spastic paraparesis patients. Varicella zoster reactivation from autonomic ganglia may be involved in visceral disease and chronic intestinal pseudo-obstruction. Autonomic and peripheral nervous system dysfunction may happen in acute tick-borne encephalitis virus infections. Hydrophobia, hypersalivation, dyspnea, photophobia, and piloerection are frequently observed in human rabies. Autonomic dysfunction and vagal denervation is common in Chagas disease. Neuronal depopulation occurs mainly in chagasic heart disease and myenteric plexus, and megacolon, megaesophagus and cardiomyopathy are common complications in the chronic stage of Chagas disease. Parasympathetic autonomic dysfunction precedes left ventricle systolic dysfunction in Chagas disease. A high prevalence of subclinical autonomic neuropathy in leprosy patients has been reported, and autonomic nerve dysfunction may be an early manifestation of the disease. Autonomic dysfunction features in leprosy include anhidrosis, impaired sweating function, localised alopecia ,and reduced heart rate variability. Urinary retention and intestinal pseudo-obstruction have been described in Lyme disease. Diphtheritic polyneuropathy, tetanus and botulism are examples of bacterial infections releasing toxins that affect the autonomic nervous system. Autonomic dysfunction may be responsible for additional morbidity in some infectious diseases.

Molecular identification and genotyping of Trypanosoma cruzi DNA in autochthonous Chagas disease patients from Texas, USA

The parasitic protozoan Trypanosoma cruzi, the causative agent of Chagas disease, is widely distributed throughout the Americas, from the southern United States (US) to northern Argentina, and infects at least 6 million people in endemic areas. Much remains unknown about the dynamics of T. cruzi transmission among mammals and triatomine vectors in sylvatic and peridomestic eco-epidemiological cycles, as well as of the risk of transmission to humans in the US. Identification of T. cruzi DTUs among locally-acquired cases is necessary for enhancing our diagnostic and clinical prognostic capacities, as well as to understand parasite transmission cycles. Blood samples from a cohort of 15 confirmed locally-acquired Chagas disease patients from Texas were used for genotyping T. cruzi. Conventional PCR using primers specific for the minicircle variable region of the kinetoplastid DNA (kDNA) and the highly repetitive genomic satellite DNA (satDNA) confirmed the presence of T. cruzi in 12/15 patients. Genotyping was based on the amplification of the intergenic region of the miniexon gene of T. cruzi and sequencing. Sequences were analyzed by BLAST and phylogenetic analysis by Maximum Likelihood method allowed the identification of non-TcI DTUs infection in six patients, which corresponded to DTUs TcII, TcV or TcVI, but not to TcIII or TcIV. Two of these six patients were also infected with a TcI DTU, indicating mixed infections in those individuals. Electrocardiographic abnormalities were seen among patients with single non-TcI and mixed infections of non-TcI and TcI DTUs. Our results indicate a greater diversity of T. cruzi DTUs circulating among autochthonous human Chagas disease cases in the southern US, including for the first time DTUs from the TcII-TcV-TcVI group. Furthermore, the DTUs infecting human patients in the US are capable of causing Chagasic cardiac disease, highlighting the importance of parasite detection in the population.

Dantrolene improves in vitro structural changes induced by serum from Trypanosoma cruzi-infected mice

Dystrophin, an important protein of the dystrophin-glycoprotein complex, has been implicated in the pathogenesis of experimental Chagas disease. It is important for the maintenance of cell shape and contraction force transmission. Dystrophin loss has been related to end-stage cardiac myopathies and proposed as a common route for myocardial dysfunction and progression to advanced heart failure. Evidence suggests that calpains, calcium-dependent proteases, digest dystrophin when the calcium concentration is compatible with their activation. The objective of this in vitro study was to test the hypothesis that dantrolene, a calcium channel blocker, improves structural changes induced by serum from Trypanosoma cruzi-infected mice. Cultured neonatal cardiac myocytes were incubated with serum from T. cruzi-infected mice and treated with dantrolene for 24h. Immunofluorescence and immunoblotting were performed to evaluate dystrophin and calpain-1 protein expression. The levels of dystrophin decreased 13% and calpain increased 17% after incubation of cultured neonatal cardiac myocytes with serum from T. cruzi-infected mice. The treatment with dantrolene restored the dystrophin and calpain levels near control levels. Our results demonstrate that alterations in calcium homeostasis in cardiac myocytes are responsible, in part, for cardiac structural changes in experimentally induced T. cruzi myocarditis and that calpain inhibitors may be beneficial in Chagasic heart disease.