Main Cardiac Histopathologic Alterations in the Acute Phase of Trypanosoma cruzi Infection in a Murine Model.

Symptoms in the acute phase of Chagas disease are usually mild and nonspecific. However, after several years, severe complications like dilated heart failure and even death may arise in the chronic phase. Due to the lack of specific symptoms in the acute phase, the aim of this work was to describe and analyze the cardiac histopathology during this phase in a CD1 mouse model by assessing parasitism, fibrotic damage, and the presence and composition of a cellular infiltrate, to determine its involvement in the pathogenesis of lesions in the cardiac tissue. Our results indicate that the acute phase lasts about 62 days post-infection (dpi). A significant increase in parasitemia was observed since 15 dpi, reaching a maximum at 33 dpi (4.1 × 106). The presence of amastigote nests was observed at 15-62 dpi, with a maximum count of 27 nests at 35 dpi. An infiltrate consisting primarily of macrophages and neutrophils was found in the cardiac tissue within the first 30 days, but the abundance of lymphocytes showed an 8 ≥ fold increase at 40-62 dpi. Unifocal interstitial fibrosis was identified after 9 dpi, which subsequently showed a 16 ≥ fold increase at 40-60 dpi, along with a 50% mortality rate in the model under study. The increased area of fibrotic lesions revealed progression in the extent of fibrosis, mainly at 50-62 dpi. The presence of perivasculitis and thrombus circulation disorders was seen in the last days (62 dpi); finally, cases of myocytolysis were observed at 50 and 62 dpi. These histopathological alterations, combined with collagen deposition, seem to lead to the development of interstitial fibrosis and damage to the cardiac tissue during the acute phase of infection. This study provides a more complete understanding of the patterns of histopathological abnormalities involved in the acute phase, which could help the development of new therapies to aid the preclinical tests of drugs for their application in Chagas disease.

Expression of Proteins, Glycoproteins, and Transcripts in the Guts of Fasting, Fed, and Trypanosoma cruzi-Infected Triatomines: A Systematic Review.

Chagas disease is caused by the hemoflagellate protozoan Trypanosoma cruzi. The main transmission mechanism for the parasite in endemic areas is contact with the feces of an infected triatomine bug. Part of the life cycle of T. cruzi occurs in the digestive tract of triatomines, where vector and parasite engage in a close interaction at a proteomic-molecular level. This interaction triggers replication and differentiation processes in the parasite that can affect its infectivity for the vertebrate host. With the aim of compiling and analyzing information from indexed publications on transcripts, proteins, and glycoproteins in the guts of fasting, fed, and T. cruzi-infected triatomines in the period 2000-2022, a systematic review was conducted following the PRISMA guidelines. Fifty-five original research articles retrieved from PubMed and ScienceDirect were selected; forty-four papers reported 1-26,946 transcripts, and twenty-one studies described 1-2603 peptides/proteins.

Immunopathological Mechanisms Underlying Cardiac Damage in Chagas Disease.

In Chagas disease, the mechanisms involved in cardiac damage are an active field of study. The factors underlying the evolution of lesions following infection by Trypanosoma cruzi and, in some cases, the persistence of its antigens and the host response, with the ensuing development of clinically observable cardiac damage, are analyzed in this review.

Parasitemia and Differential Tissue Tropism in Mice Infected with Trypanosoma cruzi Isolates Obtained from Meccus phyllosoma in the State of Oaxaca, Mexico.

Trypanosoma cruzi is a parasite transmitted by the feces of triatomines. Many triatomine species are found in Mexico, and various T. cruzi variants have been isolated from these species, each showing very different virulence and cell tropism. The isolates were obtained from Meccus phyllosoma specimens in three localities in the state of Oaxaca, Mexico: Tehuantitla, Vixhana, and Guichivere. The virulence of each isolate was assessed by quantifying parasitemia, survival, and histopathologic findings. The lineage of each isolate was identified using the mini-exon gene. The expression of the tssa gene during infection was detected in the heart, esophagus, gastrocnemius, and brain. Our results show that the maximum post-infection parasitemia was higher for the Tehuantitla isolate. On genotyping, all isolates were identified as T. cruzi I. The amastigotes in the heart and gastrocnemius were verified for all isolates, but in the brain only for Tehuantitla and Vixhana. The tssa expression allowed us to detect T. cruzi isolates, for Tehuantitla, predominantly in the heart. For Vixhana, a higher tssa expression was detected in gastrocnemius, and for Guichivere, it was higher in the esophagus. Results show that virulence, tropism, and tssa expression can vary, even when the isolates are derived from the same vector species, in the same region, and at similar altitudes.

Response to Infection by Trypanosoma cruzi in a Murine Model.

Cardiopathy is a common, irreversible manifestation of the chronic phase of Chagas disease; however, there is controversy as to how the causes for progression from the acute to the chronic phase are defined. In this work, the presence of the parasite is correlated with the occurrence of cell infiltration and fibrosis in cardiac tissues, as well as IgG detection and disease progression in a murine model. Fifty CD1 mice were infected intraperitoneally with Trypanosoma cruzi, while 30 control were administered with saline solution. Parasitemia levels were determined, and IgG titers were quantified by ELISA. At different times, randomly selected mice were euthanized, and the heart was recovered. Cardiac tissue slides were stained with HE and Masson trichrome stain. A significant increase in parasitemia levels was observed after 15 days post-infection (dpi), with a maximum of 4.1 × 106 parasites on 33 dpi, ending on 43 dpi; amastigote nests were observed on 15-62 dpi. Histological analysis revealed lymphocytic infiltration and fibrotic lesions from 8 dpi until the end of the study, on 100 dpi. The presence of plasma cells in the myocardium observed on 40-60 dpi, accompanied by seropositivity to ELISA on 40-100 dpi, was regarded as the hallmark of the transition phase. Meanwhile, the chronic phase, characterized by the absence of amastigotes, presence of cell infiltration, fibrotic lesions, and seropositivity, started on 62 dpi. A strong correlation between parasitemia and the presence of amastigote nests was found (r 2 = 0.930), while correlation between the presence of fibrosis and of amastigote nests was weak (r 2 = 0.306), and that between fibrosis and lymphocyte infiltration on 100 dpi was strong (r 2 = 0.899). The murine model is suitable to study Chagas disease, since it can reproduce the chronic and acute phases of the human disease. The acute phase was determined to occur on 1-60 dpi, while the chronic phase starts on 62 dpi, and fibrotic damage is a consequence of the continuous inflammatory infiltration; on the other hand, fibrosis was determined to start on the acute phase, being more apparent in the chronic phase, when Chagas disease-related cardiopathy is induced.

Coinfection by Trypanosoma cruzi and a fungal pathogen increases survival of Chagasic bugs: advice against a fungal control strategy.

Triatomine bugs carry the parasitic protozoa Trypanosoma cruzi, the causal agent of Chagas disease. It is known that both the parasite and entomopathogenic fungi can decrease bug survival, but the combined effect of both pathogens is not known, which is relevant for biological control purposes. Herein, the survival of the triatomine Meccus pallidipennis (Stal, 1872) was compared when it was coinfected with the fungus Metarhizium anisopliae (Metschnikoff) and T. cruzi, and when both pathogens acted separately. The immune response of the insect was also studied, using phenoloxidase activity in the bug gut and hemolymph, to understand our survival results. Contrary to expectations, triatomine survival was higher in multiple than in single challenges, even though the immune response was lower in cases of multiple infection. We postulate that T. cruzi exerts a protective effect and/or that the insect reduced the resources allocated to defend itself against both pathogens. Based on the present results, the use of M. anisopliae as a control agent should be re-considered.

Activity of the prophenoloxidase system and survival of triatomines infected with different Trypanosoma cruzi strains under different temperatures: understanding Chagas disease in the face of climate change.

BACKGROUND: Little is known about how human disease vectors will modify their life history patterns and survival capacity as a result of climate change. One case is that of Chagas disease, which has triatomine bugs and Trypanosoma cruzi as vectors and parasite, respectively. This work aimed to determine: (i) the activity of the prophenoloxidase system (prophenoloxidase and phenoloxidase activity, two indicators of immune ability) in three intestine regions (anterior midgut, posterior midgutand rectum) of the triatomine bug Meccus pallidipennis under three temperature conditions (20 °C, 30 °C and 34 °C) against two T. cruzi strains [ITRI/MX/14/CHIL (Chilpancingo) and ITRI/MX/12/MOR (Morelos)], and (ii) whether vector survival varies under these three temperatures after infection by these T. cruzi strains. RESULTS: Our results indicate that prophenoloxidase activity was lower at higher temperatures, that the level of prophenoloxidase activity elicited by each strain was different (higher in Chilpancingo than in Morelos strains), and that prophenoloxidase activity was more intense in the anterior midgut than in the posterior midgut or rectum. Survival rates were lower in insects maintained at higher temperatures and infected by Chilpancingo strains. CONCLUSIONS: These results indicate that climate change could lead to lower prophenoloxidase activity and survival rates in triatomines when infected with different T. cruzi strains, which could reduce the vector capacity of M. pallidipennis.

Identification of O-Glcnacylated Proteins in Trypanosoma cruzi.

Originally an anthropozoonosis in the Americas, Chagas disease has spread from its previous borders through migration. It is caused by the protozoan Trypanosoma cruzi. Differences in disease severity have been attributed to a natural pleomorphism in T. cruzi. Several post-translational modifications (PTMs) have been studied in T. cruzi, but to date no work has focused on O-GlcNAcylation, a highly conserved monosaccharide-PTM of serine and threonine residues mainly found in nucleus, cytoplasm, and mitochondrion proteins. O-GlcNAcylation is thought to regulate protein function analogously to protein phosphorylation; indeed, crosstalk between both PTMs allows the cell to regulate its functions in response to nutrient levels and stress. Herein, we demonstrate O-GlcNAcylation in T. cruzi epimastigotes by three methods: by using specific antibodies against the modification in lysates and whole parasites, by click chemistry labeling, and by proteomics. In total, 1,271 putative O-GlcNAcylated proteins and six modification sequences were identified by mass spectrometry (data available via ProteomeXchange, ID PXD010285). Most of these proteins have structural and metabolic functions that are essential for parasite survival and evolution. Furthermore, O-GlcNAcylation pattern variations were observed by antibody detection under glucose deprivation and heat stress conditions, supporting their possible role in the adaptive response. Given the numerous biological processes in which O-GlcNAcylated proteins participate, its identification in T. cruzi proteins opens a new research field in the biology of Trypanosomatids, improve our understanding of infection processes and may allow us to identify new therapeutic targets.

Effects of Trypanosoma cruzi on the phenoloxidase and prophenoloxidase activity in the vector Meccus pallidipennis (Hemiptera: Reduviidae).

BACKGROUND: Triatomine insects are vectors of Trypanosoma cruzi, the causal agent of Chagas disease. The insect-parasite interaction has been studied in relation to the transmission and prevalence of this disease. For most triatomines, however, several crucial aspects of the insect immune response are still unknown. For example, only for Rhodnius prolixus and Triatoma infestans has the activity of phenoloxidase (PO) and its zymogen prophenoloxidase (proPO) been reported in relation to the hemolymph and anterior midgut (AM). The aim of this study was to gain insight into the immune response to T. cruzi infection of an important triatomine in Mexico, Meccus pallidipennis. METHODS: Parasites were quantified in the rectal contents of infected M. pallidipennis groups. We examined some key factors in disease transmission, including the systemic (hemolymph) and local (gut) immune response. RESULTS: Parasites were present in the rectal contents at 4 days post-infection (pi) and reached their maximum density on day 7 pi. At 7 and 9 days pi mainly metacyclic trypomastigotes occurred. Compared to the control, the infected insects exhibited diminished PO activity in the hemolymph on days 9, 16 and 20 pi, and in the AM only on day 9. Additionally, infected insects displayed lower proPO activity in the hemolymph on day 1, but greater activity in the AM on day 28. CONCLUSIONS: The parasite strain originating from M. pallidipennis rapidly colonized the rectum of nymphs of this triatomine and developed high numbers of metacyclic trypomastigotes. Neither the changes of concentrations of PO and proPO in the hemolymph nor in the AM correlated with the changes in the population of T. cruzi.

Bacterial symbionts in human blood-feeding arthropods: Patterns, general mechanisms and effects of global ecological changes.

Due to their high impact on public health, human blood-feeding arthropods are one of the most relevant animal groups. Bacterial symbionts have been long known to play a role in the metabolism, and reproduction of these arthropod vectors. Nowadays, we have a more complete picture of their functions, acknowledging the wide influence of bacterial symbionts on processes ranging from the immune response of the arthropod host to the possible establishment of pathogens and parasites. One or two primary symbiont species have been found to co-evolve along with their host in each taxon (being ticks an exception), leading to various kinds of symbiosis, mostly mutualistic in nature. Moreover, several secondary symbiont species are shared by all arthropod groups. With respect to gut microbiota, several bacterial symbionts genera are hosted in common, indicating that these bacterial groups are prone to invade several hematophagous arthropod species feeding on humans. The main mechanisms underlying bacterium-arthropod symbiosis are discussed, highlighting that even primary symbionts elicit an immune response from the host. Bacterial groups in the gut microbiota play a key role in immune homeostasis, and in some cases symbiont bacteria could be competing directly or indirectly with pathogens and parasites. Finally, the effects climate change, great human migrations, and the increasingly frequent interactions of wild and domestic animal species are analyzed, along with their implications on microbiota alteration and their possible impacts on public health and the control of pathogens and parasites harbored in arthropod vectors of human parasites and pathogens.

Th-17 cytokines are associated with severity of Trypanosoma cruzi chronic infection in pediatric patients from endemic areas of Mexico.

In Chagas disease the clinical, acute and chronic manifestations are the result of the interaction between the parasite and the host factors. The balance between inflammatory and anti-inflammatory immune responses is essential for the increase or resolution of the manifestations in individuals infected with T. cruzi. To identify if children with chronic Chagas disease and heart injury is related with non-regulated Th1, Th2 and Th17 responses. We included 31 children with T. cruzi confirmed chronic infection from endemic areas of Mexico. Subsequently, they were separated according to their ECHO and ECG results into three groups according to the severity of cardiac involvement. Circulating Th1, Th2 and Th17 cytokine profiles were performed by Luminex assays and the results were analyzed by bivariate and multivariable analysis. Patients were classified in asymptomatic chronic (group 1, N=12); individuals with IRBBB in ECG and incipient lesions in ECHO (Group 2, N=8) and Patients with severe chronic symptomatic disease (Group 3, N=11). The analysis of immune mediators revealed that patients with severe cardiac manifestations had significant higher levels (p <0.05) of Th17 related cytokines including IL-17 and IL-6 as well as IFN-γ and IL-2. Also patients with severe cardiomyopathy exhibit increased levels of IL-13 (p <0.05) after multivariate analysis. High levels of Th17 related cytokines including IL-17, IFN-γ, IL-6 and IL-2 and pro-fibrotic factors such as IL-13 could be associated to the severity of cardiac involvement in children with chronic T. cruzi infection. These cytokines could be useful as indicators for the early identification of cardiac damage associated to the T. cruzi infection.

Chagas Disease in Mexico: Report of 14 Cases of Chagasic Cardiomyopathy in Children.

Chagas disease is a parasitic infection mainly found in Latin America; it is transmitted by a triatomine, also known as assassin bug or kissing bug. In humans, the parasite causes mostly cardiac disorders. Two-thirds of the Mexican territory are regarded as risk areas for vector transmission of Trypanosoma cruzi, the causal agent. The parasite can be found as a blood-borne trypomastigote or as an intracellular amastigote. The progression and severity of lesions could be due to frequent reinfections or to infection by highly virulent strains. A total of 3,327 individuals younger than 18 years old, living in risk areas for this disease in the rural setting of the States of Queretaro, San Luis Potosi, and Veracruz, underwent a seroepidemiological study. Among them, 37 subjects were seropositive for T. cruzi, and were studied to look for signs of cardiac pathology, which has only been reported in adults. A clinical record was prepared for all included individuals, and electrocardiography (ECG) and echocardiography (ECHO) studies were performed; 25 cases showed lesions compatible with the onset of Chagas cardiomyopathy. The other 12 patients showed either normal ECG and ECHO data or showed abnormal parameters that were not regarded as significant. Lesions found in the onset of Chagas cardiomyopathy in children are herein reported, along with 14 cases of cardiac pathology compatible with Chagas disease. Our results indicate that patients younger than 18 years can show a cardiac pathology similar to that observed in adults.

Enfermedad de Chagas en México / Chagas disease in Mexico

Resumen México es un país endémico para la enfermedad de Chagas, donde dos terceras partes del territorio pueden ser consideradas en riesgo de transmisión vectorial, es decir que 1'100,000 individuos podrían estar infectados con Trypanosoma cruzi y 29'500,000 en riesgo de contraer la infección. En la morbimortalidad del padecimiento son importantes las características de la vivienda, condiciones biológicas, ambientales y factores socioculturales. El tamizaje en bancos de sangre, a la fecha, es de observancia obligatoria con una cobertura mayor al 92%. El diagnóstico no se establece frecuentemente debido al desconocimiento de la enfermedad por parte del personal de salud y de la población. La fase aguda generalmente pasa desapercibida y en la crónica, la patología se presenta principalmente en el corazón, con evolución lenta. La patogénesis de la miocardiopatía crónica es muy compleja y se presentan lesiones con mayor frecuencia en el sistema nervioso autónomo y miocardio, lo que genera trastornos en la conductibilidad y contractilidad del órgano. Se describen los principales mecanismos patogénicos implicados en el desarrollo de la enfermedad.

Abstract Mexico is a country endemic for Chagas disease in which two thirds of the territory can be considered at risk of vector-borne infection. This means that 1.1 million people could be infected with Trypanosoma cruzi and 29.5 million at risk of infection. Dwelling characteristics of poverty in these rural areas linked with biological conditions, lifestyle, environmental and sociocultural factors are important in the morbidity and mortality of the disease. Nowadays, the screening for the parasite is mandatory and at least 92% of blood banks are covered. The inadequate knowledge of the disease by the health personnel and the population limits the possibility of the diagnosis. The acute phase of the disease courses undetected. The main affected organ in Chagas disease is the heart, with a slow evolution; the pathogenesis of chronic cardiomyopathy is complex and lesions occur mainly in the autonomic nervous system and myocardium leading to disturbances in the conductivity and contractility of the organ. The main pathogenic mechanisms involved in the development of the disease are described.

Survival and immune response of the Chagas vector Meccus pallidipennis (Hemiptera: Reduviidae) against two entomopathogenic fungi, Metarhizium anisopliae and Isaria fumosorosea.

BACKGROUND: Chagas disease is a key health problem in Latin America and is caused and transmitted by Trypanosoma cruzi and triatomine bugs, respectively. Control of triatomines has largely relied on the use pyrethroids, which has proved to be ineffective in the long term. Alternatively, the use of entomopathogenic fungi has been implemented to control triatomine bugs. These fungi are highly efficient as they induce a reduction in immune response on insects. Meccus pallidipennis is the main triatomine vector of Chagas disease in Mexico. In this work we investigated the effects of two entomopathogenic fungi, Metarhizium anisopliae and Isaria fumosorosea, on M. pallidipennis nymphs in terms of insect survival and immune response. METHODS: We had an infected and a control group for each fungal species and assessed: a) insect survival during 30 days; and, b) phenoloxidase (PO) and prophenoloxidase (proPO; two key traits in insect immune response) at 24, 48, 96 and 144 h. For survival we used Kaplan-Meier survival analysis while for immune response we used factorial, repeated-measures ANOVA for each fungal species. RESULTS: Animals treated with M. anisopliae died sooner than animals treated with I. fumosorosea. Infected animals showed lower PO and proPO values than sham individuals, with a clear decrease in these parameters at 24 h with no further changes after this time. CONCLUSIONS: Our study widens the possibility of entomopathogenic fungi being used for triatomine control. The negative effect on PO and proPO seems mediated by a down-regulation of the triatomine immune response.

[Identification of immunodominant components of an isolate of Trypanosoma cruzi by immunoblot and its standardization for diagnostic purposes]. / Identificación de componentes inmunodominantes de un aislado de Trypanosoma cruzi por inmunoblot y su estandarización con fines diagnósticos.

INTRODUCTION: Conventional serology was used for the detection of Trypanosoma cruzi infection, with diverse sensitivity and specificity results. Due to the number of samples with doubtful results, it is necessary to develop additional confirmation tests such as the immunoblot. OBJECTIVE: The aim of this study was identify major immunogenic proteins of T. cruzi isolate and establish criteria for immunoblot positivity with diagnostic purposes. METHODS: Immunoblot initial standardization was performed, determining optimal concentrations of antigen, serum, and second antibody. Thirty-five positive and thirty negative sera were assayed to evaluate different criteria of positivity and determine which provides greater sensitivity and specificity. RESULTS: Immunoblot of T. cruzi positive sera shared a rich pattern of components with molecular weights between 10-250 kDa. Twelve components had a recognition rate higher than 50%, of which the polypeptides of 27, 32, 34, and 38 kDa were close to 100%. Of the positivity criteria evaluated, the recognition of the components of 27 and 32 kDa provided sensitivity and specificity of 100%. DISCUSSION: The Immunoblot is suitable for confirmation of infection by T. cruzi, so it is strongly recommended for confirmation and discrimination of discordant cases.

[Chagas disease in Mexico. Report of two acute cases]. / Presentación de dos casos de enfermedad de Chagas aguda en México.

Two cases of acute Chagas disease in schoolchildren of 6 and 13 years of age, both with the clinical features of Romaña's sign, regional lymphadenopathy, and fever, have a history of coexistence and the bite of the transmitter, and live in housing constructed with material considered at risk for infestation by the vector; i.e. roof and walls with palma/zacate (palm tree, grass leaves), dirt floor, and inadequate illumination and ventilation. The parasitological diagnosis of both cases was established by identification of trypomastigotes of Trypanosoma cruzi in blood smears and the parasite was isolated in one of them. Benznidazole treatment was administered according to the guidelines of the WHO/PAHO for this disease. The presence of acute Chagas disease in rural areas confirms the active transmission of the parasite, so surveillance and epidemiological controls should be applied. The importance of these cases is that T. cruzi infection is symptomatic in 5% of cases, which implies that a high percentage of cases of infection appear asymptomatic and are not being diagnosed in our country.

Evaluación de la función y sincronía de la contracción ventricular en pacientes con enfermedad de Chagas en estadio de latencia / Evaluation of the function and ventricular synchrony in patients with latency stage of Chagas' disease

OBJECTIVE: To compare the left ventricular function and the ventricular synchrony in patients with Chagas disease in latency stage respect to a control group. METHODS: We analyze a prospective, comparative, transversal and non randomized study of the left ventricular function (LVF) and the ventricular contraction synchronicity (VCS) in 36 subjects with positive serology for Chagas disease (18 males and 18 females), with mean of 15 +/- 5-years-old. The findings were compared with respect to 23 control volunteers (11 males and 12 females) with mean of 28 +/- 5-years-old. LVF and VCS were evaluated using equilibrium radionuclide angiography images (ERNA). The comparison of both Chagas and control populations was carried out by t Student test for independent samples, considering a statistically significant value of p < 0.05. RESULTS: The parameters of the ventricular function and the ventricular synchronicity in subjects with positive serology for Chagas disease were not statistically different with respect to the parameters of the control group. However, although they have a homogeneous contraction, the mean time of contraction for the right and the left ventricle is statistically smaller with respect to the control group. CONCLUSIONS: In clinically incipient stages of Chagas disease we do not found abnormalities in the ventricular function and the ventricular synchronicity. It's necessary to consider the follow up of the studied populations using indices for the identification of abnormalities of the autonomic nervous system.

Chagas disease as a cause of symptomatic chronic myocardopathy in Mexican children.

We report the first case series of children in Mexico living with symptomatic Chagas disease causing chronic myocardopathy. The findings suggest that children with Chagas disease may develop symptomatic chronic myocardopathy earlier than previously recognized. Our findings emphasize the importance of longitudinal cardiologic follow-up of all children identified with acute Chagas disease.In a cohort of 826 children from the state of Queretaro in Mexico, 11 were identified with positive serology (ELISA and IFI) for Chagas and were tested for electrocardiogram alterations and symptoms and signs. Four children had ECG alterations with 3 of these reporting signs and symptoms associated with the chronic phase of Chagas disease (27%; 95% CI: 6%-61%). The most common chronic symptom was chest pain, with one child also reporting dyspnea and tachycardia.

[Evaluation of the function and ventricular synchrony in patients with latency stage of Chagas' disease]. / Evaluación de la función y sincronía de la contracción ventricular en pacientes con enfermedad de Chagas en estadio de latencia.

OBJECTIVE: To compare the left ventricular function and the ventricular synchrony in patients with Chagas disease in latency stage respect to a control group. METHODS: We analyze a prospective, comparative, transversal and non randomized study of the left ventricular function (LVF) and the ventricular contraction synchronicity (VCS) in 36 subjects with positive serology for Chagas disease (18 males and 18 females), with mean of 15 +/- 5-years-old. The findings were compared with respect to 23 control volunteers (11 males and 12 females) with mean of 28 +/- 5-years-old. LVF and VCS were evaluated using equilibrium radionuclide angiography images (ERNA). The comparison of both Chagas and control populations was carried out by t Student test for independent samples, considering a statistically significant value of p < 0.05. RESULTS: The parameters of the ventricular function and the ventricular synchronicity in subjects with positive serology for Chagas disease were not statistically different with respect to the parameters of the control group. However, although they have a homogeneous contraction, the mean time of contraction for the right and the left ventricle is statistically smaller with respect to the control group. CONCLUSIONS: In clinically incipient stages of Chagas disease we do not found abnormalities in the ventricular function and the ventricular synchronicity. It's necessary to consider the follow up of the studied populations using indices for the identification of abnormalities of the autonomic nervous system.

Insecticide and community interventions to control Triatoma dimidiata in localities of the State of Veracruz, Mexico

Three different interventions to control Triatoma dimidiata in the State of Veracruz were implemented: X-1 = whole dwelling spraying, X-2 = middle wall spraying, X-3 = household cleaning. Cyfluthrin was sprayed 3 times with 8 month intervals. After each spraying, insects were collected and sent to the laboratory to be recorded and to determine genus and species of the adult triatomine bugs, and nymphs were counted. Trypanosoma cruzi presence was determined. With X-1, the infestation, colonization, and natural infection indexes were reduced to 0 percent in the 3 localities, with respect to t0. With X-2, the infestation index was reduced to 10 percent at t3 in 3 localities; the colonization index was reduced to 0 percent in only 1 locality at t3, and the natural infection index was reduced to 0 percent at t3. With X-3 the 3 indexes were not effectively reduced but they decreased with respect to the baseline study. Insecticide application to the whole dwelling is a more efficient intervention than its application to only the lower half of the walls and to the cleaning of houses.