Entomological surveillance of Chagas disease in the East of Minas Gerais region, Brazil

ABSTRACT Background: After decentralizing the actions of the Chagas Disease Control Program (CDCP) in Brazil, municipalities were now responsible for control measures against this endemic, supervised by the Regional Health Superintendencies (RHS). We aimed to evaluate the recent entomological surveillance of Chagas disease in the Regional Health Superintendence of Governador Valadares (RHS/GV) from 2014 to 2019. Methods: Triatomines captured by residents during entomological surveillance were sent to the reference laboratory, where the species and evolutionary stages were identified, place of capture, and presence of Trypanosoma cruzi. A database was created, and the following were calculated: the rate of infection by T. cruzi (overall rate and rate by species), monthly seasonality, spatial distribution of species, number of captures, and infected triatomines/health microregions. Results: We identified 1,708 insects; 1,506 (88.2%) were triatomines, most were adult instars (n=1,469), and few were nymphs (n=37). The identified species were Triatoma vitticeps, Panstrongylus megistus, Panstrongylus diasi, Rhodnius neglectus, and Panstrongylus geniculatus. The first three were most frequently captured and distributed throughout the study area. Most bugs were captured intradomicile (72.5%), mainly in the second semester, between September and November, with an average infection rate of 41.5% (predominantly T. vitticeps, 49.2%). All municipalities sent triatomines, especially in the microregions of Governador Valadares. Conclusions: These data reinforce the need and importance of improving Chagas disease control measures in the region to establish active and participatory entomological surveillance.

Ectonucleotidases from trypomastigotes from different sources and various genetic backgrounds of Trypanosoma cruzi potentiate their infectivity and host inflammation.

Distinct populations of Trypanosoma cruzi interact with mammalian cardiac muscle cells causing different inflammation patterns and low heart functionality. During T. cruzi infection, the extracellular ATP is hydrolyzed to tri- and/or diphosphate nucleotides, based on the infectivity, virulence, and regulation of the inflammatory response. T. cruzi carries out this hydrolysis through the T. cruzi ectonucleotidase, NTPDase-1 (TcNTPDase-1). This study aimed to evaluate the role of TcNTPDase-1 in culture rich in metacyclic trypomastigote forms (MT) and cell culture-derived trypomastigote forms (CT) from Colombiana (discrete typing unit - DTU I), VL-10 (DTU II), and CL (DTU VI) strains of T. cruzi. For this, we measured TcNTPDase-1 activity in suramin-treated and untreated parasites and infected J774 cells and C57BL/6 mice with suramin pre-treated parasites to assess parasitic and inflammatory cardiac profile in the acute phase of infection. Our data indicated a higher TcNTPDase-1 activity for ATP in culture rich in metacyclic trypomastigote forms from Colombiana strain in comparison to those from VL-10 and CL strains. The cell culture-derived trypomastigote forms from CL strain presented higher capacity to hydrolyze ATP than those from Colombiana and VL-10 strains. Suramin inhibited ATP hydrolysis in all studied parasite forms and strains. Suramin pre-treated parasites reduced J774 cell infection and increased nitrite production in vitro. In vivo studies showed a reduction of inflammatory infiltrate in the cardiac tissues of animals infected with cell culture-derived trypomastigote forms from suramin pre-treated Colombiana strain. In conclusion, TcNTPDase-1 activity in trypomastigotes forms drives part of the biological characteristics observed in distinct DTUs and may induce cardiac pathogenesis during T. cruzi infection.

Evaluation of parasite and host genetics in two generations of a family with Chagas disease.

Chagas disease, caused by the protozoan Trypanosoma cruzi, is considered to be a multifactorial disease associated with host and parasite genetics, which influence clinical aspects of the disease and other host conditions. In order to understand better the evolution of the disease, this study intended to evaluation of parasite and host genetics in two generations of a family with Chagas disease from the Alto Paranaiba region, Minas Gerais, Brazil, comprising a mother and her five daughters. Several features were evaluated, including the characterization of T. cruzi directly from the blood of patients, host polymorphisms of genes related to cardiomyopathy (TNF, WISP1, CCR5, and TGF-ß1) and clinical aspects of the patients. To verify the intraspecific variability of the parasite, the characterization was done directly from human blood using the PCR-LSSP technique and analyzed based on Dice coefficient and unweighted pair group analysis (UPGMA). The host polymorphism was evaluated by PCR-RFLP. The global results showed low variability of the parasites characterized from blood of patients, through Shannon index (0.492) and mean heterozygosity value per locus (0.322). All six patients presented the same genetic polymorphism profile for TNF, WISP1, and TGF-ß1, and only one patient was homozygous to CCR5, which suggests that there is no association between the clinical aspects of the patients and their genetic profiles. In conclusion, the findings confirm that the understanding of the clinical evolution of Chagas disease goes beyond the genetic aspects of the parasite and the host.

Increased Body Exposure to New Anti-Trypanosomal Through Nanoencapsulation.

Lychnopholide, a lipophilic sesquiterpene lactone, is efficacious in mice at the acute and chronic phases of Chagas disease. Conventional poly-ε-caprolactone (PCL) and long-circulating poly(D,L-lactide)-block-polyethylene glycol (PLA-PEG) nanocapsules containing lychnopholide were developed and characterized. Lychnopholide presented high association efficiency (>90%) with the nanocapsules. A new, fast and simple HPLC-UV-based bioanalytical method was developed, validated in mouse plasma and applied to lychnopholide quantification in in vitro release kinetics and pharmacokinetics. The nanocapsules had mean hydrodynamic diameters in the range of 100-250 nm, negative zeta potentials (-30 mV to -57 mV), with good physical stability under storage. Atomic force microscopy morphological analysis revealed spherical monodispersed particles and the absence of lychnopholide crystallization or aggregation. Association of lychnopholide to PLA-PEG nanocapsules resulted in a 16-fold increase in body exposure, a 26-fold increase in plasma half-life and a dramatic reduction of the lychnopholide plasma clearance (17-fold) in comparison with free lychnopholide. The improved pharmacokinetic profile of lychnopholide in long-circulating nanocapsules is in agreement with the previously reported improved efficacy observed in Trypanosoma cruzi-infected mice. The present lychnopholide intravenous dosage form showed great potential for further pre-clinical and clinical studies in Chagas disease and cancer therapies.

Experimental benznidazole treatment of Trypanosoma cruzi II strains isolated from children of the Jequitinhonha Valley, Minas Gerais, Brazil, with Chagas disease

Trypanosoma cruzi strains from distinct geographic areas show differences in drug resistance and association between parasites genetic and treatment response has been observed. Considering that benznidazole (BZ) can reduce the parasite burden and tissues damage, even in not cured animals and individuals, the goal is to assess the drug response to BZ of T. cruzi II strains isolated from children of the Jequitinhonha Valley, state of Minas Gerais, Brazil, before treatment. Mice infected and treated with BZ in both phases of infection were compared with the untreated and evaluated by fresh blood examination, haemoculture, polymerase chain reaction, conventional (ELISA) and non-conventional (FC-ALTA) serologies. In mice treated in the acute phase, a significant decrease in parasitaemia was observed for all strains. Positive parasitological and/or serological tests in animals treated during the acute and chronic (95.1-100%) phases showed that most of the strains were BZ resistant. However, beneficial effect was demonstrated because significant reduction (p < 0.05%) and/or suppression of parasitaemia was observed in mice infected with all strains (acute phase), associated to reduction/elimination of inflammation and fibrosis for two/eight strains. BZ offered some benefit, even in not cured animals, what suggest that BZ use may be recommended at least for recent chronic infection of the studied region.

Evaluation of the Chagas Disease Control Program in Açucena Municipality, Rio Doce Valley, State of Minas Gerais, Brazil

Introduction Açucena Municipality, Rio Doce Valley, State of Minas Gerais, Brazil temporarily (2001-2005) interrupted epidemiological surveillance for Chagas disease. The objective of this work was to evaluate the Chagas Disease Control Program (CDCP) in Açucena and to offer suggestions for improving local epidemiological surveillance. Methods This study was conducted in three phases: I) a serological investigation of schoolchildren aged 5 to 15 years using an enzyme-linked immunosorbent assay (ELISA) test performed on blood collected on filter paper followed by ELISA, indirect immunofluorescence (IIF) and indirect hemaglutination (IHA) on venous blood for borderline cases and those in the gray zone of reactivity; II) vector evaluation using the data obtained by local health agents during 2006-2010; and III) examination by ELISA, IIF and IHA of serum samples from the inhabitants of houses where infected Triatoma vitticeps was found and evaluation of their knowledge about Chagas disease. Results Five individuals had inconclusive results in the ELISA screening but were seronegative for Chagas disease. The triatomine evaluation revealed the presence of three species: Triatoma vitticeps, Panstrongylus megistus and Panstrongylus diasi. Triatoma vitticeps was the most prevalent and widespread, with a higher (67%) index of Trypanosoma cruzi flagellates and evidence of colonization. Most of the inhabitants of the infested houses recognized triatomines and had basic knowledge about Chagas disease. Conclusions Although T. vitticeps is not clearly associated with Chagas disease transmission, these results highlight the importance of maintaining CDCP in endemic areas and the need for greater emphasis on epidemiological surveillance, especially in areas with important vectorial changes or that have been modified by human intervention. .

A serological, parasitological and clinical evaluation of untreated Chagas disease patients and those treated with benznidazole before and thirteen years after intervention

The etiological treatment of Chagas disease is recommended for all patients with acute or recent chronic infection, but controversies remain regarding the benefit of chemotherapy and interpretations of the parasitological cure after etiological treatment. This study compares the laboratory and clinical evaluations of Chagas disease patients who were diagnosed 13 years earlier. Fifty-eight Chagas disease patients (29 treated with benznidazole and 29 untreated) were matched at the time of treatment based on several variables. Conventional serology revealed the absence of seroconversion in all patients. However, lower serological titres were verified in the treated group, primarily among patients who had the indeterminate form of the disease. Haemoculture performed 13 years after the intervention was positive for 6.9% and 27.6% of the treated and untreated patients, respectively. Polymerase chain reaction tests were positive for 44.8% and 13.8% of the treated and untreated patients, respectively. Patients who presented with the indeterminate form of the disease at the beginning of the study exhibited less clinical progression (17.4%) compared with the untreated group (56.5%). Therefore, this global analysis revealed that etiological treatment with benznidazole may benefit patients with respect to the clinical progression of Chagas disease and the prognosis, particularly when administered to patients with the indeterminate form of the disease.

Molecular and biological characterization of Trypanosoma cruzi strains isolated from children from Jequitinhonha Valley, State of Minas Gerais, Brazil

Introduction The biological diversity of Trypanosoma cruzi strains plays an important role in the clinical and epidemiological features of Chagas disease. Methods Eight T. cruzi strains isolated from children living in a Chagas disease vector-controlled area of Jequitinhonha Valley, State of Minas Gerais, Brazil, were genetically and biologically characterized. Results The characterizations demonstrated that all of the strains belonged to T. cruzi II, and showed high infectivity and a variable mean maximum peak of parasitemia. Six strains displayed low parasitemia, and two displayed moderate parasitemia. Later peaks of parasitemia and a predominance of intermediate and large trypomastigotes in all T. cruzi strains were observed. The mean pre-patent period was relatively short (4.2±0.25 to 13.7±3.08 days), whereas the patent period ranged from 3.3±1.08 to 34.5±3.52 days. Mortality was observed only in animals infected with strain 806 (62.5%). Histopathological analysis of the heart showed that strains 501 and 806 caused inflammation, but fibrosis was observed only in animals infected with strain 806. Conclusions The results indicate the presence of an association between the biological behavior in mice and the genetic characteristics of the parasites. The study also confirmed general data from Brazil where T. cruzi II lineage is the most prevalent in the domiciliary cycle and generally has low virulence, with some strains capable of inducing inflammatory processes and fibrosis. .

In-house ELISA method to analyze anti-Trypanosoma cruzi IgG reactivity for differential diagnosis and evaluation of Chagas disease morbidity / Método de ELISA in-house na análise da reatividade de IgG anti-Trypanosoma cruzi para o diagnóstico diferencial e avaliação da morbidade da doença de Chagas

INTRODUCTION: The goal was to develop an in-house serological method with high specificity and sensitivity for diagnosis and monitoring of Chagas disease morbidity. METHODS: With this purpose, the reactivities of anti-T. cruzi IgG and subclasses were tested in successive serum dilutions of patients from Berilo municipality, Jequitinhonha Valley, Minas Gerais, Brazil. The performance of the in-house ELISA was also evaluated in samples from other relevant infectious diseases, including HIV, hepatitis C (HCV), syphilis (SYP), visceral leishmaniasis (VL), and American tegumentary leishmaniasis (ATL), and noninfected controls (NI). Further analysis was performed to evaluate the applicability of this in-house methodology for monitoring Chagas disease morbidity into three groups of patients: indeterminate (IND), cardiac (CARD), and digestive/mixed (DIG/Mix), based on their clinical status. RESULTS: The analysis of total IgG reactivity at serum dilution 1:40 was an excellent approach to Chagas disease diagnosis (100 percent sensitivity and specificity). The analysis of IgG subclasses showed cross-reactivity, mainly with NI, VL, and ATL, at all selected serum dilutions. Based on the data analysis, the IND group displayed higher IgG3 levels and the DIG/Mix group presented higher levels of total IgG as compared with the IND and CARD groups. CONCLUSIONS: These findings demonstrated that methodology presents promising applicability in the analysis of anti-T. cruzi IgG reactivity for the differential diagnosis and evaluation of Chagas disease morbidity.

INTRODUÇÃO: O objetivo foi desenvolver um método sorológico in-house de alta especificidade e sensibilidade para diagnosticar e monitorar a morbidade da doença de Chagas. MÉTODOS: Para tal, a reatividade sorológica de IgG e subclasses foi testada em soros de pacientes chagásicos de Berilo, Vale do Jequitinhonha/MG/Brasil. A reatividade sorológica foi também avaliada em amostras de pacientes com outras doenças infecto-contagiosas relevantes, incluindo o HIV, vírus da hepatite C (VHC), sífilis (SYP), leishmaniose visceral (LV), leishmaniose tegumentar americana (LTA) e controles não infectados (NI) para verificar o desempenho do método. Outras análises foram feitas para avaliar a aplicabilidade desta metodologia no monitoramento da morbidade da doença de Chagas. Com este propósito os pacientes com doença de Chagas foram anteriormente classificados em três grupos: indeterminados (IND), cardíacos (CARD) e digestivos/mistos (DIG/Mis) conforme seu estado clínico. RESULTADOS: A análise da reatividade sorológica de IgG total na diluição 1:40 mostrou ser uma abordagem importante no diagnóstico da doença de Chagas (100 por cento de sensibilidade e especificidade e ausência de reação cruzada com as demais infecções). A análise das subclasses de IgG mostrou reação cruzada principalmente com NI, LV e LTA em todas as diluições. O grupo IND apresentou a maior reatividade para IgG3 e o grupo DIG/Mis apresentou nível mais elevado de IgG se comparados aos grupos IND e CARD. CONCLUSÕES: Estes achados demonstram que o método de ELISA in-house apresenta uma promissora aplicabilidade no diagnóstico diferencial e na avaliação da morbidade da doença de Chagas.

Expression profile and subcellular localization of HslV, the proteasome related protease from Trypanosoma cruzi.

Trypanosoma cruzi is a rare example of an eukaryote that has genes for two threonine proteases: HslVU complex and 20S proteasome. HslVU is an ATP-dependent protease consisting of two multimeric components: the HslU ATPase and the HslV peptidase. In this study, we expressed and obtained specific antibodies to HslU and HslV recombinant proteins and demonstrated the interaction between HslU/HslV by coimmunoprecipitation. To evaluate the intracellular distribution of HslV in T. cruzi we used an immunofluorescence assay and ultrastructural localization by transmission electron microscopy. Both techniques demonstrated that HslV was localized in the kinetoplast of epimastigotes. We also analyzed the HslV/20S proteasome co-expression in Y, Berenice 62 (Be-62) and Berenice 78 (Be-78) T. cruzi strains. Our results showed that HslV and 20S proteasome are differently expressed in these strains. To investigate whether a proteasome inhibitor could modulate HslV and proteasome expressions, epimastigotes from T. cruzi were grown in the presence of PSI, a classical proteasome inhibitor. This result showed that while the level of expression of HslV/20S proteasome is not affected in Be-78 strain, in Y and Be-62 strains the presence of PSI induced a significantly increase in Hslv/20S proteasome expression. Together, these results suggest the coexistence of the protease HslVU and 20S proteasome in T. cruzi, reinforcing the hypothesis that non-lysosomal degradation pathways have an important role in T. cruzi biology.

Hematological alterations during experimental canine infection by Trypanosoma cruzi / Alterações hematológicas durante a infecção canina experimental por Trypanosoma cruzi

To confirm that Beagle dogs are a good experimental model for Chagas disease, we evaluated hematological alterations during the acute and chronic phases in Beagle dogs infected with the Y, Berenice-78 (Be-78) and ABC strains of Trypanosoma cruzi, correlating clinical signs with the parasitemia curve. We demonstrate that the acute phase of infection was marked by lethargy and loss of appetite. Simultaneously, we observed anemia, leukocytosis and lymphocytosis. Also,we describe hematological alterations and clinical signs that were positively correlated with the parasitemia during the experimental infection with the three strains of T.cruzi, and demonstrate that experimental infection of Beagle is a trustworthy model for Chagas disease.

Para confirmar que cães Beagle são um bom modelo para doença de Chagas, foram avaliadas as alterações hematológicas durante as fases aguda e crônica em cães Beagle infectados com as cepas Y, Berenice-78 (Be-78) e ABC de Trypanosomacruzi, correlacionando os sinais clínicos com a curva de parasitemia. Foi demonstrado que a fase aguda da infecção foi marcada por letargia e perda de apetite. Simultaneamente, observou-se anemia, leucocitose e linfocitose. Ainda, foram descritas alterações hematológicas e sinais clínicos positivamente correlacionados com a parasitemia durante a infecção experimental com as três cepas de T.cruzi estudadas, demonstrando que a infecção em cães Beagle constitui um modelo fidedigno para a doença de Chagas.

Clinical and laboratory status of patients with chronic Chagas disease living in a vector-controlled area in Minas Gerais, Brazil, before and nine years after aetiological treatment

Twenty-eight Chagas disease patients (CD), 22 with the indeterminate clinical form (IND) and six with the cardiac or digestive form (CARD/DIG), were treated with benznidazole and underwent clinical and laboratorial analysis before (IND and CARD/DIG) and nine years after [patients after treatment (CDt), patients with the indeterminate clinical form at treatment onset (INDt) and with the cardiac or digestive form at treatment onset (CARD/DIGt)] treatment. The data demonstrate that 82.1 percent of CDt patients (23/28) remained clinically stable and 95.4 percent of the INDt (21/22) and 33.3 percent of the CARD/DIGt (2/6) patients showed unaltered physical and laboratorial examinations. The clinical evolution rate was 2 percent/year and was especially low in INDt patients (0.5 percent/year) relative to CARD/DIGt patients (7.4 percent/year). Positive haemoculture in treated patients was observed in 7.1 percent of the cases. None of the INDt (0/21) and 33.3 percent of the CARD/DIGt (2/6) patients displayed positive cultures. The PCR presented a positive rate significantly higher (85.2 percent, 23/27) than haemoculture and two samples from the same patient revealed the same result 57.7 percent of the patients. Conventional serology-ELISA on 16 paired samples remained positive in all individuals. Semi-quantitative ELISA highlighted significant decreases in reactivity, particularly in INDt relative to IND. Non-conventional serology-FC-ALTA-IgG, after treatment, showed positive results in all sera and 22 paired samples examined at seven and nine years after treatment, demonstrated significantly lower reactivity, particularly in INDt patients. This study was retrospective in nature, had a low number of samples and lacked an intrinsic control group, but the data corroborate other results found in the literature. The data also demonstrate that, even though a cure has not been detected in the none-treated patients, the benefits for clinical evolution ...

Entomological surveillance of Chagas disease in Berilo municipality, Jequitinhonha Valley, State of Minas Gerais, Brazil / Vigilância Entomológica da doença de Chagas no município de Berilo, Vale do Jequitinhonha, Estado de Minas Gerais, Brasil

This study aimed to evaluate the Chagas Disease Control Program which has operated since 1982 in the municipality of Berilo in the Jequitinhonha Valley, Minas Gerais, Brazil, based on evaluation of 5,242 domiciliary units (DUs) and 7,807 outbuildings over an eight-year period of epidemiological surveillance implanted in 1997. A total of 391 triatomines (280 Panstrongylus megistus and 111 Triatoma pseudomaculata) were captured, indicating the continued predominance of the former species. However, Triatoma pseudomaculata is clearly becoming more important in this region, with intradomiciliary colonies being detected in recent years. Entomological parameters, such as dispersion (17 percent) and intradomiciliary infestation (0.15 percent) indices, are compatible with the results of the epidemiological surveillance. The majority of DUs were of construction type A (plaster over bricks) or C (plaster over adobe). Twenty-five percent of the inhabitants of the DUs infested by triatomines were reactive in ELISA, IHA and IIF tests for Trypanosoma cruzi antigens.

O objetivo deste estudo foi avaliar o Programa de Controle de doença de Chagas instalado desde 1982 no município de Berilo, Vale do Jequitinhonha, MG, Brasil, baseado na avaliação de 5.242 unidades domiciliares e 7.807 anexos após oito anos de implantação da vigilância epidemiológica que ocorreu em 1997. Um total de 391 triatomíneos (280 Panstrongylus megistus e 111 Triatoma pseudomaculata) foram capturados, indicando o contínuo predomínio da primeira espécie. No entanto, Triatoma pseudomaculata está claramente se tornando mais importante nesta região, com colônias intradomiciliares sendo detectadas recentemente. Parâmetros entomológicos, como os índices de dispersão (17 por cento) e infestação intradomiciliar (0,15 por cento), são compatíveis com a fase de vigilância epidemiológica. A maioria das UDs apresenta padrão de construção tipo A (tijolo com reboco) e C (adobe com reboco). Dentre os habitantes das unidades domiciliares infestadas por triatomíneos, 25 por cento apresentavam testes reativos na ELISA, HAI e IFI para antígenos de Trypanosoma cruzi.

Development of chronic cardiomyopathy in canine Chagas disease correlates with high IFN-gamma, TNF-alpha, and low IL-10 production during the acute infection phase.

When infected with Trypanosoma cruzi, Beagle dogs develop symptoms similar to those of Chagas disease in human beings, and could be an important experimental model for a better understanding of the immunopathogenic mechanisms involved in chronic chagasic infection. This study evaluates IL-10, IFN-gamma and TNF-alpha production in the sera, culture supernatant, heart and cervical lymph nodes and their correlation with cardiomegaly, cardiac inflammation and fibrosis in Beagle dogs infected with T. cruzi. Pathological analysis showed severe splenomegaly, lymphadenopathy and myocarditis in all infected dogs during the acute phase of the disease, with cardiomegaly, inflammation and fibrosis observed in 83% of the animals infected by T. cruzi during the chronic phase. The data indicate that infected animals producing IL-10 in the heart during the chronic phase and showing high IL-10 production in the culture supernatant and serum during the acute phase had lower cardiac alterations (myocarditis, fibrosis and cardiomegaly) than those with high IFN-gamma and TNF-alpha levels. These animals produced low IL-10 levels in the culture supernatant and serum during the acute phase and did not produce IL-10 in the heart during the chronic phase of the disease. Our findings showed that Beagle dogs are a good model for studying the immunopathogenic mechanism of Chagas disease, since they reproduce the clinical and immunological findings described in chagasic patients. The data suggest that the development of the chronic cardiac form of the disease is related to a strong Th1 response during the acute phase of the disease, while the development of the indeterminate form results from a blend of Th1 and Th2 responses soon after infection, suggesting that the acute phase immune response is important for the genesis of chronic cardiac lesions.

Trypanosoma cruzi: effect of benznidazole therapy combined with the iron chelator desferrioxamine in infected mice.

Iron chelators have been employed in various studies aimed at evaluating the relationship between the iron status of the host and the development of infection. In the present study, the effects of benznidazole (BZ) therapy in combination with the iron chelator desferrioxamine (DFO) on the development of infection in mice inoculated with Trypanosoma cruzi Y strain have been investigated. Infected mice treated with DFO presented lower levels of parasitemia compared with infected untreated animals. Therapy with BZ for 21 days, with or without DFO, led to decreased parasitemia and reduced mortality, but BZ in combination with DFO treatment for 35 days (BZ/DFO-35) gave 0% mortality. All infected groups presented lower levels of iron in the liver, but serum iron concentrations were greater in DFO-35 and BZ/DFO-35, whereas hemoglobin levels were higher in BZ/DFO-35 and lower in DFO-35 compared with other treated groups. The percentage cure, determined from negative hemoculture and PCR results in animals that had survived for 60 days post-infection, was 18% for BZ and BZ/DFO-35, 42% for BZ combined with DFO for 21 days, and 67% for DFO-35. The results demonstrate that modification in iron stores increases BZ efficacy.

Trypanosoma cruzi: blood parasitism kinetics and their correlation with heart parasitism intensity during long-term infection of Beagle dogs

The goals of the present study were to evaluate the kinetics of blood parasitism by examination of fresh blood, blood culture (BC) and PCR assays and their correlation with heart parasitism during two years of infection in Beagle dogs inoculated with the Be-78, Y and ABC Trypanosoma cruzi strains. Our results showed that the parasite or its kDNA is easily detected during the acute phase in all infected animals. On the other hand, a reduced number of positive tests were verified during the chronic phase of the infection. The frequency of positive tests was correlated with T. cruzi strain. The percentage of positive BC and blood PCR performed in samples from animals inoculated with Be-78 and ABC strains were similar and significantly larger in relation to animals infected with the Y strain.Comparison of the positivity of PCR tests performed using blood and heart tissue samples obtained two years after infection showed two different patterns associated with the inoculated T. cruzi strain: (1) high PCR positivity for both blood and tissue was observed in animals infected with Be-78 or ABC strains; (2) lower and higher PCR positivity for the blood and tissue, respectively, was detected in animals infected with Y strains. These data suggest that the sensitivity of BC and blood PCR was T. cruzi strain dependent and, in contrast, the heart tissue PCR revealed higher sensitivity regardless of the parasite stock.

Domiciliation of Triatoma pseudomaculata (Corrêa e Espínola 1964) in the Jequitinhonha Valley, State of Minas Gerais

Impact of the vector control program was evaluated eight years after implantation of epidemiological surveillance for ChagasÆ disease in Berilo, a municipality in the Jequitinhonha Valley of the Brazilian State of Minas Gerais. In all 5,242 domiciliary units (96 percent of the total) were inspected and 10 found to be infested by the triatomine bug Triatoma pseudomaculata. Triatomines were found associated with bats inside one house and in the peridomiciles of the other nine. None of the 111 Triatoma pseudomaculata captured was infected with Trypanosoma cruzi. Noireau et al16 traps were installed in (n=8) and around (n=100) the infested house but no Trypanpsoma cruzi-infected triatomines were found. None bat, opossums (Didelphis albiventris) and rat captured in the peridomicile were infected with Trypanosoma cruzi although 24 percent of the inhabitants of the house infested by Triatoma pseudomaculata were seropositive for the parasite, based on ELISA, IHA and IIF.

Oito anos após a implantação da vigilância epidemiológica para doença de Chagas em Berilo, Vale do Jequitinhonha, MG, Brasil, foi realizada uma pesquisa para verificar o impacto do Programa de Controle Vetorial. Neste trabalho, 5. 242 (96 por cento) unidades domiciliares foram vistoriadas. Dez estavam infestadas por Triatoma pseudomaculata. Em nove delas os insetos estavam infestando o peridomicílio e em uma casa foi constatado um foco intradomiciliar associado a morcegos. Foram capturados 111 insetos da espécie Triatoma pseudomaculata e nenhum exemplar estava infectado por Trypanosoma cruzi. Na casa infestada e em torno dela foram instaladas respectivamente 8 e 100 armadilhas de Noireau et al16 e nenhum triatomíneo foi capturado. Oitenta morcegos capturados e examinados também estavam negativos para Trypanosoma cruzi bem como três gambás (Didelphis albiventris) e um roedor, todos capturados no peridomicílio. Um porcentual de 24 por cento dos moradores das casas infestadas por Triatoma pseudomaculata foi sororeativo (ELISA, HAI e IFI) para Tripanosoma cruzi.

Trypanosoma cruzi: treatment with the iron chelator desferrioxamine reduces parasitemia and mortality in experimentally infected mice.

The effects of prolonged treatment with iron chelator (desferrioxamine) on the development of infection in mice inoculated with Y Trypanosoma cruzi were determined. Infected/treated mice presented lower levels of parasitemia and reduced mortality rate compared with infected/non-treated animals. The five out of twenty infected/treated mice that survived the acute phase of infection showed negative hemoculture and positive ELISA in the acute and chronic phases and positive PCR in the acute phase: in the chronic phase, three of the animals presented negative PCR. The single surviving infected/non-treated animal exhibited positive hemoculture, PCR and ELISA in both phases of infection. Infected groups presented lower levels of iron in the liver compared with treated/non-infected or non-treated/non-infected animals. The serum iron levels of the infected/non-treated group were higher on the 21st day post-infection in comparison with control and infected/treated groups. These results suggest that decrease of iron in the host leads to T. cruzi infection attenuation.

Trypanosoma cruzi high infectivity in vitro is related to cardiac lesions during long-term infection in Beagledogs

Trypanosoma cruzi is a hemoflagelate parasite associated with heart dysfunctions causing serious problems in Central and South America. Beagle dogs develop the symptoms of Chagas disease in humans, and could be an important experimental model for better understanding the immunopathogenic mechanisms involved in the chagasic infection. In the present study we investigated the relation among biological factors inherent to the parasite (trypomastigote polymorphism and in vitro infectivity) and immunoglobulin production, inflammation, and fibrosis in the heart of Beagle dogs infected with either T. cruzi Y or Berenice-78 strains. In vitro infectivity of Vero cells as well as the extension of cardiac lesions in infected Beagle was higher for Y strain when compared to Berenice-78 strain. These data suggested that in vitro infectivity assays may correlate with pathogenicity in vivo. In fact, animals infected with Y strain, which shows prevalence of slender forms and high infectivity in vitro, presented cardiomegaly, inflammation, and fibrosis in heart area. Concerning the immunoglobulin production, no statistically significant difference was observed for IgA, IgM or IgG levels among T. cruzi infected animals. However, IgA together IgM levels have shown to be a good marker for the acute phase of Chagas disease.

Reação em cadeia da polimerase (PCR) no diagnóstico da infecção pelo Trypanosoma cruzi em camundongos / Polymerase chain reaction (PCR) for Trypanosoma cruzi infection diagnosis in mice

O objetivo do estudo foi avaliar o desempenho da reação em cadeia da polimerase (PCR) para detectar o DNA de Trypanosoma cruzi no sangue de camundongos infectados com clones do protozoário pertencentes aos genótipos 19, 20 (T. cruzi I), 39 e 32 (T. cruzi II), comparando-o com o exame de sangue a fresco (ESF), a hemocultura (HC) e o teste imunoenzimático (ELISA). Foram analisadasamostras de sangue de camundongos BALB/c experimentalmente infectados com 20 clones. A positividade da PCR foi significativamente superior à das demais técnicas estudadas e a seguinte ordem de positividade foi observada: PCR (100,00) > ELISA(94,44) > HC (78,86) > ESF (73,28). Ao contrário da ELISA, HC e ESF, a positividade da PCR não variou de acordo com o genótipo. Esses dados mostram o potencial da técnica da PCR para o diagnóstico da doença de Chagas.