Infection susceptibility and vector competence of Rhodnius robustus Larrousse, 1927 and R. pictipes Stal, 1872 (Hemiptera, Reduviidae, Triatominae) for strains of Trypanosoma cruzi (Chagas, 1909) (Kinetoplastida, Trypanosomatidae) I, II and IV.

BACKGROUND: Rhodnius robustus and Rhodnius pictipes are vectors of Trypanosoma cruzi, the etiologic agent of Chagas disease (CD), that are found in the Brazilian Amazon region. Susceptibility to infection and vector competence depend on the parasite-vector relationship. Our objective was to evaluate the interaction between T. cruzi and these two triatomine vectors in pure and mixed experimental infections of T. cruzi strains from the same or different geographic regions. METHODS: Fifth-instar nymphs of R. robustus and R. pictipes were fed on mice infected with four T. cruzi strains, namely genotypes TcIAM, TcIMG, TcIIPR, and TcIVAM, respectively, from the Brazilian states of Amazonas, Minas Gerais and Paraná. Over a period of 120 days, excreta were examined every 20 days to assess vector competence, and intestinal contents (IC) were examined every 30 days to determine susceptibility to infection. RESULTS: The highest positive rate in the fresh examination (%+FE, 30.0%), the highest number of parasitic forms (PF, n = 1969) and the highest metacyclogenesis rate (%MC, 53.8%) in the excreta were recorded for R. robustus/TcIVAM. Examination of the IC of R. pictipes revealed a higher number of PF in infections with TcIAM (22,680 PF) and TcIIPR (19,845 PF) alone or in association (17,145 PF), as well as a %+FE of 75.0% with TcII, in comparison with the other genotypes. The highest %MC (100%) was recorded for the mixed infections of TcIAM with TcIIPR or TcIVAM in the IC of R. pictipes. CONCLUSIONS: Overall, both species were found to be susceptible to the T. cruzi strains studied. Rhodnius robustus showed vector competence for genotypes TcIVAM and TcIAM+TcIVAM and R. pictipes for TcIAM+TcIVAM and TcIAM+TcIIPR; there was elimination of infective forms as early as at 20 days. Our results suggest that both the genetics of the parasite and its geographic origin influence the susceptibility to infection and vector competence, alone or in association.

Experimental infection of Rhodnius robustus Larrousse, 1927 (Hemiptera, Reduviidae, Triatominae) with Trypanosoma cruzi (Chagas, 1909) (Kinetoplastida, Trypanosomatidae) IV.

Vector competence of triatomines (kissing bugs) for Trypanosoma cruzi transmission depends on the parasite-vector interaction and the genetic constitution of both. This study evaluates the susceptibility and vector competence of Rhodnius robustus experimentally infected with T. cruzi IV (TcIV). Nymphs were fed on infected mice or an artificial feeder with blood containing culture-derived metacyclic trypomastigotes (CMT) or blood trypomastigotes (BT). The intestinal contents (IC) and excreta of the insects were examined by fresh examination and kDNA-PCR. The rate of metacyclogenesis was also determined by differential counts. Fifth instar nymphs fed with CMT ingested a greater blood volume (mean of 74.5 µL) and a greater amount of parasites (mean of 149,000 CMT/µL), and had higher positivity in the fresh examination of the IC. Third instar nymphs fed with CMT had higher positivity (33.3%) in the fresh examination of the excreta. On the 20th day after infection (dai), infective metacyclic trypomastigote (MT) forms were predominant in the excreta of 3/4 experimental groups, and on the 30th dai, the different parasitic forms were observed in the IC of all the groups. Higher percentages of MT were observed in the excreta of the 5th instar nymphs group (84.1%) and in the IC of the 3rd instar nymphs group (80.0%). Rhodnius robustus presented high susceptibility to infection since all nymphs were infected, regardless of the method used for blood meal, in addition these insects demonstrated vector competence for TcIV with high rates of metacyclogenesis being evident.

A new Trypanosoma cruzi genotyping method enables high resolution evolutionary analyses.

BACKGROUND: Trypanosoma cruzi is an important human pathogen in Latin America with nearly seven million people infected. It has a large degree of genetic diversity, classified into six discrete typing units (DTUs), which probably influences its physiological behavior and clinical manifestations. Several genotyping methods are available, with distinct performance on easiness, cost, resolution and applicability; no method excels in all parameters. OBJECTIVES AND METHODS: To devise a molecular method for T. cruzi genotyping, based on polymerase chain reaction (PCR) amplification of a single target with multiple copies in the nuclear genome by large scale sequencing. We have applied this method to 29 T. cruzi isolates, comprising all described DTUs. FINDINGS: We were able to classify all samples into sub DTU level with high robustness. Evolutionary relationship between DTUs were ascertained, suggesting that TcIII and TcIV DTUs are non-hybrid, and DTU IV is more similar to the common ancestral. CONCLUSION: As the TS-LSS method is based on a single PCR reaction, comprising several copies of the target, it is probably useful for clinical samples, when the amount of DNA is a limiting factor. As large scale sequencing systems become more common, the TS-LSS method can be increasingly applied for T. cruzi genotyping.

Therapeutic effects of benznidazole in Swiss mice that are orally inoculated with Trypanosoma cruzi IV strains from the Western Brazilian Amazon.

Strains of Trypanosoma cruzi, etiological agent of Chagas disease, are classified into different discrete typing units that may present distinct dynamics of infection and susceptibility to benznidazole (BZ) treatment. Mice that were orally inoculated with T. cruzi IV strains exhibited a more intense course of infection compared with intraperitoneally inoculated mice, reflected by higher parasite loads. We evaluated the efficacy of BZ treatment in Swiss mice that were inoculated with T. cruzi IV strains from the Western Brazilian Amazon. The mice were orally (OR) or intraperitoneally (IP) inoculated with 2 × 106 culture-derived metacyclic trypomastigotes of the AM14, AM16, AM64, and AM69 strains of T. cruzi that were obtained from two outbreaks of orally acquired acute Chagas disease in the state of Amazonas, Brazil. The animals were treated with BZ (100 mg/kg/day for 20 days). Fresh blood examination, hemoculture, conventional and quantitative real-time polymerase chain reaction were performed to monitor the therapeutic effects of BZ. Significant reductions in five of 24 parameters of parasitemia and parasite load were found in different tissues in the OR group, indicating worse response to BZ treatment compared with the IP group, in which significant reductions in nine of those 24 parameters were observed. The cure rates in the OR groups ranged from 18.2% (1/11) to 75.0% (9/12) and in the IP groups from 58.3% (7/12) to 91.7% (11/12), for the AM14 and AM69 strains, respectively. These findings indicate that treatment with BZ had fewer beneficial effects with regard to reducing parasitemia and parasite load in different tissues of mice that were OR inoculated with four TcIV strains compared with IP inoculation. Therefore, the route of infection with T. cruzi should be considered when evaluating the therapeutic efficacy of BZ in patients with Chagas disease.

Awareness and understanding of risk factors for intestinal parasitic infections at a public university in southern Brazil / Conocimiento y comprensión de los factores de riesgo de las infecciones parasitarias intestinales en una universidad pública del sur de Brasil / Conscientização e compreensão dos fatores de risco para parasitoses intestinais em uma universidade pública do sul do Brasil

Intestinal parasitoses are highly prevalent in underdeveloped countries such as Brazil. These infirmities may be analyzed looking at the epidemiological triad of the diseases, which consists of host health, the parasite itself and the environment in question. This study aimed to identify the presence of predisposing factors for contamination by enteroparasites in the students of a public university in the South of Brazil. A transversal and descriptive study was carried out with qualitative and quantitative components, and data prospection by means of a questionnaire answered by the students. Only 63.9% of the subjects wash their hands before meals. However, the most alarming factor observed was the environmental instance as the university restrooms are often unclean, which was reported in 99.0% of the questionnaires.

Las parasitosis intestinales son muy frecuentes en países subdesarrollados como Brasil. Estas enfermedades pueden analizarse observando la tríada epidemiológica de las enfermedades, que consiste en la salud del huésped, el parásito en sí y el medio ambiente en cuestión. Este estudio tuvo como objetivo identificar la presencia de factores predisponentes a la contaminación por enteroparásitos en los estudiantes de una universidad pública del Sur de Brasil. Se realizó un estudio transversal y descriptivo con componentes cualitativos y cuantitativos, y prospección de datos mediante un cuestionario respondido por los estudiantes. Solo el 63,9% de los sujetos se lava las manos antes de las comidas. Sin embargo, el factor más alarmante observado fue la instancia ambiental como los baños universitarios son a menudo inmundos, lo que se informó en el 99,0% de los cuestionarios.

As parasitoses intestinais são altamente prevalentes em países subdesenvolvidos como o Brasil. Essas enfermidades podem ser analisadas a partir da tríade epidemiológica das doenças, que consiste na saúde do hospedeiro, o próprio parasita e o meio ambiente em questão. Este estudo teve como objetivo identificar a presença de fatores predisponentes para contaminação por enteroparasitas em estudantes de uma universidade pública do Sul do Brasil. Realizou-se um estudo transversal e descritivo com componentes qualitativa e quantitativa e prospecção de dados por meio de questionário respondido pelos alunos. Apenas 63,9% dos sujeitos lavam as mãos antes das refeições. Porém, o fator mais alarmante observado foi a instância ambiental como os banheiros da universidade são frequentemente impuros, o que foi relatado em 99,0% dos questionários.

Detection of Hemotropic Mycoplasma sp. in white-eared opossums (Didelphis albiventris) from Southern Brazil / Detecção de Mycoplasma sp. hemotrópico em gambás-de-orelha-branca (Didelphis albiventris) no Sul do Brasil

Abstract Opossums are marsupials from the New World of the genus Didelphis and known as synanthropic animals due to their proximity with human beings. To date, 'Candidatus Mycoplasma haemodidelphis' has been solely found infecting the North American opossum (Didelphis virginiana). Accordingly, the aim of this study was to screen eight white-eared opossums (Didelphis albiventris) from a public park in Maringa city, Paraná State, southern Brazil, for hemoplasma infection. Blood samples were taken from caudal venipuncture, and DNA was extracted and further screened by a pan-hemoplasma PCR assay. Seven out of eight (87.50%; CI 95%: 47.35-99.68%) white-eared opossums were positive for Mycoplasma spp. Sequencing of the 16S rRNA fragment showed 98,97% identity with 'Ca. M. haemodidelphis' detected in the USA. Three out of eight (37.50%; CI 95%: 8.52-75.51%) white-eared opossums were infested by Amblyomma dubitatum ticks. This is the first report on detection of a potentially novel hemotropic Mycoplasma sp. infecting opossums from South America.

Resumo Gambás são marsupiais do Novo Mundo, pertencentes ao gênero Didelphis, e considerados animais sinantrópicos devido à sua proximidade com seres humanos. Atualmente, a espécie 'Candidatus Mycoplasma haemodidelphis' só foi encontrada infectando gambá norte americano (Didelphis virginiana). O objetivo do presente estudo foi detectar a infecção por hemoplasmas em oito gambás-de-orelha-branca (Didelphis albiventris) capturados em um parque público da cidade de Maringá, no Estado do Paraná, sul do Brasil. Amostras de sangue foram coletadas por venopunção caudal para a extração do DNA e posterior análise pela PCR para espécies de hemoplasmas. Sete de oito animais (87,50%; CI 95%: 47,35-99,68%) foram considerados positivos para Mycoplasma spp. O sequenciamento do fragmento do gene 16S rRNA obtido apresentou 98.97% de similaridade com sequências de 'Ca. M. haemodidelphis' detectadas nos Estados Unidos. Três gambás (37,50%; CI 95%: 8,52-75,51%) estavam infestados por carrapatos da espécie Amblyomma dubitatum. Esse é o primeiro relato de detecção de uma potencial nova espécie de Mycoplasma hemotrópico infectando gambás na América do Sul.

Detection of Hemotropic Mycoplasma sp. in white-eared opossums (Didelphis albiventris) from Southern Brazil.

Opossums are marsupials from the New World of the genus Didelphis and known as synanthropic animals due to their proximity with human beings. To date, 'Candidatus Mycoplasma haemodidelphis' has been solely found infecting the North American opossum (Didelphis virginiana). Accordingly, the aim of this study was to screen eight white-eared opossums (Didelphis albiventris) from a public park in Maringa city, Paraná State, southern Brazil, for hemoplasma infection. Blood samples were taken from caudal venipuncture, and DNA was extracted and further screened by a pan-hemoplasma PCR assay. Seven out of eight (87.50%; CI 95%: 47.35-99.68%) white-eared opossums were positive for Mycoplasma spp. Sequencing of the 16S rRNA fragment showed 98,97% identity with 'Ca. M. haemodidelphis' detected in the USA. Three out of eight (37.50%; CI 95%: 8.52-75.51%) white-eared opossums were infested by Amblyomma dubitatum ticks. This is the first report on detection of a potentially novel hemotropic Mycoplasma sp. infecting opossums from South America.

Trypanosoma Found in Synanthropic Mammals from Urban Forests of Paraná, Southern Brazil.

Trypanosoma cruzi is a parasitic protozoan that infects a diversity of hosts constituting the cycle of enzootic transmission in wild environments and causing disease in humans (Chagas disease) and domestic animals. Wild mammals constitute natural reservoirs of this parasite, which is transmitted by hematophagous kissing bugs of the family Reduviidae. T. cruzi is genetically subdivided into six discrete typing units (DTUs), T. cruzi (Tc)I to TcVI. In Brazil, especially in the state of Paraná, TcI and TcII are widely distributed. However, TcII is less frequently found in wild reservoirs and triatomine, and more frequently found in patients. The goal of this study was to investigate the natural occurrence of T. cruzi in wild synanthropic mammals captured in urban forest fragments of the Atlantic Forest of Paraná, southern Brazil. In this way, 12 opossums and 35 bats belonging to five species were captured in urban forest parks of the city of Maringá, Paraná, an area considered endemic for Chagas disease. PCR-kinetoplast DNA molecular diagnostic reveals Trypanosoma sp. infection in 12 (100%) Didelphis albiventris and 10 (40%) Artibeus lituratus. In addition to demonstrating the presence of Trypanosoma in the two groups of mammals studied, we obtained an isolate of the parasite genotyped as TcII by amplification of the cytochrome oxidase II gene by PCR, followed by restriction fragment length polymorphism with AluI, and confirmed by PCR of rDNA 24Sα. This is the first record of the encounter in wild mammals of Trypanosoma DNA (in A. lituratus) and T. cruzi DTU TcII (in D. albiventris) in the state of Paraná.

Spatial prediction of risk areas for vector transmission of Trypanosoma cruzi in the State of Paraná, southern Brazil.

After obtaining certification of the absence of transmission of the Trypanosoma cruzi by Triatoma infestans in 2006, other native species of protozoan vectors have been found in human dwellings within municipalities of the State of Paraná, Southern Brazil. However, the spatial distribution of T. cruzi vectors and how climatic and landscape combined variables explain the distribution are still poorly understood. The goal of this study was to predict the potential distribution of T. cruzi vectors as a proxy for Chagas disease transmission risk using Ecological Niche Models (ENMs) based on climatic and landscape variables. We hypothesize that ENM based on both climate and landscape variables are more powerful than climate-only or landscape-only models, and that this will be true independent of vector species. A total of 2,662 records of triatomines of five species were obtained by community-based entomological surveillance from 2007 to 2013. The species with the highest number of specimens was Panstrongylus megistus (73%; n = 1,943), followed by Panstrongylus geniculatus (15.4%; 411), Rhodnius neglectus (6.0%; 159), Triatoma sordida (4.5%; 119) and Rhodnius prolixus (1.1%; 30). Of the total, 71.9% were captured at the intradomicile. T. cruzi infection was observed in 19.7% of the 2,472 examined insects. ENMs were generated based on selected climate and landscape variables with 1 km2 spatial resolution. Zonal statistics were used for classifying the municipalities as to the risk of occurrence of synanthropic triatomines. The integrated analysis of the climate and landscape suitability on triatomines geographical distribution was powerful on generating good predictive models. Moreover, this showed that some municipalities in the northwest, north and northeast of the Paraná state have a higher risk of T. cruzi vector transmission. This occurs because those regions present high climatic and landscape suitability values for occurrence of their vectors. The frequent invasion of houses by infected triatomines clearly indicates a greater risk of transmission of T. cruzi to the inhabitants. More public health attention should be given in the northern areas of the State of Paraná, which presents high climate and landscape suitabilities for the disease vectors. In conclusion, our results-through spatial analysis and predictive maps-showed to be effective in identifying areas of potential distribution and, consequently, in the definition of strategic areas and actions to prevent new cases of Chagas' disease, reinforcing the need for continuous and robust surveillance in these areas.

Epidemiological and clinical profile of patients with Chagas disease in the Central-North area of Paraná, Southern Brazil.

INTRODUCTION: Profiles of patients with Chagas disease in Paraná were studied. METHODS: A descriptive, questionnaire-based study was performed. RESULTS: Of 270 participants, 64% were female, 60% were aged ≥65 years, 91% were infected via vector transmission, and 44% were infected in Paraná. Indeterminate (30%), cardiac (36%), cardiodigestive (20%) and digestive (14%) forms were found. CONCLUSIONS: Patients who were older than 65 years of age, retired, female, living in the urban area of Maringá, and infected by vector transmission in childhood in Paraná presented cardiac and digestive signs and did not receive etiological treatment when first diagnosed.

Epidemiological and clinical profile of patients with Chagas disease in the Central-North area of Paraná, Southern Brazil

Abstract INTRODUCTION Profiles of patients with Chagas disease in Paraná were studied. METHODS A descriptive, questionnaire-based study was performed. RESULTS Of 270 participants, 64% were female, 60% were aged ≥65 years, 91% were infected via vector transmission, and 44% were infected in Paraná. Indeterminate (30%), cardiac (36%), cardiodigestive (20%) and digestive (14%) forms were found. CONCLUSIONS: Patients who were older than 65 years of age, retired, female, living in the urban area of Maringá, and infected by vector transmission in childhood in Paraná presented cardiac and digestive signs and did not receive etiological treatment when first diagnosed.

Efficacy of essential oil of Syzygium aromaticum alone and in combination with benznidazole on murine oral infection with Trypanosoma cruzi IV.

Chagas disease (CD), caused by Trypanosoma cruzi, remains a serious public health problem. One of the causes of the high morbidity and mortality in patients is the lack of an effective drug therapy. Thus, the aim of this study was to evaluate the efficacy of the essential oil of Syzygium aromaticum alone and in combination with benznidazole (BZ) in mice orally inoculated with strain of T. cruzi IV obtained from oral CD outbreak occurred in Western Brazilian Amazonia. All the animals inoculated with metacyclic trypomastigote forms (AM14 strain, BZ resistant), derived from the insect Rhodnius robustus, became infected and there was no difference in the mortality rate between the experimental groups. When compared with untreated control animals (UTC), the treatment with essential oil of S. aromaticum (EOSA) alone promoted reduction in 1/5 parameters derived from the parasitemia curve, whereas the treatments with BZ alone or in combination (BZ + EOSA) promoted reduction in 4/5 of those parameters, presenting similar profiles of parasitemia curve. The animals treated with BZ and with the combination BZ + EOSA presented lower patency periods in comparison with the animals in EOSA group, and lower positivity of blood cultures when compared with the UTC group. The results of molecular analysis by qPCR in both blood and cardiac tissue did not show differences between the groups. The cure rates obtained with the different treatments presented the following ascending order: EOSA = 12.5% (1/8), BZ = 25.0% (2/8) and BZ + EOSA = 37.5% (3/8). Although there are no significant differences between them, these results claims that the use of this essential oil could be of interest for treatment of Chagas disease.

Sympatry influence in the interaction of Trypanosoma cruzi with triatomine.

INTRODUCTION: Trypanosoma cruzi, the etiologic agent of Chagas disease, is widely distributed in nature, circulating between triatomine bugs and sylvatic mammals, and has large genetic diversity. Both the vector species and the genetic lineages of T. cruzi present a varied geographical distribution. This study aimed to verify the influence of sympatry in the interaction of T. cruzi with triatomines. Methods: The behavior of the strains PR2256 (T. cruzi II) and AM14 (T. cruzi IV) was studied in Triatoma sordida (TS) and Rhodnius robustus (RR). Eleven fifth-stage nymphs were fed by artificial xenodiagnosis with 5.6 × 103 blood trypomastigotes/0.1mL of each T. cruzi strain. Every 20 days, their excreta were examined for up to 100 days, and every 30 days, the intestinal content was examined for up to 120 days, by parasitological (fresh examination and differential count with Giemsa-stained smears) and molecular (PCR) methods. Rates of infectivity, metacyclogenesis and mortality, and mean number of parasites per insect and of excreted parasites were determined. RESULTS: Sympatric groups RR+AM14 and TS+PR2256 showed higher values of the four parameters, except for mortality rate, which was higher (27.3%) in the TS+AM14 group. General infectivity was 72.7%, which was mainly proven by PCR, showing the following decreasing order: RR+AM14 (100%), TS+PR2256 (81.8%), RR+PR2256 (72.7%) and TS+AM14 (36.4%). CONCLUSIONS: Our working hypothesis was confirmed once higher infectivity and vector capacity (flagellate production and elimination of infective metacyclic forms) were recorded in the groups that contained sympatric T. cruzi lineages and triatomine species.

Sympatry influence in the interaction of Trypanosoma cruzi with triatomine

Abstract INTRODUCTION: Trypanosoma cruzi, the etiologic agent of Chagas disease, is widely distributed in nature, circulating between triatomine bugs and sylvatic mammals, and has large genetic diversity. Both the vector species and the genetic lineages of T. cruzi present a varied geographical distribution. This study aimed to verify the influence of sympatry in the interaction of T. cruzi with triatomines. Methods: The behavior of the strains PR2256 (T. cruzi II) and AM14 (T. cruzi IV) was studied in Triatoma sordida (TS) and Rhodnius robustus (RR). Eleven fifth-stage nymphs were fed by artificial xenodiagnosis with 5.6 × 103 blood trypomastigotes/0.1mL of each T. cruzi strain. Every 20 days, their excreta were examined for up to 100 days, and every 30 days, the intestinal content was examined for up to 120 days, by parasitological (fresh examination and differential count with Giemsa-stained smears) and molecular (PCR) methods. Rates of infectivity, metacyclogenesis and mortality, and mean number of parasites per insect and of excreted parasites were determined. RESULTS: Sympatric groups RR+AM14 and TS+PR2256 showed higher values of the four parameters, except for mortality rate, which was higher (27.3%) in the TS+AM14 group. General infectivity was 72.7%, which was mainly proven by PCR, showing the following decreasing order: RR+AM14 (100%), TS+PR2256 (81.8%), RR+PR2256 (72.7%) and TS+AM14 (36.4%). CONCLUSIONS: Our working hypothesis was confirmed once higher infectivity and vector capacity (flagellate production and elimination of infective metacyclic forms) were recorded in the groups that contained sympatric T. cruzi lineages and triatomine species.

Polymorphisms of blood forms and in vitro metacyclogenesis of Trypanosoma cruzi I, II, and IV.

Trypanosoma cruzi is the etiologic agent of American trypanosomiasis has broad biological and genetic diversity. Remaining to be studied are polymorphisms of the blood forms and metacyclogenesis of different T. cruzi discrete typing units (DTUs). Our goal was to evaluate the relationship between T. cruzi DTUs, the morphology of blood trypomastigotes, and in vitro metacyclogenesis. T. cruzi strains that pertained to DTUs TcI, TcII, and TcIV from different Brazilian states were used. Parameters that were related to the morphology of eight strains were assessed in thin blood smears that were obtained from mice that were inoculated with blood or culture forms, depending on strain. The metacyclogenesis of 12 strains was measured using smears with Liver Infusion Tryptose culture medium and M16 culture medium (which is poor in nutrients and has a low pH) at the exponential phase of growth, both stained with Giemsa. The morphological pattern of TcII strains was consistent with broad forms of the parasite. In TcIV strains, slender forms predominated. The Y strain (TcII) was morphologically more similar to TcIV. Significant differences in polymorphisms were observed between DTUs. Metacyclogenesis parameters, although displaying large standard deviations, differed between the DTUs, with the following descending rank order: TcII > TcI > TcIV. The mean numbers of metacyclic trypomastigotes for TcII were significantly higher than the other DTUs. Although the DTUs presented overlapping characteristics, the general pattern was that different DTUs exhibited significantly different morphologies and metacyclogenesis, suggesting that the genetic diversity of T. cruzi could be related to parameters that are associated with the evolution of infection in mammalian hosts and its ability to disperse in nature.

TcI, TcII and TcVI Trypanosoma cruzi samples from Chagas disease patients with distinct clinical forms and critical analysis of in vitro and in vivo behavior, response to treatment and infection evolution in murine model.

The clonal evolution of Trypanosoma cruzi sustains scientifically the hypothesis of association between parasite's genetic, biological behavior and possibly the clinical aspects of Chagas disease in patients from whom they were isolated. This study intended to characterize a range of biological properties of TcI, TcII and TcVI T. cruzi samples in order to verify the existence of these associations. Several biological features were evaluated, including in vitro epimastigote-growth, "Vero"cells infectivity and growth, along with in vivo studies of parasitemia, polymorphism of trypomastigotes, cardiac inflammation, fibrosis and response to treatment by nifurtimox during the acute and chronic murine infection. The global results showed that the in vitro essays (acellular and cellular cultures) TcII parasites showed higher values for all parameters (growth and infectivity) than TcVI, followed by TcI. In vivo TcII parasites were more virulent and originated from patients with severe disease. Two TcII isolates from patients with severe pathology were virulent in mice, while the isolate from a patient with the indeterminate form of the disease caused mild infection. The only TcVI sample, which displayed low values in all parameters evaluated, was also originated of an indeterminate case of Chagas disease. Response to nifurtimox was not associated to parasite genetic and biology, as well as to clinical aspects of human disease. Although few number of T. cruzi samples have been analyzed, a discreet correlation between parasite genetics, biological behavior in vitro and in vivo (murine model) and the clinical form of human disease from whom the samples were isolated was verified.

Trypanosoma cruzi: Evaluation of PCR as a Laboratory Tool to Follow up the Evolution of Parasite Load.

BACKGROUND: The study evaluated qualitative PCR, primers 121-122 as a tool to follow up evolution parasite load of Trypanosoma cruzi. METHODS: The study was conducted at the State University of Maringa, in 2015. Step 1, dilutions 1/10 were performed from T. cruzi-Y strain to obtain preparations of 50,000-0.05 parasites/mL from which DNA were extracted, quantified, and amplified. Step 2, the extracted DNA in the dilutions 5-0.05 parasites/mL was re-diluted 1/10, 1/100, 1/1000, quantified, and amplified. Polyacrylamide gels were photographed and thicknesses of the 330 bp kDNA fragments were measured. RESULTS: Step 1, in the dilutions 50,000-50 parasites/mL kDNA fragments had same thickness and, dilutions 5-0.05 parasites/mL showed progressive decrease in thicknesses and staining intensity of the 330 bp fragments. Step 2, demonstrated that dilutions of five (re-dilutions 1/10 and 1/100) and 0.5 (1/10) parasites/mL produced similar thicknesses of the 330 bp fragments obtained in Step 1. However, very dilute DNA samples make difficult to reproduce the fragments thicknesses. CONCLUSION: PCR, despite its limitations, was able to detect progressive decrease in thicknesses/staining intensity of kDNA fragments in the dilutions 5-0.05 parasites/mL. Hence, has the potential to be used to follow-up evolution of parasite load, not by quantifying the number of parasites, but by dynamic evolution of the fragments thicknesses during etiological treatment.

Trypanosoma cruzi: biotherapy made from trypomastigote modulates the inflammatory response.

UNLABELLED: This study evaluates the effect of Trypanosoma cruzi biotherapy 17dH (BIOT) on mice of different ages, infected with the protozoa concerned. METHOD: Performing a blind, controlled, randomized by drawing experiment, 110 animals four or eight-week-old, Swiss, male mice were divided into infected control treated hydroalcoholic 7% (CI-4 = 34 or CI-8 = 21 animals) and infected control treated with biotherapy 17dH-0.2 mL/animal/20 consecutive days/oral regimen (BIOT-4 = 33 or BIOT-8 = 21 animals). Animals were inoculated intraperitoneally with 1400 trypomastigote, T. cruzi Y-strain. Parasitological, immunological and histopathologic parameters were evaluated statistically, using Statistica-8.0 and R 3.0.2 program to analysis of survival. The study was approved by the Ethics Committee for Animal Experimentation/UEM. RESULTS: Four-week-old mice showed no statistical difference in parasitemia (P = 0.5718) between the treated and control group. Eight-week-old mice from the treated group had a higher parasite peak (P = 0.0424) and higher parasitemia (P < 0.005) than the control. To both groups of 4 and 8 weeks of age, treated or untreated, survival of mice was higher in the treated group than in the control, although it was not statistically significant (p-value = 0.32, 0.55 respectively). Four-week-old mice displayed a spleen section with a number of amastigote nests significantly higher in BIOT-4 than CI-4 (P = 0.01). In eight-week-old mice the number of amastigote nests (P < 0.001) and inflammatory foci (P < 0.06-10% significance) in the liver section were smaller in BIOT-8 than CI-8. Spleen giant cells were significantly higher in CI-8 than in BIOT-8 (P < 0.01). Eight-week-old animals treated with biotherapy showed higher parasitemia and lower tissue parasitism. Opposite pattern was observed in four-week-old animals. CONCLUSION: There is a difference of high diluted medication effect in four and eight-week-old mice. In the group of animals 8 weeks the immunomodulatory effect seems to have been higher. Hence, treatment with the medicine produced from T. cruzi modulates the inflammatory response with increased apoptosis and decreased serum levels of TGF-ß.

Comparative pathogenicity in Swiss mice of Trypanosoma cruzi IV from northern Brazil and Trypanosoma cruzi II from southern Brazil.

The geographical heterogeneity of Chagas disease (ChD) is mainly caused by genetic variability of the etiological agent Trypanosoma cruzi. Our hypothesis was that the pathogenicity for mice may vary with the genetic lineage (or Discrete Typing Unit - DTU) of the parasite. To test this hypothesis, parasitological and histopathological evaluations were performed in mice inoculated with strains belonging to the DTU T. cruzi IV (TcIV) from the State of Amazonas (northern Brazil), or the DTU T. cruzi II (TcII) from the State of Paraná (southern Brazil). Groups of 10 Swiss mice were inoculated with eight strains of TcIV obtained from acute cases (7) from two outbreaks of orally acquired ChD, and from the triatomine Rhodnius robustus (1) from Amazonas; and three strains of TcII obtained from chronic patients in Paraná. We evaluated the pre-patent period, patent period, maximum peak of parasitemia, day of maximum peak of parasitemia, area under the parasitemia curve, inflammatory process, and tissue parasitism in the acute phase. TcIV was less virulent than TcII, and showed significantly (p < 0.005) lower parasitemia levels. Although the levels of tissue parasitism did not differ statistically, mice infected with TcIV displayed significantly (p < 0.001) fewer inflammatory processes than mice infected with TcII. This supported the working hypothesis, since TcIV from Amazonas was less pathogenic than TcII from Paraná; and agreed with the lower severity of human cases of ChD in the Amazon region.