[Seroprevalence of Chagas´Disease in older than 14 years old in rural Chaco areas of Santa Fe Province.] / Seroprevalencia de Chagas en mayores de 14 años de áreas rurales del Chaco Santafesino.

Introduction: Chagas´Disease (CD) is endemic en Chaco Región. It is unknown the seroprevalence in population older than 14 years old from rural Chaco areas of Santa Fe Province. This study aimed to determine the seroprevalence of and socio-environmental factors associated with CD in inhabitants >14 years old of rural Chaco areas of Santa Fe, Argentina. Methods: A cross-sectional study was conducted between 2010 and 2015, in people over 14 years old, in the rural districts of the Chaco region, in the North of Santa Fe Province, Argentina. Blood serology for Trypanosoma cruzi antibodies based on two serological tests, and a third in case of discordance, were analized. Semi-structured survey was administered. Association between CD and socio-environmental variables were analyzed using prevalence ratios with 95% confidence intervals. Results: A total of 749 individual were analyzed, with an average of 29.5 years. The seroprevalence was 24.70% (26.69% in women and 20.26% in men). Socio-environmental variables showed association with Trypanosoma cruzi seropositive. The seroprevalence was 7.83 times higher in the children of mothers who had not reached secondary education. Conclusions: Chaco region of Santa Fe is endemic for CD, as well as other provinces of the Region. The low level of education is the more important conditioning for this endemic disease.

Introducción: Introducción. La Enfermedad de Chagas (ECh) es endémica en la Región del Chaco. Se desconoce su seroprevalencia en mayores de 14 años de áreas rurales del Chaco Santafesino. El objetivo del trabajo fue determinar la seroprevalencia de ECh en mayores de 14 años de áreas rurales del Chaco Santafesino, Argentina, y su asociación con factores de riesgo epidemiológico. Métodos: Se realizó un estudio transversal entre 2010 y 2015, en personas mayores de 14 años, los distritos rurales de la región del Chaco, en el Norte de la Provincia de Santa Fe, Argentina. Se determinó la prevalencia de anticuerpos contra Trypanosoma cruzi mediante dos pruebas serológicas, realizando una tercera en caso de discordancia. Se realizaron encuestas semiestructuradas sobre variables socioambientales. Se analizó la asociación entre ECh y variables socioambientales mediante la razón de prevalencias con un intervalo de confianza del 95%. Resultados: Se estudió una muestra de 749 personas, con una media de edad de 29,5 años. La seroprevalencia fue de 24,70% (26,69% en mujeres y 20,26% en hombres). Se halló asociación estadísticamente significativa entre las variables socioambientales y la seroprevalencia. La seroprevalencia fue 7,83 veces mayor en los hijos de madres que no habían alcanzado la educación secundaria. Conclusiones: La región del Chaco Santafesino es endémica para Chagas, al igual que otras provincias de la Región. El bajo nivel de instrucción materno es el condicionante más importante para esta endemia

Simple methodology to directly genotype Trypanosoma cruzi discrete typing units in single and mixed infections from human blood samples.

Different DNA markers to genotype Trypanosoma cruzi are now available. However, due to the low quantity of parasites present in biological samples, DNA markers with high copy number like kinetoplast minicircles are needed. The aim of this study was to complete a DNA assay called minicircle lineage specific-PCR (MLS-PCR) previously developed to genotype the T. cruzi DTUs TcV and TcVI, in order to genotype DTUs TcI and TcII and to improve TcVI detection. We screened kinetoplast minicircle hypervariable sequences from cloned PCR products from reference strains belonging to the mentioned DTUs using specific kDNA probes. With the four highly specific sequences selected, we designed primers to be used in the MLS-PCR to directly genotype T. cruzi from biological samples. High specificity and sensitivity were obtained when we evaluated the new approach for TcI, TcII, TcV and TcVI genotyping in twenty two T. cruzi reference strains. Afterward, we compared it with hybridization tests using specific kDNA probes in 32 blood samples from chronic chagasic patients from North Eastern Argentina. With both tests we were able to genotype 94% of the samples and the concordance between them was very good (kappa=0.855). The most frequent T. cruzi DTUs detected were TcV and TcVI, followed by TcII and much lower TcI. A unique T. cruzi DTU was detected in 18 samples meantime more than one in the remaining; being TcV and TcVI the most frequent association. A high percentage of mixed detections were obtained with both assays and its impact was discussed.

Chagas pediátrico en áreas rurales de la provincia de Santa Fe / Pediatric chagas disease in rural areas of Santa Fe province

INTRODUCCIÓN: la enfermedad de Chagas continúa siendo un importante problema de salud pública en la ecoregión del Gran Chaco. El norte de la provincia de Santa Fe, correspondiente al Sur de dicha región, se encuentra bajo control entomológico. Dado que se trata de una infección crónica, la seroprevalencia de esta endemia enniños es un marcador de la situación actual de la infección. OBJETIVOS:Determinar la seroprevalencia de infección chagásica en poblaciónpediátrica del Chaco santafesino. MÉTODOS: Se realizó un estudiodescriptivo de corte transversal sobre seroprevalencia de infección chagásica en niños de 5 a 14 años de edad. Comprendió un área aproximada de 38 000 km2 de distritos rurales de los departamentos 9 de Julio y Vera en la provincia de Santa Fe, y se llevó a cabo entre noviembre de 2010 y abril de 2013. RESULTADOS: Se muestreó al71,5% de los niños de la región (3765/5266). La prevalencia fue de1,8% (67/3765). Varió de 5,5% a 0% entre los distintos distritos. De5 a 9 años, fue 1,2% (21/1769); de 10 a 14 años, 2,3% (46/1996).CONCLUSIONES: La seroprevalencia hallada fue inferior a la de otrosestudios en el Gran Chaco. Se observa una gran heterogeneidad en laprevalencia entre los distritos, aun entre los vecinos. La distribución noobedecería a factores climáticos, sino a factores sociales y a la influenciade la actividad antrópica en cada localidad.

INTRODUCTION: chagas disease remains a major public health problem in the Gran Chaco region. The north of Santa Fe province, being the south of this region, is under entomologicalsurveillance. Being a chronic infection, the seroprevalence of this endemic disease in children serves as a marker of the current status. OBJECTIVES: To determine the seroprevalence of Chagasdisease in the pediatric population of Chaco region in Santa Fe. METHODS: A descriptive, cross-sectional seroprevalence study on Chagas infection was conducted for children aged 5-14 years old. It considered an area of 38 000 km2 belonging to ruraldistricts of 9 de Julio and Vera departments in Santa Fe province,between November 2010 and April 2013. RESULTS: The sampling included 71.5% of the children in the region (3765/5266). There was a prevalence of 1.8% (67/3765), ranged from 5.5% to 0% among districts. For 5-9 years, it was 1.2% (21/1769); for 10-14 years, 2.3% (46/1996). CONCLUSIONS: The seroprevalence was lower than in other studies performed in the Gran Chaco. A large heterogeneity is observed in the prevalence among districts, even among neighboring districts. The distribution does not seem to be due to climatic factors, but to social factors and the influence of human activity in each location.

Genotyping of Trypanosoma cruzi sublineage in human samples from a North-East Argentina area by hybridization with DNA probes and specific polymerase chain reaction (PCR).

We have evaluated blood samples of chronic and congenital Trypanosoma cruzi-infected patients from the city of Reconquista located in the northeast of Argentina where no information was previously obtained about the genotype of infecting parasites. Fourteen samples of congenital and 19 chronical patients were analyzed by hybridization with DNA probes of minicircle hypervariable regions (mHVR). In congenital patients, 50% had single infections with TcIId, 7% single infections with TcIIe, 29% mixed infections with TcIId/e, and 7% had mixed infections with TcIId/b and 7% TcIId/b, respectively. In Chronical patients, 52% had single infections with TcIId, 11% single infections with TcIIe, 26% had mixed infections with TcIId/e, and 11% had non-identified genotypes. With these samples, we evaluated the minicircle lineage-specific polymerase chain reaction assay (MLS-PCR), which involves a nested PCR to HVR minicircle sequences and we found a correlation with hybridization probes of 96.4% for TcIId and 54.8% for TcIIe.

The value of molecular studies for the diagnosis of congenital Chagas disease in northeastern Argentina.

Polymerase chain reaction (PCR) as a diagnostic tool for congenital Chagas disease is scarcely used. To assess the usefulness of PCR, a study in neonates was carried out to compare PCR with standard methods; that is bloodstream parasites by microhematocrit, and/or seroconversion by two conventional procedures. Seventeen neonates, born to mothers with positive Trypanosoma cruzi serology were analyzed by serologic, parasitological and molecular procedures, in blood samples taken at birth, and when aged 2-4 and 9 months. For a better comparison of sensitivity between both parasitological methods (microhematocrit and PCR), the number of samples of neonates studied at birth extended to 121. In children followed-up until 9 months of age, a 100% correlation between PCR and routine diagnosis was found, with PCR showing its highest sensitivity from Month 2 onwards. Comparative analysis between both parasitological methods, on samples taken at birth, showed a higher sensitivity of PCR respect the microhematocrit (P < 0.0008).