Many patients with Chagas disease live in remote communities that lack both equipment and trained personnel to perform a diagnosis by conventional serology (CS). Thus, reliable tests suitable for use under difficult conditions are required. In this study, we evaluated the ability of personnel with and without laboratory skills to perform immunochromatographic (IC) tests to detect Chagas disease at a primary health care centre (PHCC). We examined whole blood samples from 241 patients and serum samples from 238 patients. Then, we calculated the percentage of overall agreement (POA) between the two groups of operators for the sensitivity (S), specificity (Sp) and positive (PPV) and negative (NPV) predictive values of IC tests compared to CS tests. We also evaluated the level of agreement between ELISAs and indirect haemagglutination (IHA) tests. The readings of the IC test results showed 100% agreement (POA = 1). The IC test on whole blood showed the following values: S = 87.3%; Sp = 98.8%; PPV = 96.9% and NPV = 95.9%. Additionally, the IC test on serum displayed the following results: S = 95.7%; Sp = 100%; PPV = 100% and NPV = 98.2%. Using whole blood, the agreement with ELISA was 96.3% and the agreement with IHA was 94.1%. Using serum, the agreement with ELISA was 97.8% and the agreement with IHA was 96.6%. The IC test performance with serum samples was excellent and demonstrated its usefulness in a PHCC with minimal equipment. If the IC test S value and NPV with whole blood are improved, then this test could also be used in areas lacking laboratories or specialised personnel.

Background: In Latin America, Chagas disease is endemic, with a high prevalence in rural indigenous communities and an increasing prevalence in urban areas owing to migration from rural areas with active vector transmission. This study aimed to assess differences in the prevalence of Chagas disease in urban and rural moqoit communities, one of the main ethnic indigenous groups in the south of Gran Chaco.Methods: A seroprevalence study was conducted in six moqoit populations in the Santa Fe province, Argentina. The variables studied were serology results for Chagas disease, residents of urban or rural areas, age, and sex. Results:The results showed that 9.26% of the 702 volunteers evaluated and 18.32% of the 131women of childbearing potential were seropositive. According to the calculated prevalence ratio, the prevalence of Chagas disease in urban communities was6.41 (95% confidence inverval: 3.73-11.02) times higher than that in rural communities: 21.59% in urban communities vs. 3.37%in rural communities. Conclusions:The seroprevalence found in the moqoit community was higher than the estimated level for the general population of the same region, with a greater impact in urban areas than in rural areas. The urbanization of groups of people with poor socio-sanitary conditions in the second half of the 20th century could have caused this higher seroprevalence of Chagas disease.

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<strong>Introducción. </strong><span>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. </span><strong>Métodos</strong><span>. 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 </span><em>Trypanosoma cruzi</em><span> 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%. </span><strong>Resultados</strong><span>. 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. </span><strong>Conclusiones</strong><span>. 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.</span>

Background & objectivesIn Latin America, Chagas disease is endemic, with high prevalence in rural indigenous communities and increasing prevalence in urban areas due to migration from rural areas with active vector transmission. The objective of the work was to assess differences in the prevalence of Chagas disease in urban and rural moqoit communities of the south of Gran Chaco, Santa Fe province, Argentina.MethodsA seroprevalence study was conducted in six moqoit populations. Belonging to an urban community was considered as an exposure variable, whereas seropositivity for Chagas disease was considered as an outcome variableResultsThe results showed that 9.26% of the 702 volunteers evaluated and 3.50% of women of childbearing potential were seropositive. The prevalence of Chagas disease in urban communities was 6.41 times higher than in rural communities.Interpretation & conclusionsThe seroprevalence found in the moqoit community is higher than that estimated for the general population of the same region, with greater impact in the urban area than in the rural area. The decline of vector transmission in the rural area could be related to the conservation of ancestral practices and the expansion of the agricultural model.