[Synthesis of evidence: Guidance for the diagnosis and treatment of Chagas diseaseSíntese de evidências: Guia de diagnóstico e tratamento da doença de Chagas]

Integrating high-throughput analysis to create an atlas of replication origins in Trypanosoma cruzi in the context of genome structure and variability

Trypanosoma cruzi is the etiologic agent of the most prevalent human parasitic disease in Latin America, Chagas disease. Its genome is rich in multigenic families that code for virulent antigens and are present in the rapidly evolving genomic compartment named Disruptive. DNA replication is a meticulous biological process in which flaws can generate mutations and changes in chromosomal and gene copy numbers. Here, integrating high-throughput and single-molecule analyses, we were able to identify Predominant, Flexible, and Dormant Orc1Cdc6-dependent origins as well as Orc1Cdc6-independent origins. Orc1Cdc6-dependent origins were found in multigenic family loci, while independent origins were found in the Core compartment that contains conserved and hypothetical protein-coding genes, in addition to multigenic families. In addition, we found that Orc1Cdc6 density is related to the firing of origins and that Orc1Cdc6-binding sites within fired origins are depleted of a specific class of nucleosomes that we previously categorized as dynamic. Together, these data suggest that Orc1Cdc6-dependent origins may contribute to the rapid evolution of the Disruptive compartment and, therefore, to the success of T. cruzi infection and that the local epigenome landscape is also involved in this process.IMPORTANCETrypanosoma cruzi, responsible for Chagas disease, affects millions globally, particularly in Latin America. Lack of vaccine or treatment underscores the need for research. Parasite's genome, with virulent antigen-coding multigenic families, resides in the rapidly evolving Disruptive compartment. Study sheds light on the parasite's dynamic DNA replication, discussing the evolution of the Disruptive compartment. Therefore, the findings represent a significant stride in comprehending T. cruzi's biology and the molecular bases that contribute to the success of infection caused by this parasite.

[Environmental factors and cardiopulmonary syndrome due to hanta virus in Chile]

OBJECTIVE

Evaluate the relationship between ambient temperature, relative humidity and particulate matter 2,5 with the number of cases Hantavirus Cardiopulmonary Syndrome in Chile between 2015 and 2017.

METHODS

Observational, cross-sectional study in 197 cases of Hantavirus Cardiopulmonary Syndrome reported and confirmed, occurring between 2015 and 2017 in Chile.

RESULTS

Positive and significant relationship was identified between ambient temperature and number of cases of Hantavirus Cardiopulmonary Syndrome and a negative and significant relationship between the number of cases Hantavirus Cardiopulmonary Syndrome and the relative humidity. Also, ambient temperature together with particulate matter 2,5 was observed to increase significantly the number of cases of Hantavirus Cardiopulmonary Syndrome.

CONCLUSIONS

Environmental factors are related to the number of cases Hantavirus Pulmonary Syndrome in Chile between the years 2015 to 2017.

Accuracy of Diagnostic Tests for the Detection of Chagas Disease: A Systematic Review and Meta-Analysis

The present systematic review and meta-analysis about the accuracy of diagnostic tests aim to describe the findings of literature over the last thirty years for the diagnosis of Chagas disease (CD). This work aimed to determine the accuracy of diagnostic techniques for CD in the disease's acute and chronic phases. The PubMed database was searched for studies published between 1990 and 2021 on CD diagnostics. Fifty-six published studies that met the criteria were analyzed and included in the meta-analysis, evaluating diagnostic accuracy through sensitivity and specificity. For Enzyme-Linked Immunosorbent Assay (ELISA), Fluorescent Antibody Technique (IFAT), Hemagglutination Test (HmT), Polymerase Chain Reaction (PCR), and Real-Time Polymerase Chain Reaction (qPCR) diagnosis methods, the sensitivity had a median of 99.0%, 78.0%, 75.0%, 76.0%, and 94.0%, respectively; while specificity presented a median of 99.0%, 99.0%, 99.0%, 98.0%, and 98.0%, respectively. This meta-analysis showed that ELISA and qPCR techniques had a higher performance compared to other methods of diagnosing CD in the chronic and acute phases, respectively. It was concluded utilizing the Area Under the Curve restricted to the false positive rates (AUCFPR), that the ELISA diagnostic test presents the highest performance in diagnosing acute and chronic CD, compared to serological and molecular tests. Future studies focusing on new CD diagnostics approaches should be targeted.

Worldwide Control and Management of Chagas Disease in a New Era of Globalization: a Close Look at Congenital Trypanosoma cruzi Infection

Population movements have turned Chagas disease (CD) into a global public health problem. Despite the successful implementation of subregional initiatives to control vectorial and transfusional Trypanosoma cruzi transmission in Latin American settings where the disease is endemic, congenital CD (cCD) remains a significant challenge. In countries where the disease is not endemic, vertical transmission plays a key role in CD expansion and is the main focus of its control. Although several health organizations provide general protocols for cCD control, its management in each geopolitical region depends on local authorities, which has resulted in a multitude of approaches. The aims of this review are to (i) describe the current global situation in CD management, with emphasis on congenital infection, and (ii) summarize the spectrum of available strategies, both official and unofficial, for cCD prevention and control in countries of endemicity and nonendemicity. From an economic point of view, the early detection and treatment of cCD are cost-effective. However, in countries where the disease is not endemic, national health policies for cCD control are nonexistent, and official regional protocols are scarce and restricted to Europe. Countries of endemicity have more protocols in place, but the implementation of diagnostic methods is hampered by economic constraints. Moreover, most protocols in both countries where the disease is endemic and those where it is not endemic have yet to incorporate recently developed technologies. The wide methodological diversity in cCD diagnostic algorithms reflects the lack of a consensus. This review may represent a first step toward the development of a common strategy, which will require the collaboration of health organizations, governments, and experts in the field.

Indeterminate form of Chagas disease: historical, conceptual, clinical, and prognostic aspects

Chagas disease (CD) remains a serious endemic disease in Latin America and a major public health problem. Because of globalization, the disease has spread to non-endemic areas in the northern hemisphere. In the chronic phase of the disease, most patients present with the indeterminate form (IF), characterized by positive serology for Trypanosoma cruzi, absence of clinical findings, and normal findings in electrocardiogram (ECG). IF was not recognized as a clinical entity until decades after the discovery of the disease, and only in the 1940-50s, it was categorized as a form of CD, and its conceptual definition was ratified in the 1980s. Children, adolescents, and young adults with the IF benefit from etiological treatment and tend to have less progression to heart disease in the long term than the untreated ones. IF patients have an essentially benign clinical condition, and their prognosis can be compared to that of healthy individuals with normal ECG findings. Currently, because of aging, patients with the IF have comorbidities that require attention in health services.

New Biomarker in Chagas Disease: Extracellular Vesicles Isolated from Peripheral Blood in Chronic Chagas Disease Patients Modulate the Human Immune Response

Chagas disease, a neglected tropical disease (NTD) caused by the flagellated protozoan Trypanosoma cruzi (T. cruzi), is a major public health problem. It was initially restricted to Latin America, but it is now expanding globally. Host and pathogen interactions are crucial in the establishment of disease, and since 1970, it has been known that eukaryotic cells release extracellular vesicles (EVs), which in turn have an important role in intercellular communication in physiological and pathological conditions. Our study proposed to characterize and compare circulating EVs isolated from the plasma of chronic Chagas disease (CCD) patients and controls. For this, peripheral blood was collected from patients and controls, and mononuclear cells (PBMCs) were isolated and stimulated with parasite EVs, showing that patient cells released fewer EVs than control cells. Then, after plasma separation followed by EV total shedding enrichment, the samples were subjected to ultracentrifugation to isolate the circulating EVs, which then had their size and concentration characterized by nanoparticle tracking analysis (NTA). This showed that patients had a lower concentration of circulating EVs while there were no differences in size, corroborating the in vitro data. Additionally, circulating EVs were incubated with THP-1 cells (macrophages) that, after the interaction, had their supernatant analyzed by ELISA for cytokine detection. In relation to their ability to induce cytokine production, the CCD patient EVs were able to induce a differential production of IFN-γ and IL-17 in relation to controls, with differences being more evident in earlier/less severe stages of the disease. In summary, a decreased concentration of circulating EVs associated with differential activation of the immunological system in patients with CCD is related to parasite persistence and the establishment of chronic disease. It is also a potential biomarker for monitoring disease progression.

Los Objetivos de Desarrollo Sostenible y las capacidades tecnológicas

Para lograr los objetivos de desarrollo y salud sostenibles, es esencial incrementar las capacidades tecnológicas de las poblaciones más desfavorecidas. Entrado el siglo XXI, existen las tecnologías necesarias para ello. El déficit en capacidades tecnológicas se debe a la existencia de un gradiente tecnológico entre la producción de gran y de pequeña escalas, debido a la falta de incentivos para la innovación y la difusión en empresas y comunidades pequeñas. En estos ámbitos el cambio tecnológico, punto medular del desarrollo, es un bien público que la economía de mercado no provee eficientemente. Su provisión requiere la aplicación de políticas públicas de innovación y difusión tecnológicas. La reducción del gradiente tecnológico constituye, pues, parte medular de la Agenda 2030 para el Desarrollo Sostenible, de las Naciones Unidas, y la Agenda de Salud Sostenible para las Américas 2018-2030, de la Organización Panamericana de la Salud. Esto es aplicable, así mismo, al desarrollo de los sistemas de salud, que funcionan también como mecanismos de redistribución para romper las trampas de pobreza. Asimismo, las experiencias en esos sistemas tienen relevancia para aplicar políticas de incremento de capacidades tecnológicas que disminuyan la pobreza, mejoren los determinantes sociales de la salud y, con ello, reduzcan la magnitud de la trampa de desarrollo humano.

Partos en gestantes remitidas de un territorio disperso e indígena a un hospital universitario

Introducción: en el marco del nuevo modelo de atención en salud, piloto en Colombia, el cuarto nivel de referencia para el departamento de Guainía correspondió a un hospital universitario localizado en Bogotá. Objetivo: caracterizar las gestantes procedentes de Guainía con atención del parto en el Hospital de San José entre junio 2016 y junio 2018. Metodología:  serie de casos con análisis descriptivo de variables. Resultados: 29 fueron embarazos de alto riesgo, edad mediana 24.5 años (rango: 15 a 40), 73% procedían de zona urbana, 72% partos por cesárea, 52% pretérmino. 45% multíparas y dos embarazos gemelares. Todos los diagnósticos de remisión y egreso coincidieron, 55% tuvieron preeclampsia, 24% amenaza de parto pretérmino y 7% restricción del crecimiento intrauterino. En los neonatos 45% tuvieron bajo peso o bajo extremo al nacer, 41% requirieron cuidado intensivo y 38% ingresaron a plan canguro.  No hubo casos de mortalidad materna ni perinatal. Discusión: las cero muertes reflejan el beneficio clínico con la remisión extradepartamental. La alta procedencia urbana puede deberse a fallas de registro y/o difícil acceso de las zonas dispersas. Conclusión: la remisión aérea de gestantes con riesgo alto a una institución predefinida de alta complejidad tiene beneficio clínico. Se requiere optimizar en el territorio de origen la atención prenatal y las acciones de salud pública, en especial preeclampsia y bajo peso al nacer.

Trypanosoma cruzi loop-mediated isothermal amplification (Trypanosoma cruzi Loopamp) kit for detection of congenital, acute and Chagas disease reactivation

A Trypanosoma cruzi Loopamp kit was recently developed as a ready-to-use diagnostic method requiring minimal laboratory facilities. We evaluated its diagnostic accuracy for detection of acute Chagas disease (CD) in different epidemiological and clinical scenarios. In this retrospective study, a convenience series of clinical samples (venous blood treated with EDTA or different stabilizer agents, heel-prick blood in filter paper or cerebrospinal fluid samples (CSF)) from 30 infants born to seropositive mothers (13 with congenital CD and 17 noninfected), four recipients of organs from CD donors, six orally-infected cases after consumption of contaminated guava juice and six CD patients coinfected with HIV at risk of CD reactivation (N = 46 patients, 46 blood samples and 1 CSF sample) were tested by T. cruzi Loopamp kit (Tc LAMP) and standardized quantitative real-time PCR (qPCR). T. cruzi Loopamp accuracy was estimated using the case definition in the different groups as a reference. Cohen's kappa coefficient (κ) was applied to measure the agreement between Tc LAMP (index test) and qPCR (reference test). Sensitivity and specificity of T. cruzi Loopamp kit in blood samples from the pooled clinical groups was 93% (95% CI: 77-99) and 100% (95% CI: 80-100) respectively. The agreement between Tc LAMP and qPCR was almost perfect (κ = 0.92, 95% CI: 0.62-1.00). The T. cruzi Loopamp kit was sensitive and specific for detection of T. cruzi infection. It was carried out from DNA extracted from peripheral blood samples (via frozen EDTA blood, guanidine hydrochloride-EDTA blood, DNAgard blood and dried blood spots), as well as in CSF specimens infected with TcI or TcII/V/VI parasite populations. The T. cruzi Loopamp kit appears potentially useful for rapid detection of T. cruzi infection in congenital, acute and CD reactivation due to HIV infection.

Análisis de concordancia de tres pruebas para el diagnóstico de malaria en la población sintomática de los municipios endémicos de Colombia

Introducción.

Dadas las dificultades del diagnóstico microscópico de la malaria o paludismo en las áreas rurales, las pruebas de diagnóstico rápido constituyen una buena alternativa, por lo que es importante conocer su desempeño.

Objetivo.

Evaluar el desempeño de las pruebas de diagnóstico rápido utilizadas en cinco departamentos para al diagnóstico microscópico de la malaria usando la reacción en cadena de la polimerasa (PCR) como estándar de referencia.

Materiales y métodos.

Se usaron la prueba de gota gruesa y las pruebas de diagnóstico rápido y, además, se impregnó papel de filtro con sangre para la prueba molecular (PCR), en individuos sintomáticos.

Resultados.

Se incluyeron 314 muestras cuyo porcentaje de positividad para malaria fue de 49 % con la PCR, de 48 % con microscopía y de 46 % con las pruebas de diagnóstico rápido; la parasitemia fluctuó entre 180 y 23.800 parásitos/pl de sangre.

La concordancia de los resultados de los puestos de microscopía comparados con la PCR (Laboratorio Nacional de Referencia) fueron los siguientes: coeficiente kappa de Cohen de 0,975 (IC₉₅% 0,950-0,999), sensibilidad de 97 % (IC₉₅% 95-100) y especificidad de 100 % (IC₉₅% 100-100), e índice kappa de especie de 0,958 (IC₉₅% 0,912-1,00).

La concordancia de los resultados de la prueba de diagnóstico rápido Pf/Pv en los puestos de microscopía y los de la PCR (Laboratorio Nacional de Referencia), fue la siguiente: coeficiente kappa de 0,878 (IC₉₅% 0,784-0,973), sensibilidad de 94 % (IC₉₅% 87-100), especificidad de 95 % (IC₉₅% 90-100), e índice kappa de especie de 1,0 (IC₉₅% 1,00-1,00).

La concordancia entre la prueba de diagnóstico rápido Pf/Pan y la PCR fue la siguiente: coeficiente kappa de Cohen de 0,920 (IC₉₅% 0,865-0,974), sensibilidad de 94 % (IC₉₅% 90-98), especificidad de 99 % (IC₉₅% 95-100), e índice kappa de especie de 0,750 (IC₉₅% 0,637-0,863).

Conclusión.

Los resultados de este estudio respaldan el uso de las pruebas de diagnóstico rápido en Colombia, aunque se requiere un mejor entrenamiento del personal para diferenciar eficientemente las especies de Plasmodium.