Martha Lucía Díaz

Respiratory syncytial virus (RSV) and rhinovirus (RV) are major causes of acute respiratory infections (ARIs) worldwide. The circulation of both RSV and RV was notably altered during the COVID-19 pandemic. This study analyzed the epidemiological and molecular characteristics of RSV and RV in Santander, Colombia, during the pandemic period (PP, 2020–2021) and the post-pandemic period (PPP, 2023–2024). A total of 921 respiratory samples from patients with ARIs were screened for RSV-A/B and RV. Sequences of the RSV attachment glycoprotein (G) gene and the RV VP4–VP2 region were analyzed in positive samples. Epidemiological and clinical characteristics of the study population were also assessed. RSV was not detected during PP, whereas RV was detected in 4.8% of samples. During PPP, RSV-A, RSV-B, and RV were detected in 5.6%, 4.4%, and 28.0% of samples, respectively. RSV infections were mainly identified in children, while RV was detected across all age groups. RSV-A sequences grouped within seven A.D-derived lineages (A.D.1.5, A.D.1.7, A.D.1.8, A.D.3.2, A.D.3.3, A.D.5.1, A.D.5.2), whereas RSV-B sequences clustered within the B.D.E.1 lineage. RV showed a higher number of detected genotypes during the PPP than during the PP. The genotypic characterization performed in this study provides new insight into the molecular epidemiology of RSV and RV in Santander, Colombia, during PP and PPP, and represents, to our knowledge, the first regional description of RSV lineages and RV genotypes across these periods.

Cutaneous Leishmaniasis (CL) is a tropical disease endemic in many regions of Latin America. Its clinical diagnosis is often supported by histopathological analysis of skin biopsies; however, parasite detection by microscopy can be challenging, particularly in chronic or pauciparasitic lesions, leading to inconclusive results. Objective: This study aimed to evaluate the utility of polymerase chain reaction (PCR) as a confirmatory diagnostic tool for CL in formalin-fixed, paraffin-embedded (FFPE) biopsies with inconclusive histopathology. Methods: We analyzed 16 FFPE skin biopsy samples from patients with clinical suspicion of CL. All cases underwent routine histopathological evaluation using hematoxylin and eosin staining and were classified as inconclusive. DNA was extracted and PCR was performed, targeting the ITS1 and miniexon regions of Leishmania spp. Results: PCR successfully amplified Leishmania DNA in 8 (50%) out of 16 samples when both targets were utilized, confirming infection. These findings highlight the additional benefits of molecular tools in cases with inconclusive histopathology, thereby enhancing diagnostic accuracy and enabling species-level identification in certain instances. Conclusions: PCR proved to be a valuable diagnostic complement to histopathology in clinically and histologically suspected cases of CL without visible parasites. Its implementation may improve diagnostic accuracy and timely treatment in endemic areas.

Introducción: Las infecciones respiratorias agudas (IRA) causadas por virus respiratorios constituyen una fuente importante de morbilidad y mortalidad en el mundo. Nos propusimos determinar la prevalencia de virus respiratorios en pacientes con sospecha de infección por SARS-CoV-2 y explorar la asociación entre coinfección de SARS-CoV-2 con otros virus respiratorios con la gravedad de la enfermedad respiratoria aguda. Métodos: Estudio de corte transversal, se analizaron hisopados de pacientes con síntomas sugestivos de COVID-19 en Santander, Colombia. Se seleccionaron muestras positivas y negativas para SARS-CoV-2 mediante un muestreo probabilístico proporcional. La detección de 15 virus se realizó mediante RT-qPCR en hisopados almacenados a -80°C. Se tomaron datos clínicos y epidemiológicos de las fichas epidemiológicas remitidas junto con la muestra respiratoria, para establecer la condición de gravedad (hospitalización o muerte por IRA). Resultados: Se incluyeron 600 hisopados colectados entre abril del 2020 y noviembre del 2021. La mediana de edad de los pacientes fue 55,0 años [RIC: 34,0] y el 58,5% fueron hombres. La prevalencia de rinovirus y adenovirus C fue de 4,7% y 0,3%, respectivamente. La prevalencia de coinfección de SARS-CoV-2 con rinovirus y adenovirus C fue de 3,3% (IC95%: 1,7-5,5) y 0,3% (IC95%: 0,0-1,4), respectivamente. Al momento de la toma de muestras, el 30,2 % correspondía a pacientes ambulatorios, el 59,8 % a pacientes hospitalizados y el 10,0 % a casos fatales. Se observó una diferencia en el reporte de comorbilidades entre los casos y controles (61,0 % vs. 46,5 %; p = 0,012). No se encontró asociación entre coinfección y la gravedad de la enfermedad (OR: 1,01; IC95%: 0,33 - 3,10), ajustando por edad, sexo, seguridad social y comorbilidades. Conclusiones: Durante el periodo epidémico la circulación de otros virus respiratorios fue baja. No observamos una asociación entre coinfección y gravedad de la enfermedad en las muestras evaluadas.

Chronic Chagas cardiomyopathy (CCC) is the most frequent and severe clinical form of chronic Chagas disease, representing one of the leading causes of morbidity and mortality in Latin America, and a growing global public health problem. There is currently no approved treatment for CCC; however, omics technologies have enabled significant progress to be made in the search for new therapeutic targets. The metabolic alterations associated with pathogenic mechanisms of CCC and their relationship to cellular and immunopathogenic processes in cardiac tissue remain largely unknown. This exploratory study aimed to evaluate the potential underlying pathogenic mechanisms in the failing myocardium of patients with end-stage heart failure (ESHF) secondary to CCC by applying an untargeted metabolomic profiling approach. Cardiac tissue samples from the left ventricle of patients with ESHF of CCC etiology (n = 7) and healthy donors (n = 7) were analyzed using liquid chromatography-mass spectrometry. Metabolite profiles showed altered branched-chain amino acid and acylcarnitine levels, decreased fatty acid uptake and oxidation, increased activity of the pentose phosphate pathway, dysregulation of the TCA cycle, and alterations in critical cellular antioxidant systems. These findings suggest processes of energy deficit, alterations in substrate availability, and enhanced production of reactive oxygen species in the affected myocardium. This profile potentially contributes to the development and maintenance of a chronic inflammatory state that leads to progression and severity of CCC. Further studies involving larger sample sizes and comparisons with heart failure patients without CCC are needed to validate these results, opening an avenue to investigate new therapeutic approaches for the treatment and prevention of progression of this unique and severe cardiomyopathy.

Sensitivity and efficiency of RNA sample pooling for real-time quantitative polymerase chain reaction testing for SARS-CoV-2 Leonelo E. Bautista, Luis A. Villar, Mario A. Cleves, Margarita Gelvez, Anyela Lozano-Parra, Nathalia Bueno-Ariza, Myriam Oróstegui, Ruth A. Martínez-Vega, Martha Díaz-Galvis

Chagas disease is an infection caused by the parasite Trypanosoma cruzi, endemic in Latino America. Leveraging the three-way admixture between Native American (AMR), European (EUR) and African (AFR) populations in Latin Americans, we aimed to better understand the genetic basis of Chagas disease by performing an admixture mapping study in a Colombian population. A two-stage study was conducted, and subjects were classified as seropositive and seronegative for T. cruzi. In stage 1, global and local ancestries were estimated using reference data from the 1000 Genomes Project (1KGP), and local ancestry associations were performed by logistic regression models. The AMR ancestry showed a protective association with Chagas disease within the major histocompatibility complex region [Odds ratio (OR) = 0.74, 95% confidence interval (CI) = 0.66–0.83, lowest P-value = 4.53 × 10⁻⁸]. The fine mapping assessment on imputed genotypes combining data from stage 1 and 2 from an independent Colombian cohort, revealed nominally associated variants in high linkage disequilibrium with the top signal (rs2032134, OR = 0.93, 95% CI = 0.90–0.97, P-value = 3.54 × 10⁻⁴) in the previously associated locus. To assess ancestry-specific adaptive signals, a selective sweep scan in an AMR reference population from 1KGP together with an in silico functional analysis highlighted the Tripartite Motif family and the human leukocyte antigen genes, with crucial role in the immune response against pathogens. Furthermore, these analyses emphasized the macrophages, neutrophils and eosinophils, as key players in the defense against T. cruzi. This first admixture mapping study in Chagas disease provided novel insights underlying the host immune response in the pathogenesis of this neglected disease.

Objectives: To analyse the effect of parasite load assessed by quantitative reverse transcription PCR (RT‐qPCR) in serum on the prognosis of patients with chronic Chagas cardiomyopathy (CCM) after a 2‐year follow‐up.Methods: Prospective cohort study conducted between 2015 and 2017. One hundred patients with CCM were included. Basal parasitaemia levels of Trypanosoma cruzi (T. cruzi) were measured using a quantitative polymerase chain reaction (qPCR) test. The primary composite outcome (CO) was all‐cause mortality, cardiac transplantation and implantation of a left ventricular assist device. Secondary outcomes were the baseline levels of serum biomarkers and echocardiographic variables.Results: After a 2 years of follow‐up, the primary CO rate was 16%. A positive qPCR was not associated with a higher risk of the CO. However, when parasitaemia was evaluated by comparing tertiles (tertile 1: undetectable parasitaemia, tertile 2: low parasitaemia and tertile 3: high parasitaemia), a higher risk of the CO (HR 3.66; 95% CI 1.11–12.21) was evidenced in tertile 2. Moreover, patients in tertile 2 had significantly higher levels of high‐sensitivity troponin T and cystatin C and more frequently exhibited an ejection fraction T. cruzi load more efficiently, but be associated with increased myocardial damage. Additional studies with a larger number of patients and cytokine measurement are required to support this hypothesis.

Outbreaks of acute Chagas disease associated with oral transmission are easily detected nowadays with trained health personnel in areas of low endemicity, or in which the vector transmission has been interrupted. Given the biological and genetic diversity of Trypanosoma cruzi, the high morbidity, mortality, and the observed therapeutic failure, new characteristics of these outbreaks need to be addressed at different levels, both in Trypanosoma cruzi as in patient response. The aim of this work was to evaluate the patient’s features involved in six outbreaks of acute Chagas disease which occurred in Santander, Colombia, and the characteristics of Trypanosoma cruzi clones isolated from these patients, to establish the potential relationship between the etiologic agent features with host behavior. The clinical, pathological and epidemiological aspects of outbreaks were analyzed. In addition, Trypanosoma cruzi clones were biologically characterized both in vitro and in vivo, and the susceptibility to the classical trypanocidal drugs nifurtimox and benznidazole was evaluated. Trypanosoma cruzi clones were genotyped by means of mini-exon intergenic spacer and cytochrome b genes sequencing. All clones were DTU I, and based on the mini-exon intergenic spacer, belong to two genotypes: G2 related with sub-urban, and G11 with rural outbreaks. Girón outbreak clones with higher susceptibility to drugs presented G2 genotype and C/T transition in Cyt b. The outbreaks affected mainly young population (±25.9 years), and the mortality rate was 10 %. The cardiac tissue showed intense inflammatory infiltrate, myocardial necrosis and abundant amastigote nests. However, although the gastrointestinal tissue was congestive, no inflammation or parasites were observed. Although all clones belong to DTU I, two intra-DTU genotypes were found with the sequencing of the mini-exon intergenic spacer, however there is no strict correlation between genetic groups, the cycles of the parasite or the clinical forms of the disease. Trypanosoma cruzi clones from Girón with higher sensitivity to nifurtimox presented a particular G2 genotype and C/T transition in Cyt b. When the diagnosis was early, the patients responded well to antichagasic treatment, which highlights the importance of diagnosis and treatment early to prevent fatal outcomes associated with these acute episodes.