Andrew Keith Falconar

Se identificó el genotipo TcI de Trypanosoma cruzi en poblaciones silvestres y con tendencia a la domiciliación de Panstrongylus geniculatus en el departamento del Atlántico, Colombia. Mediante búsqueda activa y trampas de luz en zonas rurales y urbanas de tres municipios se capturaron 33 ejemplares de P. geniculatus: Usiacurí (2), Piojó (2) y Tubará (29), estos últimos recolectados en cinco viviendas. El ADN del contenido digestivo fue analizado por PCR empleando marcadores moleculares (DNAk, Mini-Exón, 18S, DNAr). Se evidenció infección por T. cruzi en el 75% de los especímenes (25/33), todos procedentes de Tubará, con identificación exclusiva del genotipo TcI. Adicionalmente, se calcularon índices entomológicos, con índices de infestación, colonización e infección natural del 60%, 33% y 86%, respectivamente. Estos hallazgos constituyen el primer reporte de T. cruzi TcI en el departamento del Atlántico y el primer registro de P. geniculatus en Usiacurí, lo que evidencia un riesgo potencial para la salud pública colombiana.

Chikungunya virus (CHIKV), a mosquito-borne alphavirus, causes acute febrile illness that can progress into chronic arthritis-like disease (CHIKVD) in humans. CD4⁺ T cells have important functions in CHIKV infection, yet the CHIKV target proteins for these CD4 + T cells are poorly characterized. Here, by stimulating PBMCs collected from individuals with chronic CHIKVD with peptides spanning the entire CHIKV proteome, we provide a comprehensive landscape of CHIKV CD4⁺ T cell epitopes. We identify three immunodominant regions and associated core motifs in CHIKV E1, nsP1 and CP proteins. In addition, by in silico assessment of the sequence conservation of CHIKV proteome with closely related alphaviruses, we define CHIKV epitopes conserved across arthritogenic and encephalitic viruses. Overall, our work describes CD4⁺ T cell targets of CHIKV in humans, thereby assisting in studying the functions of CD4⁺ T cells in CHIKV pathogenesis and vaccine design.

To assess whether the ‘economic boom’ in the tropical seaport city of Barranquilla improved tapped water supplies to socio-economically poor neighbourhoods resulting in: (1) their reduced use for domestic water-storage in large (> 1,000-litre) custom-made cement tanks which are their principal Aedes aegypti breeding sites and (2) their pupae/person index (PPI) values to below their established 0.5–1.5 PPI arbovirus transmission-threshold value, compared to matched neighbourhoods in the: (a) pre-economic boom (2004) period in Barranquilla and (b) economically-neglected seaport city of Buenaventura. The simple, accurate and robust water surface sweep-net/calibration factor or total count methods were used to determine the total Ae. aegypti pupae numbers in greater or less than 20-litre water-holding container types located ‘inside’ or ‘outside’ these neighbourhood premises. The women residents also participated in questionnaire-based responses about their domestic water supplies, water-storage and maintenance and mosquito life stages and disease transmission knowledge, to subsequently plan appropriate resident education programmes. Microsoft Excel 8.0 with OpenEpi was used to determine the samples sizes and the statistical values. Tapped water supplies to the three poor Barranquilla neighbourhoods were dramatically increased from 2004 to 2023 resulting in their residents significantly reducing their: (a) large cement water-storage tanks from 1 per 6.9 (2004) to 1 per 31.2 (2020) premises (z = 10.5: p = 0) and (b) PPI values to 0.16, 0.19 and 0.53 (mean: 0.29: 95% CI ± 0.4) in each study neighbourhood. In contrast, tapped water supplies remained inadequate in the Buenaventura neighborhoods, thereby resulting in their continued use of many large (> 1,000-litre) water-storage containers (Barranquilla: 1 per 31.2 and Buenaventura: 1 per 1.5 premises: z = − 9.26: p = 0), with unacceptably high 0.81, 0.88 and 0.99 PPI values in each study neighbourhood (mean 0.89: 95% CI ± 0.12). Improved tapped water supplies resulted in reduced numbers of large custom-made stoneware water-containers, as are employed by poor residents throughout the world, as well as their Ae. aegypti PPI transmission threshold values which, together with appropriate residents’ education programmes, are also urgently to reduce to prevent/reduce Ae. aegypti transmitted human diseases globally.

Few studies have investigated whether SARS-CoV-2 infections increase the incidence of dengue haemorrhagic fever/shock syndrome (DHF/DSS) and/or severe dengue (SD) in dengue virus (DENV)-infected patients. This study was performed on a site with high incidences of classical dengue, but relatively few DHF/DSS or SD cases as defined by the WHO 1997 or 2009 criteria, respectively. Clinical, haematological/biochemical, and viral diagnostic data were collected from febrile patients before, during, and after the COVID-19 epidemic to assess whether (a) DENV-infected patients with prior SARS-CoV-2 infections or (b) DENV-SARS-CoV-2-co-infected patients had increased incidences of SD/DHF/DSS using logistic regression and machine learning models. Higher numbers of DHF/DSS/SD occurred during the COVID-19 epidemic, particularly in males and 18–40-year-olds. Significantly increased symptoms in the DENV-SARS-CoV-2-co-infected cases were (a) haemoconcentration (p < 0.0009) and hypotension (p < 0.0005) (DHF/DSS and SD criteria), (b) thrombocytopenia and mucosal bleeding (DHF/DSS-criteria), (c) abdominal pain, persistent vomiting, mucosal bleeding, and thrombocytopenia (SD warning signs) and (d) dyspnoea, but without fluid accumulation. DENV-infected patients with prior SARS-CoV-2 infections had significantly increased incidences of thrombocytopenia (DHF/DSS-criteria) and/or abdominal pain and persistent vomiting and also thrombocytopenia (SD warning signs), but without significant haemoconcentration or hypotension. DENV-SARS-CoV-2 co-infections significantly increased the incidence of DHF/DSS/SD, while DENV-infected patients with prior SARS-CoV-2 infections displayed significantly increased incidences of thrombocytopenia (DHF/DSS-criteria) and three important SD warning signs, which are therefore very important for health workers/clinicians in assessing patients’ DHF/DSS/SD risk factors and planning their optimal therapies.

There are overlapping world distributions of the mosquito-borne dengue viruses (DENVs) and water-borne bacterial disease leptospirosis which cause large numbers of human infections and fatalities. As such, early differential diagnosis is required for appropriate early leptospirosis antibiotic therapy or DENV patient supportive care, but co-infections have also been reported. From 200 paired (S1 and S2) serum samples collected from suspected DENV infected patients, 70 (35%) were confirmed as ‘on-going’ infections by demonstrating > 4-fold S1 to S2 sample increased anti-DENV IgG and/or IgM ELISA titers. Of those, 8.57% (6/70) also displayed > 4-fold increased S1 to S2 sample titers in the ‘gold standard’ Leptospira spp. microscopic agglutination test (MAT) and paraformaldehyde (cell-membrane-impermeable fixative) treated leptospires in immunofluorescence assays (IFAs) due to cross-reactions with 68-72 and 38-42 KDa outer surface membrane antigens present on all Leptospira spp. serovars tested. While DENV-1, -2 or -3 serotypes were isolated from their S1 sera: a) Leptospira spp. could not be isolated from them, b) their S1 sera were all PCR-negative using a Leptospira spp.-specific gene target, and c) their S2 sera were all negative using a commercial anti- Leptospira spp. IgM ELISA. As such, we believe this is the first report of DENVs causing false positive reactions in the ‘gold standard’ Leptospira spp. MAT, IFAs, and immunoblot assays and which needs further assessments using patients’ samples which were possibly falsely reported as ‘DENV- Leptospira spp. co-infections’ in other studies, and to identify these 68-72 and 38-42 KDa Leptospira spp. outer surface membrane antigens by proteomic analyses.

Zika virus (ZIKV) is one of several examples of an unprecedented pandemic spread and against which there is currently no suitable vaccine or treatment. Here, we constructed and characterized recombinant baculovirus‐derived ZIKV‐like particles (Zika VLPs) to study ZIKV‐antibody interactions. These VLPs, uniquely consisted of the full‐length ZIKV capsid (C), pre‐membrane (prM), and envelope (E) proteins with either: a) the viral nonstructural NS2B and NS3 protease unit under one or two different promoters or b) an alternative host‐cell furin protease encoding cleavage sequence inserted between the C and prM genes, together with lobster tropomyosin leader and honeybee signal sequences with one promoter for increased extracellular secretion. All these Zika VLPs displayed typical virion morphology in transmission electron microscopic analysis when expressed in both insect (Sf9) and mammalian (HEK293T) cells and no uncleaved prM glycoprotein was detected, as are present on immature virions. The importance of glycosylation of the E glycoprotein was shown by the effects on both polyclonal and monoclonal antibody reactions after these N‐linked carbohydrate residues were disrupted by oxidation or enzymatic cleavage. Importantly, the construct which contained the host‐cell furin protease cleavage sequence together with a lobster tropomyosin leader and honeybee signal sequences under one promoter produced higher Zika VLP titers and protein concentrations and which can now be tested as a superior construct in multifunctional diagnostic (ELISA and neutralization/antibody‐dependent enhancement) assays and immunogenic assessments possibly leading to vaccine trials.

Chikungunya virus (CHIKV) and Zika virus (ZIKV) have recently emerged as globally important infections. This study aimed to explore the spatiotemporal heterogeneity in the occurrence of CHIKV and ZIKV outbreaks throughout the major international seaport city of Barranquilla, Colombia in 2014 and 2016 and the potential for clustering. Incidence data were fitted using multiple Bayesian Poisson models based on multiple explanatory variables as potential risk factors identified from other studies and options for random effects. A best fit model was used to analyse their case incidence risks and identify any risk factors during their epidemics. Neighbourhoods in the northern region were hotspots for both CHIKV and ZIKV outbreaks. Additional hotspots occurred in the southwestern and some eastern/southeastern areas during their outbreaks containing part of, or immediately adjacent to, the major circular city road with its import/export cargo warehouses and harbour area. Multivariate conditional autoregressive models strongly identified higher socioeconomic strata and living in a neighbourhood near a major road as risk factors for ZIKV case incidences. These findings will help to appropriately focus vector control efforts but also challenge the belief that these infections are driven by social vulnerability and merit further study both in Barranquilla and throughout the world’s tropical and subtropical regions.

Zika virus (ZIKV) constitutes an increasing public health problem. Previous studies have shown that CD8+ T cells play an important role in ZIKV-specific protective immunity. We have previously defined antigenic targets of the ZIKV-specific CD8+ T cell response in humans. In this study, we characterized the quality and phenotypes of these responses by a combined use of flow cytometry and transcriptomic methods, using PBMCs from donors deriving from different geographical locations collected in the convalescent phase of infection. We show that ZIKV-specific CD8+ T cells are characterized by a polyfunctional IFN-γ signature with upregulation of TNF-α, TNF receptors, and related activation markers, such as CD69, as well as a cytotoxic signature characterized by strong upregulation of GZMB and CRTAM. The signature is stable and not influenced by previous dengue virus exposure, geographical location, or time of sample collection postinfection. To our knowledge, this work elucidates the first in-depth characterization of human CD8+ T cells responding to ZIKV infection.

To evaluate the case report forms and times elapsed between the surveillance steps for dengue virus (DENV) infection in a large Colombian city before the emergence of other arbovirus epidemics. The descriptive epidemiology of DENV infection cases was analyzed from 2009 to 2013. The completeness of the case report forms filed at the Primary Units of Data Generation (PUDG) were evaluated, as well as the accuracy and suitability of the tests (PPV: positive predictive value). The average time-lags between each step were then calculated. There were 7.3, 12.38, 4.66, 6.25 and 29.9 annual cases of dengue infection per 10 000 inhabitants in 2009 to 2013, respectively. In this study, only 57.76% of the cases were classified correctly by the physicians and 26.32% of them were questioned about their home conditions and whether their family/friends had similar symptoms. Patients visited a clinic/hospital on average 4.76 days after developing symptoms and the health system was notified on average 1.75 days later, while 70.6% of them were reported within the one-day target period. There were only minor changes in case reporting times even during a DENV epidemic. Some (12.85%) of the case forms were later modified (average 16.7 days). In the period 2009-2013, the IgM confirmed PPV was 58.60%, while 20 mandatory criteria were absent on more than 25% of the forms. The system was accurate, simple, flexible, stable and acceptable, but a number of ways are suggested to improve this case detection and reporting system.