Spatio-Temporal Modeling of Zika and Dengue Infections within Colombia.

The aim of this study is to estimate the parallel relative risk of Zika virus disease (ZVD) and dengue using spatio-temporal interaction effects models for one department and one city of Colombia during the 2015⁻2016 ZVD outbreak. We apply the integrated nested Laplace approximation (INLA) for parameter estimation, using the epidemiological week (EW) as a time measure. At the departmental level, the best model showed that the dengue or ZVD risk in one municipality was highly associated with risk in the same municipality during the preceding EWs, while at the city level, the final model selected established that the high risk of dengue or ZVD in one census sector was highly associated not only with its neighboring census sectors in the same EW, but also with its neighboring sectors in the preceding EW. The spatio-temporal models provided smoothed risk estimates, credible risk intervals, and estimation of the probability of high risk of dengue and ZVD by area and time period. We explore the intricacies of the modeling process and interpretation of the results, advocating for the use of spatio-temporal models of the relative risk of dengue and ZVD in order to generate highly valuable epidemiological information for public health decision making.

Relative risk estimation of dengue disease at small spatial scale.

BACKGROUND: Dengue is a high incidence arboviral disease in tropical countries around the world. Colombia is an endemic country due to the favourable environmental conditions for vector survival and spread. Dengue surveillance in Colombia is based in passive notification of cases, supporting monitoring, prediction, risk factor identification and intervention measures. Even though the surveillance network works adequately, disease mapping techniques currently developed and employed for many health problems are not widely applied. We select the Colombian city of Bucaramanga to apply Bayesian areal disease mapping models, testing the challenges and difficulties of the approach. METHODS: We estimated the relative risk of dengue disease by census section (a geographical unit composed approximately by 1-20 city blocks) for the period January 2008 to December 2015. We included the covariates normalized difference vegetation index (NDVI) and land surface temperature (LST), obtained by satellite images. We fitted Bayesian areal models at the complete period and annual aggregation time scales for 2008-2015, with fixed and space-varying coefficients for the covariates, using Markov Chain Monte Carlo simulations. In addition, we used Cohen's Kappa agreement measures to compare the risk from year to year, and from every year to the complete period aggregation. RESULTS: We found the NDVI providing more information than LST for estimating relative risk of dengue, although their effects were small. NDVI was directly associated to high relative risk of dengue. Risk maps of dengue were produced from the estimates obtained by the modeling process. The year to year risk agreement by census section was sligth to fair. CONCLUSION: The study provides an example of implementation of relative risk estimation using Bayesian models for disease mapping at small spatial scale with covariates. We relate satellite data to dengue disease, using an areal data approach, which is not commonly found in the literature. The main difficulty of the study was to find quality data for generating expected values as input for the models. We remark the importance of creating population registry at small spatial scale, which is not only relevant for the risk estimation of dengue but also important to the surveillance of all notifiable diseases.

Bayesian dynamic modeling of time series of dengue disease case counts.

The aim of this study is to model the association between weekly time series of dengue case counts and meteorological variables, in a high-incidence city of Colombia, applying Bayesian hierarchical dynamic generalized linear models over the period January 2008 to August 2015. Additionally, we evaluate the model's short-term performance for predicting dengue cases. The methodology shows dynamic Poisson log link models including constant or time-varying coefficients for the meteorological variables. Calendar effects were modeled using constant or first- or second-order random walk time-varying coefficients. The meteorological variables were modeled using constant coefficients and first-order random walk time-varying coefficients. We applied Markov Chain Monte Carlo simulations for parameter estimation, and deviance information criterion statistic (DIC) for model selection. We assessed the short-term predictive performance of the selected final model, at several time points within the study period using the mean absolute percentage error. The results showed the best model including first-order random walk time-varying coefficients for calendar trend and first-order random walk time-varying coefficients for the meteorological variables. Besides the computational challenges, interpreting the results implies a complete analysis of the time series of dengue with respect to the parameter estimates of the meteorological effects. We found small values of the mean absolute percentage errors at one or two weeks out-of-sample predictions for most prediction points, associated with low volatility periods in the dengue counts. We discuss the advantages and limitations of the dynamic Poisson models for studying the association between time series of dengue disease and meteorological variables. The key conclusion of the study is that dynamic Poisson models account for the dynamic nature of the variables involved in the modeling of time series of dengue disease, producing useful models for decision-making in public health.

Etiología y estacionalidad de las infecciones respiratorias viralesen menores de cinco años en Bucaramanga, Colombia / Etiology and seasonality of viral respiratory infections in children under 5 years of age in Bucaramanga, Colombia / Etiologia e sazonalidade das infeções respiratórias virais em menores de cinco anos em Bucaramanga, Colômbia

RESUMEN Objetivo: describir los virus asociados con infección respiratoria en niños en Bucaramanga. Materiales y métodos: estudio descriptivo con recolección prospectiva. Los participantes fueron menores de 5 años con fiebre y síntomas respiratorios de máximo 5 días de duración atendidos en dos instituciones de Bucaramanga. Se registraron los datos sociodemográficos, los antecedentes y los hallazgos del examen físico. Las muestras obtenidas por hisopado nasofaríngeo se procesaron para 15 virus respiratorios mediante una prueba múltiplex de reacción en cadena de polimerasa. Resultados: entre diciembre de 2012 y noviembre de 2013, se incluyó a 215 menores de 5 años (edad promedio: 14 meses). La positividad para al menos un virus fue 72 % y se identificó coinfección en 8,5 %. Los virus identificados con mayor frecuencia en las estaciones secas fueron el sincitial respiratorio, rinovirus A/B/C y metapneumovirus, mientras que en las estaciones lluviosas fueron parainfluenza 1/2/3, virus sincitial respiratorio e influenza. Se hallaron coronavirus y bocavirus por primera vez en este grupo de edad en Colombia. Conclusiones: una amplia variedad de virus respiratorios afecta a los niños en Bucaramanga y su ocurrencia a lo largo del año difiere de la de otras regiones de Colombia.

SUMMARY Objective: To describe viruses associated with respiratory infection in children in Bucaramanga, the main city in northeastern Colombia. Materials and methods: Descriptive study with prospective collection. Participants were children under 5 years with respiratory symptoms for a maximum of 5 days, treated at two institutions of Bucaramanga. Demographic data, medical and perinatal history and initial physical examination findings were recorded. Samples obtained with nasopharyngeal swabs were processed for 15 respiratory viruses by multiplex reaction polymerase chain test. Results: Between December 2012 and November 2013, 215 children less than 5 years (mean age 14 months) were enrolled. Positivity to at least one virus was 72 % and co-infection was detected in 8.5 %. The most frequently identified viruses in dry seasons were respiratory syncytial virus, rhinovirus A/B/C and metapneumovirus, while in the rainy seasons they were parainfluenza 1/2/3, respiratory syncytial virus and influenza. Coronavirus and bocavirus were identified for the first time in this age group in Colombia. Conclusions: A wide variety of viruses affects children in this area of Colombia, and their occurrence throughout the year is different from that reported in other regions of the country.

RESUMO Objetivo: Descrever os vírus associados com infecção respiratória em crianças em Bucaramanga. Materiais e métodos: estudo descritivo com recolecção prospectiva. Os participantes foram menores de 5 anos com febre e sintomas respiratórios de máximo 5 dias de duração atendidos em duas instituições de Bucaramanga. Se registraram os dados sócio-demográficos, os antecedentes e os resultados do exame físico. As amostras obtidas por hissopado nasofaringe se processaram para 15 vírus respiratórios mediante uma prova múltipla de reação em cadeia de polimerase. Resultados: entre dezembro de 2012 e novembro de 2013, se incluiu a 215 menores de 5 anos (idade em média: 14 meses). A positividade para pelo menos um vírus foi 72 % e se identificou co-infecção em 8,5 %. Os vírus identificados com maior frequência nas estações secas foram o sincitial respiratório, rinovírus A/B/C e metapneumovírus, enquanto que nas estações chuvosas foram parainfluenza 1/2/3, vírus sincitial respiratório e influenza. Se encontraram coronavírus e bocavírus por primeira vez neste grupo de idade na Colômbia. Conclusões: uma ampla variedade de vírus respiratórios afeta às crianças em Bucaramanga e sua ocorrência ao longo do ano difere de outras regiões da Colômbia.

Etiología viral de infección respiratoria aguda en niños menores de 5 años en las provincias Comunera y García Rovira de Santander / Etiology of acute respiratory infection in children under 5 years in the provinces Comunera and García Rovira of Santander

Introducción: La infección respiratoria aguda es una causa importante de morbimortalidad en menores de cinco años en los municipios de las provincias de Santander. La etiología viral en esos municipios no es bien conocida. Objetivo: El objetivo del estudio fue determinar la etiología viral de la infección respiratoria aguda en menores de cinco años en las provincias Comunera y García Rovira del departamento de Santander entre diciembre de 2012 y diciembre de 2013. Materiales y métodos: Estudio descriptivo en población usuaria de servicios de urgencias. Se obtuvieron muestras por hisopado nasofaríngeo y se realizó amplificación por reacción en cadena de polimerasa con el test Seeplex® RV15 OneStep ACE Detection, multiplex para 15 virus. Resultados: Participaron 64 niños, 57,8% niños de sexo masculino. El 26,6%, de los niños eran menores de un año. La positividad para virus fue del 37,5% de las muestras. El 75% de las muestras positivas fueron de la provincia Comunera y 25% de la provincia de García Rovira. Hubo co-infección por dos virus en 8,3% de las muestras positivas. Los virus más identificados fueron Rhinovirus (29%), Parainfluenza 4 (20,8%) e Influenza (12,5%). También se identificó Coronavirus, Adenovirus, Virus Sincitial Respiratorio, Metapneumovirus y otros virus Parainfluenza. Conclusiones: En las dos provincias de Santander evaluadas circula una amplia cantidad de virus respiratorios en menores de cinco años. El Rhinovirus fue identificado como el más frecuente. Se encontró presencia de Metapneumovirus y Coronavirus humano.

Introduction: Acute respiratory infection is a major cause of morbidity and mortality in children under 5 years in Santander (Colombia). Viral etiology in municipalities from this department is not well known. Objective: To determine the viral etiology of acute respiratory infection in children under five years in the provinces Comunera and García Rovira (Santander) from December 2012 to December 2013. Methodology: Descriptive study in pediatric population who attended the emergency services studied. Nasopharyngeal swab samples were obtained and a polymerase chain reaction was performed with Seeplex® OneStep RV15 ACE Detection, which is a multiplex test for 15 virus. Results: 64 children were enrolled, 57,8% being boys. 26.6% of participants were under one year. Virus positivity was present in 37.5% of the samples and 75% of the positive samples were from the province Comunera. Besides, 8.3% from positive samples were co-infected with two viruses. The most common virus were Rhinovirus (29%), Parainfluenza 4 (20.8%) and influenza (12.5%). Coronavirus, Adenovirus, respiratory syncytial virus, Metapneumovirus and other Parainfluenza virus were also identified. Conclusions: There is a wide circulation of respiratory virus in children under five in these two provinces of Santander (Colombia). Rhinovirus was the most frequent. Human Metapneumovirus and Coronavirus were also found.

Evaluación de la contracción por polimerización de dos técnicas de aplicación para resinas / Evaluation of the polymerization shrinkage of two composite resin placement techniques

El fenómeno de contracción por polimerización que presenta el material restaurador en la superficie dental, hace que se creen espacios en los que se presenta microfiltración. El propósito de este estudio fue compara dos clases de resinas compuestas (II y IV generación), realizando en cada una de ellas dos técnicas de aplicación, una con técnica en bloque (B) y otra con aplicación progresiva (AP), por incrementos de 1 mm. Para este estudio se tomó una muestra de 40 troqueles cada uno, para la colocación de la resina compuesta así: 10 (AP) II generación, 10 (B) II generación, 10 (AP) IV generación y 10 (B) IV generación. Una vez aplicada la resina se polimerizaron cada uno de los grupos por medio del sistema de luz Triad, utilizando 1 minuto para las resinas colocadas con técnica en bloque y 1 minuto por cada incremento en los grupos de aplicación progresiva. A los troqueles se les realió un corte sagital para poder observar y medir la contracción en los ángulos axiopulpar y axiogingival de la cajuela mesial, por medio del microscopio electrónico de barrido (SEM 505 de Philips). Los resultados obtenidos en dichas dimensiones se registraron en tablas. Este estudio mostró que la contracción se presenta en mayor proporción en las resinas de la II generación con las técnica de aplicación en bloque. Estadísticamente, no se encontraron diferencias significativas entre las dos técnicas de aplicación, pero entre las resinas sí