Incidencia de la humedad relativa en la transmisión de la COVID-19 / Impact of relative humidity on COVID-19 transmission

Introducción: El nuevo patógeno SARS-CoV-2 presenta una rápida propagación, y es el causante de la enfermedad del Coronavirus 2019 (COVID-19). Dado que este virus es reciente, el aumento de los casos de la enfermedad COVID-19 ha sido una gran amenaza, a lo que le ha sumado la no existencia de información contundente sobre la enfermedad, su transmisión, y su relación con las distintas variables ambientales. Objetivo: Determinar la incidencia de la humedad relativa en la transmisión de la COVID-19 en las regiones tropicales de Colombia. Métodos: Se analizaron los datos de humedad relativa y número de contagios diarios de COVID-19 de siete ciudades de Colombia ubicadas en la Región Caribe (Barranquilla y Sincelejo), Región Andina (Medellín, Bucaramanga, Armenia y Cúcuta), además de la Región Amazónica (Leticia). Se utilizó un modelo logístico generalizado para analizar los datos existentes y diseñar las curvas epidemiológicas. Resultados: Para todas las ciudades, de acuerdo con el modelo se encontraron altas correlaciones entre la humedad relativa (variable observada) y COVID-19 (variable predicha) con un R2 > 0,90. No obstante, se determinó si existía asociación entre las variables comparando el valor p con el nivel de significancia α del 0,05, se encontró una asociación estadísticamente significativa en las ciudades de Leticia, Barranquilla y Cúcuta. Conclusiones: Los resultados indican que existe una relación directa entre la humedad relativa y la transmisión de COVID 19 en regiones tropicales de Colombia. De ahí que se plantee que el estudio aporta una herramienta importante para la toma de decisiones de las instituciones a cargo del control de la enfermedad, como los gobiernos nacionales y locales(AU)

Introduction: The new pathogen SARS-CoV-2 presents a rapid spread, and is the cause of the Coronavirus disease 2019 (COVID-19). Given that this virus is recent, the increase in cases of the COVID-19 disease has been a great threat, to which has been added the lack of conclusive information about the disease, its transmission, and its relationship with the different environmental variables. Objective: To determine the incidence of relative humidity in the transmission of COVID-19 in the tropical regions of Colombia. Methods: Relative humidity data and number of daily COVID-19 infections from seven cities in Colombia located in the Caribbean Region (Barranquilla and Sincelejo), Andean region (Medellín, Bucaramanga, Armenia and Cúcuta), as well as the Amazon Region (Leticia) were analyzed. A generalized logistic model was used to analyze existing data and design epidemiological curves. Results: For all cities, according to the model, high correlations were found between relative humidity (observed variable) and COVID-19 (predicted variable) with an R2 > 0.90. However, it was determined if there was an association between the variables by comparing the p-value with the level of significance α 0.05, a statistically significant association was found in the cities of Leticia, Barranquilla and Cúcuta. Conclusions: The results indicate that there is a direct relationship between relative humidity and the transmission of COVID 19 in tropical regions of Colombia. Hence, it is proposed that the study provides an important tool for the decision-making of the institutions in charge of the control of the disease, such as national and local governments(AU)

Anaerobic microbiota: spatial-temporal changes in the sediment of a tropical coastal lagoon with ephemeral inlet in the Gulf of Mexico / Microbiota anaerobia: cambios espacio-temporales en el sedimento de una laguna costera tropical con boca efímera en el Golfo de México

Abstract:Sulfate-reducing bacteria (SRB) and methanogenic archaea (MA) share common niches in coastal sediments during the terminal phases of the anaerobic mineralization of organic matter. The purpose of this study was to analyze the spatial - temporal variation of SRB and MA in the sediments of a tropical coastal lagoon with ephemeral inlet (La Mancha, Veracruz, Gulf of Mexico) and its relationship with environmental changes. A total of 24 sediment samples were collected during the dry (April, May), rainy (July, September) and Northern (November, February) seasons in the period 2013-2014. Microbiological analyses included the quantification of the viable SRB and MA with different substrates, as well as mineralization experiments to determine the effect of sulfate on acetate oxidation. The analyzed environmental variables in the sediments included: temperature, pH, Eh, salinity, sulfates, H2S, volatile solids, carbohydrates, and granulometric characteristics. Major changes occurred between the dry and rainy seasons. During the dry season, sulfate-reducing abundance was significantly greater with lactate (8.3x105 - 1.2x107 cells / g) and propionate (1.8x105 - 6.6x106 cells / g) as substrates, while the MA that use methanol were dominant (4.2x105 - 9.1x106 cells / g). In contrast, during the rainy season, hydrogenophylic (2.6x105 - 8.3x106 cells/g) and acetoclastic (5.4x105-6.4x106 cells / g) MA increased significantly and SRB decreased in the analyzed substrates. An apparent competition for acetate was observed, with a greater oxidation in the media with sulfates in the dry season (0.06 mM acetate / g sediment / day), and a greater oxidation in the media without sulfates in the rainy season (0.02 mM acetate / g sediment / day). SRB and MA were present throughout the sediment column, however SRB dominated in the first centimeters of the sediment while MA were abundant in deeper layers. In conclusion, SRB and MA together played a role in the mineralization of organic matter in the sediments of La Mancha lagoon, with sulfate-reduction dominating in the dry season (closed inlet) and methanogenesis during the rainy season (open inlet). Changes in rainfall and river input in this lagoon significantly affect salinity and sulfate content, the main factors that regulate the dynamics of SRB and MA in the sediments. Rev. Biol. Trop. 64 (4): 1759-1770. Epub 2016 December 01.

Resumen:Las bacterias sulfatorreductoras (BSR) y las arqueas metanogénicas (AM) comparten nichos comunes en los sedimentos costeros durante las fases terminales de la mineralización anaerobia de la materia orgánica. El objetivo del presente estudio fue analizar la variación espacio-temporal de las BSR y AM en los sedimentos de una laguna costera tropical con una boca efímera (La Mancha, Veracruz, Golfo de México) y su relación con los cambios ambientales. Un total de 24 muestras de sedimentos fueron recolectadas en las temporadas de secas (abril, mayo), lluvias (julio, septiembre) y nortes (noviembre, febrero) en el periodo 2013 - 2014. Los análisis microbiológicos incluyeron la cuantificación de las BSR y AM viables con diferentes sustratos, así como experimentos de mineralización para determinar el efecto de los sulfatos en la oxidación del acetato. Las variables ambientales analizadas en los sedimentos incluyeron la temperatura, pH, Eh, salinidad, sulfatos, H2S, sólidos volátiles, carbohidratos y las características granulométricas. Los principales cambios se presentaron entre las estaciones de secas y lluvias. En la temporada de secas la abundancia sulfatorreductora fue significativamente superior con lactato (8.3x105 - 1.2x107 células / g) y propionato (1.8x105 - 6.6x106 células / g) como sustratos, mientras que las AM que emplean metanol dominaron (4.2x105 - 9.1x106 células / g). Por el contrario, en la época de lluvias aumentaron significativamente las AM hidrogenofílicas (2.6x105-8.3x106 células / g) y acetoclásticas (5.4x105-6.4x106 células / g), disminuyendo las BSR con los sustratos analizados. Se determinó una competencia aparente por el acetato. Su oxidación fue mayor en los medios con presencia de sulfatos en las temporadas de secas (0.06 mM acetato / g sedimento / día), mientras que aumentó en los medios sin sulfatos en la época de lluvias (0.02 mM acetato / g sedimento / día). Las BSR y las AM estuvieron presentes a lo largo de la columna sedimentaria; sin embargo, las BSR dominaron en los primeros centímetros del sedimento y las AM abundaron a mayor profundidad. En conclusión las BSR y AM participaron de manera conjunta en la mineralización de la materia orgánica en los sedimentos de la laguna de La Mancha, dominando la sulfatorreducción en la temporada de secas (boca cerrada) y la metanogénesis en la época de lluvias (boca abierta). Los cambios en el aporte fluvial y la precipitación en esta laguna afectaron significativamente la salinidad y el contenido de sulfatos, siendo los principales factores que regularon la dinámica de las BSR y AM en los sedimentos.

Seasonality of suicide in the city of Sao Paulo, Brazil, 1979-2003 / Sazonalidade do suicídio na cidade de São Paulo, Brasil, 1979-2003

OBJECTIVE: To evaluate suicide seasonality in the city of São Paulo within an urban area and tropical zone. METHOD: Suicides were evaluated using the chi-square test and analysis of variance (ANOVA) by comparing monthly, quarterly and half-yearly variations, differentiating by gender. Analyses of time series were carried out using the autocorrelation function and periodogram, while the significance level for seasonality was confirmed with the Fisher's test. RESULTS: The suicides of the period between 1979 and 2003 numbered 11,434 cases. Differences were observed in suicides occurring in Spring and Autumn for the total sample (ANOVA: p-value = 0.01), and in the male sample (ANOVA: p-value = 0.02). For the analysis of time series, seasonality was significant only for the period of 7 months in the male sample (p-value = 0.04). DISCUSSION: In this study, no significant seasonal differences were observed in the occurrences of suicides, with the exception of the male sample. The differences observed did not correspond with the pattern described in studies carried out in temperate zones. Some of the climatic particularities of the tropical zone might explain the atypical pattern of seasonality of suicides found in large populations within an urban area and tropical zone.

OBJETIVO: Avaliar a sazonalidade do suicídio na cidade de São Paulo, uma área urbana em zona tropical. MÉTODO: Os suicídios foram avaliados pelo teste de qui-quadrado e análise de variância (ANOVA), comparando variações mensais, trimestrais e semestrais, diferenciando por gênero. Também foi realizada a análise de séries temporais, utilizando a função de autocorrelação e periodograma, além da confirmação, com o teste de Fisher de significância para sazonalidade. RESULTADOS: Os suicídios do período entre 1979 e 2003 totalizaram 11.434 casos. Foram observadas diferenças apenas nos suicídios ocorridos na primavera e outono na amostra total (ANOVA: p-valor = 0,01), e na amostra para o sexo masculino (ANOVA: p-valor = 0,02). Pela análise de séries temporais, a sazonalidade foi significativa apenas para o período de sete meses, na amostra para o sexo masculino (p-valor = 0,04). DISCUSSÃO: Neste estudo não foram observadas diferenças sazonais significativas na ocorrência de suicídios, com exceção da amostra masculina. Tais diferenças não correspondem ao padrão descrito nos estudos realizados em zona temperada. Algumas das particularidades climáticas da zona tropical poderiam explicar o padrão atípico de sazonalidades de suicídios em uma grande população de área urbana e zona tropical.