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)

Survival and Speed of Escherichia coli Infiltration in a Hydromorphic Soil in Wet Tropical Zone.

Aims: Untreated wastewater is usually used for crop irrigation in developing countries; however it contains a lot of pathogenic bacteria. This study was carried out to determine the fate of E. coli contained in wastewater in a hydromorphic soil. Study Design: Environmental microbiology Place and Duration of the Study: This study was carried out in the experimental field of the Dschang University, during the dry season (November 2011- Mars 2012) and the rainy season (June 2012-September 2012). Methodology: Six plots of 4 m2 each were tilled in 400 m2 surface area in the dry and in the rainy seasons. Wastewater was collected from the experimental wastewater treatment station in the University of Dschang; it was applied on three plots, and three other plots were used as controls. Once every week, soil samples were taken on the surface (0 - 10 cm), in the medium (20 - 30 cm) and at the water table level (40 - 50 cm). Levels of E. coli in soil samples were determined on “Lactose Tergitol® 7 Agar with TTC” medium, and midbiochemical confirmation tests were carried out (tests of indol, Simmons citrate, gas production, mobility, fermentation of mannitol, glucose and lactose). Results: In the rainy season, E. coli was detected on the soil surface until the 112th day, while in the dry season detection did not exceed the 63rd day. E. coli was detected in the deeper layers of the soil (20 - 30 and 40 - 50 cm) from the 14th and the 70th day respectively. This helps to estimate the speed of vertical migration to be between 5 and 18 mm per day. Conclusion: E. coli bacteria contained in urban wastewater survive for a long-time in hydromorphic soils and reach significant depths, and can consequently pose serious problems of public health.

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.