Seroprevalence of human leptospirosis in a rural community from Tandil, Argentina. Assessment of risk factors and spatial analysis / Seroprevalencia de leptospirosis humana en una comunidad rural del partido de Tandil (Argentina). Identificación de los factores de riesgo y del análisis espacial

Abstract Leptospirosis is a neglected zoonosis that is widely distributed in the world. Although it is endemic in Argentina, prevalence remains unknown. The aims of the study were: (i) to determine the prevalence of leptospirosis in humans from a rural community in Tandil Argentina, (ii) to identify infecting Leptospira spp. serogroups, (iii) to identify factors associated with the infection, (iv) to estimate the population attributable fraction (PAF) of the risk factors and (v) to determine the spatial patterns of disease presentation and related risk factors. Blood samples from 202 participants were collected. A survey was conducted to obtain clinical and epidemiological data. Serological testing was performed by the microscopic agglutination test (MAT). Univariate and multivariate methods were applied to evaluate associations. Spatial clusters were investigated for seroprevalence and risk factors. Antibodies were found in 32.2% of participants (95% CI: 25.8-39.1). The most prevalent serogroup was Hebdomadis followed by Sejroe; Icterohaemorrhagiae; Tarassovi and Canicola. Living at lower altitudes (OR: 13.04; 95% CI: 2.60-65.32); not having access to water supply network (OR: 2.95; 95% CI: 1.30-6.69); living close to flooded streets (OR: 2.94; 95% CI: 1.14-7.69) and practicing water sports (OR: 3.12; 95% CI: 1.12-8.33) were associated with seropositivity. Factors related with housing characteristics, services and infrastructure had the higher PAF (from 17% to 81%). A spatial cluster with higher rates of positivity and of the main risk factors was determined. This work contributes useful data for specific preventive measures that should be implemented for the control of the disease.

Resumen La leptospirosis es una enfermedad desatendida, ampliamente distribuida a nivel mundial. Aunque es endémica en Argentina, su prevalencia es desconocida. Los objetivos de este estudio fueron los siguientes: (i) determinar la prevalencia de leptospirosis humana en comunidades rurales del partido de Tandil (Argentina), (ii) identificar serogrupos infectantes de Leptospira spp., (iii) identificar factores de riesgo asociados, (iv) estimar la fracción atribuible poblacional (FAP) de los factores de riesgo y (v) determinar los patrones espaciales de la enfermedad y de los factores de riesgo. Se tomaron muestras de sangre a 202 personas, y se registró información clínica y epidemiológica. El diagnóstico se realizó por microaglutinación (MAT). Para evaluar asociaciones, se utilizaron métodos univariados y multivariados. Se estudiaron clusters espaciales de la seroprevalencia y de los factores de riesgo. El 32,2% de los participantes (IC 95%: 25,8-39,1) presentaron anticuerpos. Los serogrupos más prevalentes fueron Hebdomadis, Sejroe, Icterohaemorrhagiae, Tarassovi y Canicola. Vivir a menores altitudes (OR: 13,04; IC 95%: 2,60-65,32) y cerca de calles inundables (OR: 2,94; IC 95%: 1,14-7,69), la falta de acceso a agua de red (OR: 2,95; IC 95%: 1,30-6,69) y la práctica de deportes acuáticos (OR: 3,12; IC 95%: 1,12-8,33) estuvieron asociados con la seropositividad. Factores relacionados con las características de las viviendas, los servicios y la infraestructura tuvieron mayor proporción de FAP (17 al 81%). Se encontró un área de mayor riesgo de presentación de individuos seropositivos y de los principales factores de riesgo. Este trabajo provee información útil para generar medidas preventivas específicas que podrían ser aplicadas para controlar esta enfermedad.

Seroprevalence of human leptospirosis in a rural community from Tandil, Argentina. Assessment of risk factors and spatial analysis.

Leptospirosis is a neglected zoonosis that is widely distributed in the world. Although it is endemic in Argentina, prevalence remains unknown. The aims of the study were: (i) to determine the prevalence of leptospirosis in humans from a rural community in Tandil Argentina, (ii) to identify infecting Leptospira spp. serogroups, (iii) to identify factors associated with the infection, (iv) to estimate the population attributable fraction (PAF) of the risk factors and (v) to determine the spatial patterns of disease presentation and related risk factors. Blood samples from 202 participants were collected. A survey was conducted to obtain clinical and epidemiological data. Serological testing was performed by the microscopic agglutination test (MAT). Univariate and multivariate methods were applied to evaluate associations. Spatial clusters were investigated for seroprevalence and risk factors. Antibodies were found in 32.2% of participants (95% CI: 25.8-39.1). The most prevalent serogroup was Hebdomadis followed by Sejroe; Icterohaemorrhagiae; Tarassovi and Canicola. Living at lower altitudes (OR: 13.04; 95% CI: 2.60-65.32); not having access to water supply network (OR: 2.95; 95% CI: 1.30-6.69); living close to flooded streets (OR: 2.94; 95% CI: 1.14-7.69) and practicing water sports (OR: 3.12; 95% CI: 1.12-8.33) were associated with seropositivity. Factors related with housing characteristics, services and infrastructure had the higher PAF (from 17% to 81%). A spatial cluster with higher rates of positivity and of the main risk factors was determined. This work contributes useful data for specific preventive measures that should be implemented for the control of the disease.

Estimation of methane emission from an urban wastewater treatment plant applying inverse Gaussian model.

The methane (CH4) emissions from urban sources are increasing, and they depend on the processes and technologies applied in each one. Thus, studying them individually to quantify their emissions and understand their behavior to design CH4 mitigation strategies is meaningful. Although many studies have been carried out in different cities worldwide, the complex methodologies and technologies applied are not readily available in developing countries. The main objective of this work is to apply a simple and inexpensive methodology to collect air samples in urban areas using syringes with a three-way stopcock. Considering the baseline concentration in different urban zones, the WWTP contribution to atmospheric CH4 concentration was assessed. Moreover, it was possible to estimate the CH4 emission rate from the source by applying the inverse Gaussian model. The atmospheric CH4 concentrations inside and around the WWTP varied from 2.04 to 32.78 ppm. Most of the highest concentrations were found inside the WWTP; however, high concentrations were found up to 500 m from its center. The values in the urban zones were between 2.06 and 3.52 ppm, consistently higher in the area with the highest population density. Finally, considering the WWTP as a single source and according to the operational and atmospheric conditions during the studied period, the mean CH4 emission rate from this source was 2.08E + 04 µg s-1. The proposed sampling methodology could be applied to estimate CH4 emission rates from fixed sources in areas with overlapping sources.