Prospective Study of Leptospirosis Transmission in an Urban Slum Community: Role of Poor Environment in Repeated Exposures to the Leptospira Agent

Abstract

BackgroundLeptospirosis has emerged as an urban health problem as slum settlements have rapidly spread worldwide and created conditions for rat-borne transmission. Prospective studies have not been performed to determine the disease burden, identify risk factors for infection and provide information needed to guide interventions in these marginalized communities.Methodology/Principal FindingsWe enrolled and followed a cohort of 2,003 residents from a slum community in the city of Salvador, Brazil. Baseline and one-year serosurveys were performed to identify primary and secondary Leptospira infections, defined as respectively, seroconversion and four-fold rise in microscopic agglutination titers. We used multinomial logistic regression models to evaluate risk exposures for acquiring primary and secondary infection. A total of 51 Leptospira infections were identified among 1,585 (79%) participants who completed the one-year follow-up protocol. The crude infection rate was 37.8 per 1,000 person-years. The secondary infection rate was 2.3 times higher than that of primary infection rate (71.7 and 31.1 infections per 1,000 person-years, respectively). Male gender (OR 2.88; 95% CI 1.40–5.91) and lower per capita household income (OR 0.54; 95% CI, 0.30–0.98 for an increase of $1 per person per day) were independent risk factors for primary infection. In contrast, the 15–34 year age group (OR 10.82, 95% CI 1.38–85.08), and proximity of residence to an open sewer (OR 0.95; 0.91–0.99 for an increase of 1 m distance) were significant risk factors for secondary infection.Conclusions/SignificanceThis study found that slum residents had high risk (>3% per year) for acquiring a Leptospira infection. Re-infection is a frequent event and occurs in regions of slum settlements that are in proximity to open sewers. Effective prevention of leptospirosis will therefore require interventions that address the infrastructure deficiencies that contribute to repeated exposures among slum inhabitants.

Knowledge, Attitude and Practices towards Leptospirosis among Lakeshore Communities of Calamba and Los Baños, Laguna, Philippines

“…This study found that leptospirosis prevention practice scores increased significantly with increasing age and household income among non-agricultural workers. The risk of leptospirosis infection is commonly reported among younger and low-income groups [57][58][59]. Considering that younger and lower-income groups were less likely to engage in leptospirosis prevention practices, a more concerted effort of changing the health behavior of these groups would be beneficial in reducing the risk and potential economic burden of leptospirosis.…”

Hypertension in a Brazilian Urban Slum Population

“…21,26 In 2003, Salvador's Oswaldo Cruz Foundation (FIOCRUZ) established a study site within this community for a cohort study of urban leptospirosis. [29][30][31] A household census by FIOCRUZ at that time identified 14,867 residents in 3068 households within the 0.46 km 2 study area.…”

Comportamiento Epidemiológico De La Leptospirosis Humana Y Animal en La Provincia De Villa Clara, Cuba

“…Concuerdan además nuestros resultados con los obtenidos por Céspedes et al (2003) quienes al identificar factores de riesgos en la población humana de la provincia Manu, Perú, plantearon que la infección por Lepstospira presentó una tendencia homogénea entre los distintos grupos etarios, aunque el número de seropositivos fue mayor en las personas de edad laboral. Según Felzemburgh et al (2014) aunque el género masculino no fue identificado como un factor de riesgo de infección por Leptospira en un estudio de cohorte realizado en un área rural, los varones tienen un riesgo significativamente superior para adquirir leptopirosis. De acuerdo con Alavi & Khoshkho (2014) en las recientes décadas la leptospirosis ha sido considerada como una enfermedad infecciosa emergente que constituye un problema importante de salud pública a nivel mundial, que se presenta en ambientes urbanos, así como también en regiones rurales.…”