Linking rattiness, geography and environmental degradation to spillover Leptospira infections in marginalised urban settings: An eco-epidemiological community-based cohort study in Brazil

Background: Zoonotic spillover from animal reservoirs is responsible for a significant global public health burden, but the processes that promote spillover events are poorly understood in complex urban settings. Endemic transmission of Leptospira, the agent of leptospirosis, in marginalised urban communities occurs through human exposure to an environment contaminated by bacteria shed in the urine of the rat reservoir. However, it is unclear to what extent transmission is driven by variation in the distribution of rats or by the dispersal of bacteria in rainwater runoff and overflow from open sewer systems. Methods: We conducted an eco-epidemiological study in a high-risk community in Salvador, Brazil, by prospectively following a cohort of 1401 residents to ascertain serological evidence for leptospiral infections. A concurrent rat ecology study was used to collect information on the fine-scale spatial distribution of 'rattiness', our proxy for rat abundance and exposure of interest. We developed and applied a novel geostatistical framework for joint spatial modelling of multiple indices of disease reservoir abundance and human infection risk. Results: The estimated infection rate was 51.4 (95%CI 40.4, 64.2) infections per 1000 follow-up events. Infection risk increased with age until 30 years of age and was associated with male gender. Rattiness was positively associated with infection risk for residents across the entire study area, but this effect was stronger in higher elevation areas (OR 3.27 95% CI 1.68, 19.07) than in lower elevation areas (OR 1.14 95% CI 1.05, 1.53). Conclusions: These findings suggest that, while frequent flooding events may disperse bacteria in regions of low elevation, environmental risk in higher elevation areas is more localised and directly driven by the distribution of local rat populations. The modelling framework developed may have broad applications in delineating complex animal-environment-human interactions during zoonotic spillover and identifying opportunities for public health intervention

Appendix C. The response of zooplankton community composition to different treatments.

The response of zooplankton community composition to different treatments

Appendix B. Interactive effect of warming and predation during winter.

Interactive effect of warming and predation during winter

Appendix G. Linear mixed effects model summary statistics for the loge-transformed mean zooplankton community body size.

Linear mixed effects model summary statistics for the loge-transformed mean zooplankton community body size

Appendix E. Phytoplankton genus richness as a function of treatment combinations.

Phytoplankton genus richness as a function of treatment combinations

Appendix H. Summary statistics for the redundancy analysis (RDA) on Hellinger-transformed phytoplankton taxonomic composition data.

Summary statistics for the redundancy analysis (RDA) on Hellinger-transformed phytoplankton taxonomic composition data

A Two-Year Ecological Study of Norway Rats (Rattus norvegicus) in a Brazilian Urban Slum

Submitted by Ana Maria Fiscina Sampaio ([email protected]) on 2016-07-25T15:57:03Z No. of bitstreams: 1 Panti-May JA A two year ecological....pdf: 316403 bytes, checksum: 4e80356daf5df2ea98e386b764daa8b9 (MD5)Approved for entry into archive by Ana Maria Fiscina Sampaio ([email protected]) on 2016-07-25T16:23:03Z (GMT) No. of bitstreams: 1 Panti-May JA A two year ecological....pdf: 316403 bytes, checksum: 4e80356daf5df2ea98e386b764daa8b9 (MD5)Made available in DSpace on 2016-07-25T16:23:03Z (GMT). No. of bitstreams: 1 Panti-May JA A two year ecological....pdf: 316403 bytes, checksum: 4e80356daf5df2ea98e386b764daa8b9 (MD5) Previous issue date: 2016Fundação Gonçalo Moniz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, BrasilFundação Gonçalo Moniz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, BrasilFundação Gonçalo Moniz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, BrasilFundação Gonçalo Moniz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, BrasilFundação Gonçalo Moniz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil / University of Liverpool. Institute of Integrative Biology. Liverpool, United KingdomFundação Gonçalo Moniz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, BrasilUniversity of Liverpool. Institute of Integrative Biology. Liverpool, United KingdomFundação Gonçalo Moniz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, BrasilFundação Gonçalo Moniz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, BrasilFundação Gonçalo Moniz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, BrasilMinistério da Saúde. Secretaria Municipal de Saúde. Centro de Controle de Zoonoses. Salvador, BA, BrasilFundação Gonçalo Moniz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil / Yale School of Public Health. Department of Epidemiology of Microbial Diseases. New Haven, Connecticut, USAFundação Gonçalo Moniz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil / Yale School of Public Health. Department of Epidemiology of Microbial Diseases. New Haven, Connecticut, USAYale School of Public Health. Department of Epidemiology of Microbial Diseases. New Haven, Connecticut, USAUniversity of Liverpool. Institute of Integrative Biology. Liverpool, United KingdomFundação Gonçalo Moniz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil / University of Liverpool. Institute of Integrative Biology. Liverpool, United Kingdom / Yale School of Public Health. Department of Epidemiology of Microbial Diseases. New Haven, Connecticut, USA / Universidade Federal da Bahia. Instituto de Saúde Coletiva. Salvador, BA, BrasilThe Norway or brown rat (Rattus norvegicus) is among the most ubiquitous of rodents. However, the lack of studies describing Norway rat populations from tropical areas have limited our understanding regarding their demography and seasonal dynamics. In this study, we describe seasonal pattern in the abundance, reproductive parameters, and morphometrics of Norway rat populations in Salvador, Brazil. Rodents were trapped over four seasonal trapping periods (2013-2014) from three valleys. A total of 802 Norway rats were trapped over the course of the study over 7653 trap-nights. Norway rat abundance was high, but there was no significant differences between seasons. The reproductive parameters (e.g. frequency of pregnant and lactating females) did not show statistical differences between seasons. Female rats collected in the rainy season were heavier and older than females from the dry season. Salvador rats had a high incidence of pregnancy and birth rate (estimated birth rate of 79 young per year) compared to previous studies. The information generated is critical for the understanding of the ecology of Norway rat, the main reservoir of Leptospira in Salvador. However, future studies examining the effect of rodent control programs aimed at reducing populations, and determining rates of recovery, will further clarify our understanding of population dynamics

Linking rattiness, geography and environmental degradation to spillover Leptospira infections in marginalised urban settings:an eco-epidemiological community-based cohort study in Brazil

Background:: Zoonotic spillover from animal reservoirs is responsible for a significant global public health burden, but the processes that promote spillover events are poorly understood in complex urban settings. Endemic transmission of Leptospira, the agent of leptospirosis, in marginalised urban communities occurs through human exposure to an environment contaminated by bacteria shed in the urine of the rat reservoir. However, it is unclear to what extent transmission is driven by variation in the distribution of rats or by the dispersal of bacteria in rainwater runoff and overflow from open sewer systems. Methods:: We conducted an eco-epidemiological study in a high-risk community in Salvador, Brazil, by prospectively following a cohort of 1401 residents to ascertain serological evidence for leptospiral infections. A concurrent rat ecology study was used to collect information on the fine-scale spatial distribution of ‘rattiness’, our proxy for rat abundance and exposure of interest. We developed and applied a novel geostatistical framework for joint spatial modelling of multiple indices of disease reservoir abundance and human infection risk. Results:: The estimated infection rate was 51.4 (95%CI 40.4, 64.2) infections per 1000 follow-up events. Infection risk increased with age until 30 years of age and was associated with male gender. Rattiness was positively associated with infection risk for residents across the entire study area, but this effect was stronger in higher elevation areas (OR 3.27 95% CI 1.68, 19.07) than in lower elevation areas (OR 1.14 95% CI 1.05, 1.53). Conclusions:: These findings suggest that, while frequent flooding events may disperse bacteria in regions of low elevation, environmental risk in higher elevation areas is more localised and directly driven by the distribution of local rat populations. The modelling framework developed may have broad applications in delineating complex animal-environment-human interactions during zoonotic spillover and identifying opportunities for public health intervention