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Soni N, Eyre MT, Souza FN, Diggle PJ, Ko AI, Begon M, Pickup R, Childs JE, Khalil H, Carvalho-Pereira TSA, Pertile AC, Carvalho M, de Oliveira D, Nery N, Giorgi E, Costa F. Disentangling the influence of reservoir abundance and pathogen shedding on zoonotic spillover of the Leptospira agent in urban informal settlements. Front Public Health 2024; 12:1447592. [PMID: 39360250 PMCID: PMC11445007 DOI: 10.3389/fpubh.2024.1447592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2024] [Accepted: 08/28/2024] [Indexed: 10/04/2024] Open
Abstract
Rats are major reservoirs for pathogenic Leptospira, the bacteria causing leptospirosis, particularly in urban informal settlements. However, the impact of variation in rat abundance and pathogen shedding rates on spillover transmission to humans remains unclear. This study aimed to investigate how spatial variation in reservoir abundance and pathogen pressure affect Leptospira spillover transmission to humans in a Brazilian urban informal settlement. A longitudinal eco-epidemiological study was conducted from 2013 to 2014 to characterize the spatial distribution of rat abundance and Leptospira shedding rates in rats and determine the association with human infection risk in a cohort of 2,206 community residents. Tracking plates and live-trapping were used to measure rat abundance and quantify rat shedding status and load. In parallel, four sequential biannual serosurveys were used to identify human Leptospira infections. To evaluate the role of shedding on human risk, we built three statistical models for: (1) the relative abundance of rats, (2) the shedding rate by individual rats, and (3) human Leptospira infection, in which "total shedding", obtained by multiplying the predictions from those two models, was used as a risk factor. We found that Leptospira shedding was associated with older and sexually mature rats and varied spatially and temporally-higher at valley bottoms and with seasonal rainfall (December to March). The point estimate for "total shedding" by rat populations was positive, i.e., Leptospira infection risk increased with total shedding, but the association was not significant [odds ratio (OR) = 1.1; 95% confidence interval (CI): 0.9, 1.4]. This positive trend was mainly driven by rat abundance, rather than individual rat shedding (OR = 1.8; 95% CI: 0.6, 5.4 vs. OR = 1.0; 95% CI: 0.7, 1.4]. Infection risk was higher in areas with more vegetative land cover (OR = 2.4; 95% CI: 1.2, 4.8), and when floodwater entered the house (OR = 2.4; 95% CI: 1.6, 3.4). Our findings indicate that environmental and hydrological factors play a more significant role in Leptospira spillover than rat associated factors. Furthermore, we developed a novel approach combining several models to elucidate complex links between animal reservoir abundance, pathogen shedding and environmental factors on zoonotic spillover in humans that can be extended to other environmentally transmitted diseases.
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Affiliation(s)
- Nirali Soni
- Centre for Health Informatics, Computing, and Statistics, Lancaster University Medical School, Lancaster, United Kingdom
| | - Max T Eyre
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Fábio N Souza
- Institute of Collective Health, Federal University of Bahia, Salvador, Bahia, Brazil
- Instituto Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Bahia, Brazil
| | - Peter J Diggle
- Centre for Health Informatics, Computing, and Statistics, Lancaster University Medical School, Lancaster, United Kingdom
| | - Albert I Ko
- Instituto Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Bahia, Brazil
- Department of Epidemiology of Microbial Diseases, School of Public Health, Yale University, New Haven, CT, United States
| | - Mike Begon
- Department of Evolution, Ecology and Behaviour, University of Liverpool, Liverpool, United Kingdom
| | - Roger Pickup
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, United Kingdom
| | - James E Childs
- Department of Epidemiology of Microbial Diseases, School of Public Health, Yale University, New Haven, CT, United States
| | - Hussein Khalil
- Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences, Umeå, Sweden
| | | | - Arsinoê C Pertile
- Instituto Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Bahia, Brazil
| | - Mayara Carvalho
- Instituto Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Bahia, Brazil
| | - Daiana de Oliveira
- Institute of Collective Health, Federal University of Bahia, Salvador, Bahia, Brazil
- Instituto Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Bahia, Brazil
| | - Nivison Nery
- Instituto Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Bahia, Brazil
- Department of Epidemiology of Microbial Diseases, School of Public Health, Yale University, New Haven, CT, United States
| | - Emanuele Giorgi
- Centre for Health Informatics, Computing, and Statistics, Lancaster University Medical School, Lancaster, United Kingdom
| | - Federico Costa
- Institute of Collective Health, Federal University of Bahia, Salvador, Bahia, Brazil
- Instituto Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Bahia, Brazil
- Department of Epidemiology of Microbial Diseases, School of Public Health, Yale University, New Haven, CT, United States
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Bradley EA, Lockaby G. Leptospirosis and the Environment: A Review and Future Directions. Pathogens 2023; 12:1167. [PMID: 37764975 PMCID: PMC10538202 DOI: 10.3390/pathogens12091167] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 08/31/2023] [Accepted: 09/13/2023] [Indexed: 09/29/2023] Open
Abstract
Leptospirosis is a zoonotic disease of global importance with significant morbidity and mortality. However, the disease is frequently overlooked and underdiagnosed, leading to uncertainty of the true scale and severity of the disease. A neglected tropical disease, leptospirosis disproportionately impacts disadvantaged socioeconomic communities most vulnerable to outbreaks of zoonotic disease, due to contact with infectious animals and contaminated soils and waters. With growing evidence that Leptospira survives, persists, and reproduces in the environment, this paper reviews the current understanding of the pathogen in the environment and highlights the unknowns that are most important for future study. Through a systematic Boolean review of the literature, our study finds that detailed field-based study of Leptospira prevalence, survival, and transmission in natural waters and soils is lacking from the current literature. This review identified a strong need for assessment of physical characteristics and biogeochemical processes that support long-term viability of Leptospira in the environment followed by epidemiological assessment of the transmission and movement of the same strains of Leptospira in the present wildlife and livestock as the first steps in improving our understanding of the environmental stage of the leptospirosis transmission cycle.
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Affiliation(s)
- Elizabeth A. Bradley
- College of Forestry, Wildlife, and Environment, Auburn University, Auburn, AL 36849, USA
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Cunha M, Costa F, Ribeiro GS, Carvalho MS, Reis RB, Nery Jr N, Pischel L, Gouveia EL, Santos AC, Queiroz A, Wunder Jr. EA, Reis MG, Diggle PJ, Ko AI. Rainfall and other meteorological factors as drivers of urban transmission of leptospirosis. PLoS Negl Trop Dis 2022; 16:e0007507. [PMID: 35404948 PMCID: PMC9022820 DOI: 10.1371/journal.pntd.0007507] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 04/21/2022] [Accepted: 03/17/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Leptospirosis is an important public health problem affecting vulnerable urban slum populations in developing country settings. However, the complex interaction of meteorological factors driving the temporal trends of leptospirosis remain incompletely understood. METHODS AND FINDINGS From March 1996-March 2010, we investigated the association between the weekly incidence of leptospirosis and meteorological anomalies in the city of Salvador, Brazil by using a dynamic generalized linear model that accounted for time lags, overall trend, and seasonal variation. Our model showed an increase of leptospirosis cases associated with higher than expected rainfall, lower than expected temperature and higher than expected humidity. There was a lag of one-to-two weeks between weekly values for significant meteorological variables and leptospirosis incidence. Independent of the season, a weekly cumulative rainfall anomaly of 20 mm increased the risk of leptospirosis by 12% compared to a week following the expected seasonal pattern. Finally, over the 14-year study period, the annual incidence of leptospirosis decreased significantly by a factor of 2.7 (8.3 versus 3.0 per 100,000 people), independently of variations in climate. CONCLUSIONS Strategies to control leptospirosis should focus on avoiding contact with contaminated sources of Leptospira as well as on increasing awareness in the population and health professionals within the short time window after low-level or extreme high-level rainfall events. Increased leptospirosis incidence was restricted to one-to-two weeks after those events suggesting that infectious Leptospira survival may be limited to short time intervals.
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Affiliation(s)
- Marcelo Cunha
- Escola Nacional de Saúde Pública, Fundação Oswaldo Cruz, Ministério da Saúde, Rio de Janeiro, Brazil
| | - Federico Costa
- Instituto de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Brazil
- Instituto de Saúde Coletiva, Universidade Federal da Bahia, Salvador, Brazil
- Faculty of Health and Medicine, University of Lancaster, Lancaster, United Kingdom
- Department of Epidemiology of Microbial Diseases, School of Public Health, Yale University, New Heaven, Connecticut, United States of America
| | - Guilherme S. Ribeiro
- Instituto de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Brazil
- Faculdade de Medicina, Universidade Federal da Bahia, Salvador, Brazil
| | - Marilia S. Carvalho
- Escola Nacional de Saúde Pública, Fundação Oswaldo Cruz, Ministério da Saúde, Rio de Janeiro, Brazil
| | - Renato B. Reis
- Instituto de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Brazil
| | - Nivison Nery Jr
- Instituto de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Brazil
- Instituto de Saúde Coletiva, Universidade Federal da Bahia, Salvador, Brazil
| | - Lauren Pischel
- Department of Epidemiology of Microbial Diseases, School of Public Health, Yale University, New Heaven, Connecticut, United States of America
| | - Edilane L. Gouveia
- Instituto de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Brazil
| | - Andreia C. Santos
- Instituto de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Brazil
| | - Adriano Queiroz
- Instituto de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Brazil
| | - Elsio A. Wunder Jr.
- Instituto de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Brazil
- Department of Epidemiology of Microbial Diseases, School of Public Health, Yale University, New Heaven, Connecticut, United States of America
| | - Mitermayer G. Reis
- Instituto de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Brazil
- Department of Epidemiology of Microbial Diseases, School of Public Health, Yale University, New Heaven, Connecticut, United States of America
- Faculdade de Medicina, Universidade Federal da Bahia, Salvador, Brazil
| | - Peter J Diggle
- Faculty of Health and Medicine, University of Lancaster, Lancaster, United Kingdom
- Department of Epidemiology of Microbial Diseases, School of Public Health, Yale University, New Heaven, Connecticut, United States of America
| | - Albert I. Ko
- Instituto de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Brazil
- Department of Epidemiology of Microbial Diseases, School of Public Health, Yale University, New Heaven, Connecticut, United States of America
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Assessment of Epidemiological Implications Due to Serial Tropical Cyclones in India: Introspecting the Recent Sanitation Interventions. Disaster Med Public Health Prep 2020; 15:181-190. [PMID: 31928562 DOI: 10.1017/dmp.2019.129] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVES The Indian subcontinent is prone to tropical cyclones that used to originate in the North Indian Ocean. Through this study, an inventory of disease outbreaks for the tropical cyclone-affected regions from 2010 to 2018 has been compiled. This inventory is used to assess the success of recent sanitation intervention, Swachh Bharat Mission, also known as the Clean India Mission. METHODS Meteorological parameters from the Indian satellites were used to demarcate the cyclone-affected area. Disease outbreaks and epidemics during the tropical cyclones were compiled from the Integrated Disease Surveillance Program and other relevant sources. The inventory has been used to track the effect of recent sanitation interventions on disease outbreaks. RESULTS Districts in the eastern coast of India are frequently affected due to tropical cyclones that have originated from the North Indian Ocean. Infectious diseases like the acute diarrheal diseases, vector-borne diseases, viral fevers, enteric fevers, and food poisoning have recursively occurred during the cyclonic events and persisted up to 2 weeks from the cyclonic episode. The effectiveness of the Clean India Mission is evident during the recent cyclones, Ockhi, Titli, and Gaja, where a significantly lower number of infectious disease outbreaks were recorded. CONCLUSIONS The Clean India Mission has exhibited positive results on the public health consequences associated with tropical cyclones.
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