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PLoS Negl Trop Dis. 2018 Aug 31;12(8):e0006752. doi: 10.1371/journal.pntd.0006752. eCollection 2018 Aug.

Fine-scale GPS tracking to quantify human movement patterns and exposure to leptospires in the urban slum environment.

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Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, United States of America.
University of Kentucky College of Medicine, Lexington, Kentucky, United States of America.
Fulbright-Fogarty US Scholar Program, Fogarty International Center and the National Institute of Mental Health, Salvador, Brazil.
Vanderbilt-Emory-Cornell-Duke Global Health Consortium Fogarty Global Health Fellowship, Fogarty International Center and the National Institute of Mental Health, Nashville, Tennessee, United States of America.
Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Brazil.
Instituto de Saude Coletiva, Federal University of Bahia, Salvador, Brazil.
CHICAS, Lancaster Medical School, Lancaster University, Lancaster, United Kingdom.



Human movement is likely an important risk factor for environmentally-transmitted pathogens. While epidemiologic studies have traditionally focused on household risk factors, individual movement data could provide critical additional information about risk of exposure to such pathogens. We conducted global positioning system (GPS) tracking of urban slum residents to quantify their fine-scale movement patterns and evaluate their exposures to environmental sources of leptospirosis transmission.


We recruited participants from an ongoing cohort study in an urban slum in Brazil and tracked them for 24 hours at 30-second intervals. Among 172 subjects asked to participate in this cross-sectional study, 130 agreed to participate and 109 had good quality data and were included in analyses. The majority of recorded locations were near participant residences (87.7% within 50 meters of the house), regardless of age or gender. Similarly, exposure to environmental sources of leptospirosis transmission did not vary by age or gender. However, males, who have higher infection rates, visited a significantly larger area during the 24-hour period than did females (34,549m2 versus 22,733m2, p = 0.005). Four male participants had serologic evidence of Leptospira infection during the study period. These individuals had significantly larger activity spaces than uninfected males (61,310m2 vs 31,575m2, p = 0.006) and elevated exposure to rodent activity (p = 0.046) and trash deposits (p = 0.031).


GPS tracking was an effective tool for quantifying individual mobility in the complex urban slum environment and identifying risk exposures associated with that movement. This study suggests that in addition to source reduction, barrier interventions that reduce contact with transmission sources as slum residents move within their communities may be a useful prevention strategy for leptospirosis.

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