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PLoS Negl Trop Dis. 2015 Jun 5;9(6):e0003819. doi: 10.1371/journal.pntd.0003819. eCollection 2015.

Patterns in Leptospira Shedding in Norway Rats (Rattus norvegicus) from Brazilian Slum Communities at High Risk of Disease Transmission.

Author information

1
Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Brazil; Instituto de Saúde Coletiva, Universidade Federal da Bahia (UFBA), Salvador, Brazil; Department of Epidemiology of Microbial Disease, Yale School of Public Health, New Haven, Connecticut, United States of America; Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom.
2
Department of Epidemiology of Microbial Disease, Yale School of Public Health, New Haven, Connecticut, United States of America.
3
Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Brazil.
4
Centro de Controle de Zoonoses, Secretaria Municipal de Saúde, Ministério da Saúde, Salvador, Brazil.
5
Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Ministério da Saúde, Salvador, Brazil; Department of Epidemiology of Microbial Disease, Yale School of Public Health, New Haven, Connecticut, United States of America.
6
Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom.

Abstract

BACKGROUND:

We address some critical but unknown parameters of individuals and populations of Norway rats (Rattus norvegicus) that influence leptospiral infection, maintenance and spirochetal loads shed in urine, which contaminates the environment ultimately leading to human infection.

METHODOLOGY/PRINCIPAL FINDINGS:

Our study, conducted in Salvador, Brazil, established the average load of leptospires in positive kidneys to be 5.9 x 10(6) per mL (range 3.1-8.2 x10(6)) genome equivalents (GEq), similar to the 6.1 x 10(6) per ml (range 2.2-9.4 x10(6)) average obtained from paired urines, with a significant positive correlation (R2=0.78) between the two. Based on bivariate and multivariate modeling, we found with both kidney and urine samples that leptospiral loads increased with the age of rats (based on the index of body length to mass), MAT titer and the presence of wounding/scars, and varied with site of capture. Some associations were modified by sex but trends were apparent. Combining with data on the demographic properties and prevalence of leptospiral carriage in rat populations in Salvador, we estimated that daily leptospiral loads shed in the urine of a population of 82 individuals exceeded 9.1 x 10(10) leptospires.

CONCLUSIONS/SIGNIFICANCE:

These factors directly influence the risk of leptospiral acquisition among humans and provide essential epidemiological information linking properties of rat populations with risk of human infection.

PMID:
26047009
PMCID:
PMC4457861
DOI:
10.1371/journal.pntd.0003819
[Indexed for MEDLINE]
Free PMC Article

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