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PLoS Negl Trop Dis. 2017 Sep 15;11(9):e0005940. doi: 10.1371/journal.pntd.0005940. eCollection 2017 Sep.

Rapid, actionable diagnosis of urban epidemic leptospirosis using a pathogenic Leptospira lipL32-based real-time PCR assay.

Author information

1
Molecular Biology Section, Central Laboratory of the State of Paraná, Curitiba, Paraná Brazil.
2
National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
3
Gonçalo Moniz Institute, Oswaldo Cruz Foundation, Brazilian Ministry of Health, Salvador, Bahia, Brazil.
4
Institute of Collective Health, Federal University of the State of Bahia, Salvador, Bahia, Brazil.
5
Hospital das Clínicas, Federal University of the State of Paraná, Curitiba, Paraná, Brazil.
6
Department of Veterinary Medicine, Federal University of the State of Paraná, Curitiba, Paraná, Brazil.
7
Division of Infectious Diseases, Department of Medicine, University of California San Diego School of Medicine, La Jolla, California, United States of America.
8
Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, United States of America.

Abstract

BACKGROUND:

With a conservatively estimated 1 million cases of leptospirosis worldwide and a 5-10% fatality rate, the rapid diagnosis of leptospirosis leading to effective clinical and public health decision making is of high importance, and yet remains a challenge.

METHODOLOGY:

Based on parallel, population-based studies in two leptospirosis-endemic regions in Brazil, a real-time PCR assay which detects lipL32, a gene specifically present in pathogenic Leptospira, was assessed for the diagnostic effectiveness and accuracy. Patients identified by active hospital-based surveillance in Salvador and Curitiba during large urban leptospirosis epidemics were tested. Real-time PCR reactions were performed with DNA-extracted samples obtained from 127 confirmed and 23 unconfirmed cases suspected of leptospirosis, 122 patients with an acute febrile illness other than leptospirosis, and 60 healthy blood donors.

PRINCIPAL FINDINGS:

The PCR assay had a limit of detection of 280 Leptospira genomic equivalents/mL. Sensitivity for confirmed cases was 61% for whole blood and 29% for serum samples. Sensitivity was higher (86%) for samples collected within the first 6 days after onset of illness compared to those collected after 7 days (34%). The real-time PCR assay was able to detect leptospiral DNA in blood from 56% of serological non-confirmed cases. The overall specificity of the assay was 99%.

CONCLUSIONS:

These findings indicate that real-time PCR may be a reliable tool for early diagnosis of leptospirosis, which is decisive for clinical management of severe and life-threatening cases and for public health decision making.

PMID:
28915243
PMCID:
PMC5617227
DOI:
10.1371/journal.pntd.0005940
[Indexed for MEDLINE]
Free PMC Article

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