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Open Access Research article

Detection of human leptospirosis as a cause of acute fever by capture ELISA using a Leptospira interrogans serovar Copenhageni (M20) derived antigen

Enrique Canal1, Simon Pollett12*, Kristen Heitzinger1, Michael Gregory1, Matthew Kasper1, Eric Halsey1, Yocelinda Meza1, Kalina Campos3, Juan Perez1, Rina Meza1, Maruja Bernal1, Alfredo Guillen4, Tadeusz J Kochel15, Benjamin Espinosa15, Eric R Hall15 and Ryan C Maves16

Author Affiliations

1 U.S. Naval Medical Research Unit No. 6, Lima, Peru

2 Sydney Institute of Emerging Infections and Biosecurity, University of Sydney, Sydney, Australia

3 Institute of Tropical Medicine ‘Alexander von Humboldt’, Universidad Peruana Cayetano Heredia, Lima, Peru

4 Universidad Nacional Federico Villarreal, Lima, Peru

5 Naval Medical Research Center, Silver Spring, MD, USA

6 Division of Infectious Diseases, Naval Medical Center, San Diego, CA, USA

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BMC Infectious Diseases 2013, 13:438  doi:10.1186/1471-2334-13-438

Published: 20 September 2013

Abstract

Background

Leptospirosis is a potentially lethal zoonosis mainly affecting low-resource tropical countries, including Peru and its neighbouring countries. Timely diagnosis of leptospirosis is critical but may be challenging in the regions where it is most prevalent. The serodiagnostic gold standard microagglutination test (MAT) may be technically prohibitive. Our objective in this study was to assess the sensitivity, specificity, and predictive value of an IgM antibody capture enzyme-linked immunoassay (MAC-ELISA) derived from the M20 strain of Leptospira interrogans serovar Copenhageni (M20) by comparison to MAT, which was used as the gold standard method of diagnosis.

Methods

Acute and convalescent sera from participants participating in a passive febrile surveillance study in multiple regions of Peru were tested by both IgM MAC-ELISA and MAT. The sensitivity, specificity, positive and negative predictive value (PPV, NPV) of the MAC-ELISA assay for acute, convalescent and paired sera by comparison to MAT were calculated.

Results

The sensitivity, specificity, PPV and NPV of the MAC-ELISA assay for acute sera were 92.3%, 56.0%, 35.3% and 96.6% respectively. For convalescent sera, the sensitivity, specificity, PPV and NPV of the MAC-ELISA assay were 93.3%, 51.5%, 63.6% and 89.5% respectively. For paired sera, the sensitivity, specificity, PPV and NPV of the MAC-ELISA assay were 93.6%, 37.5%, 59.2%, 85.7% respectively.

Conclusions

The M20 MAC-ELISA assay performed with a high sensitivity and low specificity in the acute phase of illness. Sensitivity was similar as compared with MAT in the convalescent phase and specificity remained low. Paired sera were the most sensitive but least specific by comparison to MAT serodiagnosis. NPV for acute, convalescent and paired sera was high. The limited specificity and high sensitivity of the MAC-ELISA IgM suggests that it would be most valuable to exclude leptospirosis in low-resource regions that lack immediate access to definitive reference laboratory techniques such as MAT.

Keywords:
Leptospirosis; IgM; MAC ELISA; MAT; Peru