Screening of patients with acute febrile illness for leptospirosis using clinical criteria and serology.

ABSTRACT

BACKGROUND: Leptospirosis is one of the common zoonoses but, in most instances, the infection goes unnoticed. Rapid diagnostic modalities are needed to diagnose the disease in the early stages. We assessed the usefulness of clinical criteria and compared these with enzyme-linked immunosorbentassay (ELISA) for the early detection of leptospirosis. METHODS: One hundred patients with a febrile illness for > 7 days were screened by Faine criteria and their sera were subjected to both IgM and IgG ELISA using a commercially available kit (Institut Virion Serion GmbH, Warburg, Germany). RESULTS: Twenty-six patients satisfied the clinical criteria for leptospirosis and 8 of them tested positive for IgM antibodies while 1 patient who was clinically negative tested positive by serology. Thus, Faine criteria had a sensitivity of 88.9%, specificity of 80.2%, positive predictive value of 30.8% and a negative predictive value of 98.6%. Paired serum samples were obtained from 70 patients but the IgG levels of only 2 showed a 4-fold rise. CONCLUSION: Faine criteria has moderate sensitivity and specificity but a high negative predictive value in comparison with IgM ELISA. The high negative predictive value may help to screen patients with acute febrile illness for leptospirosis during the early phase of the disease.