Utility of Loop-mediated Isothermal Amplification Assay, Polymerase Chain Reaction, and ELISA for Diagnosis of Leptospirosis in South Indian Patients

BACKGROUND: Leptospirosis is a zoonotic disease which requires laboratory diagnosis for confirmation. MATERIALS AND METHODS: In this study serum samples from adults with acute undifferentiated fever (duration ≤15 days) were tested for IgM antibodies to Leptospira by ELISA, PCR for rrs gene and loop-mediated isothermal amplification (LAMP) assay for LipL32 and LipL41. RESULTS: Among the 150 sera tested, three were positive by PCR, LAMP and IgM ELISA/modified Faines’ criteria, two by only PCR; seven only by LAMP assay and forty fulfilled modified Faine's criteria (illness clinically compatible and IgM ELISA positive for leptospirosis). Clinical correlation revealed renal compromise, low platelet count and severe jaundice were significantly related to leptospirosis (P < 0.05). CONCLUSION: This study suggests that LAMP assay could be useful for diagnosis of leptospirosis during the 1(st) week of illness whereas IgM ELISA forms the mainstay of diagnosis from the 2(nd) week onward. Further studies especially community based, comparing ELISA, PCR, LAMP, culture and microscopic agglutination test are required to evaluate the veracity of these findings.