Serological & molecular approaches for diagnosis of leptospirosis in a tertiary care hospital in north India: A 10-year study.

Background & objectives: Leptospirosis, a spirochetal zoonosis, is underreported from the northern States of India. This study reports results of a 10-year retrospective sero-epidemiological survey of leptospirosis conducted in a tertiary care hospital in New Delhi, India. Method: A total of 1453 patients clinically suspected for leptospirosis were included and investigated initially by IgM ELISA. A proportion of these were subjected to culture, microscopic agglutination test (MAT) and polymerase chain reaction (PCR). Results: Of the 1453 patients, 391 (26.90%) were positive serologically by IgM ELISA. Seropositive and seronegative patients revealed no significant difference in clinical features and laboratory parameters. Amongst the IgM seropositive cases, culture for leptospires was positive in 5 of 192 (2.6%), MAT in 50 of 138 (36.23%), PCR from blood and urine in 10 of 115 (8.7%) and 10 of 38 (26.31%) cases, respectively. In Leptospira spp. positive patients co-infections with viral hepatitis E, malaria and dengue fever were diagnosed in 27 cases. Interpretation & conclusions: The overall seropositivity for leptospirosis was 26.9 per cent in our study. A decreasing trend in seropositivity was observed in recent years. Co-infections with malaria, dengue, hepatitis A and E were also seen. Since leptospirosis is a treatable disease, correct and rapid diagnosis may help in effective management of patients.

Characterization of trypsin extractable antigens of Leptospira interrogans serovars pomona, bataviae & L. biflexa serovar patoc.

Leptospira strains after treatment with trypsin released an antigen (Tx) which consisted of protein (4.2 mg/ml), carbohydrate (0.39 mg/ml) and hexosamine (0.025 mg/ml). Immunodiffusion, immunoelectrophoresis and indirect haemagglutination tests revealed serological cross reactions among the three strains used. Inhibition of microscopic agglutination reaction by the Tx antigen was observed in homologous system only. The antigen was partially sensitive to heat (80 degrees C for 10 min) as detected by immunodiffusion and microscopic agglutination inhibition. These data revealed the presence of serovar-specific and genus-specific antigens on Leptospira strains. It is suggested that this antigen could be useful in developing a serodiagnostic test for leptospirosis.