Background: Leptospirosis is a worldwide public health problem. Early diagnosis of leptospirosis is essential since antibiotic therapy is useful only when it is initiated early in the course of illness. The purpose of this study was to evaluate dark field microscopy for early diagnosis of leptospirosis.

Materials and Methods: A total of 81 blood samples were collected from the suspected patients. Blood samples (5ml each) were collected aseptically in two sterile SV10 vials, one containing 500 µl 1% sodium oxalate solution P^H 8.0 and another in dry tube. The former sample was used for dark field microscopy and the other was used for serodiagnosis by MAT and ELISA. Blood was also collected from 50 healthy blood donors and tested by DFM, ELISA and MAT.

Results: It was found that found that DFM sensitivity is 55.55% (45/81), IgM ELISA is 65.43% (53/81) and MAT is 54.32% (44 /81). On evaluation of DFM we found, its sensitivity is 61.64% (45/73), specificity is 95.23% (40/42), positive predictive value is 95.74% (45/47) and negative predictive value is 58.82% (40/68).

Conclusion: Sensitivity of DFM was found to be lesser than that of ELISA but slightly more than that of MAT. Evaluation of DFM showed good sensitivity and greater specificity. Hence DFM can be performed using a good dark field microscope and anticoagulant added blood for the early diagnosis of leptospirosis along with ELISA.

Keywords:  DFM, Leptospira, ELISA, MAT, Spirochaete.

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Binay Kumar Singh

Department of Microbiology, Patliputra Medical College, Dhanbad, India