Molecular and genomic characterization of Leptospira isolates in humans and its relation to disease severity

The study was conducted with the aim to find out the genomo species and serovars of Leptospira by gene sequencing among blood samples tested positive for Leptospira PCR and to identify the species associated with highest mortality.

All samples with Ct value less than 35 were included in the study. After lipL32 PCR amplification and agarose gel electrophoresis, the amplified products were subjected to gene sequencing. Demographic details and mortality data were obtained from records.

66 out of the 70 samples showed maximum similarity to L.interrogans in sequencing. Other species identified include L.kirschneri and L. noguchi (5 samples). Among those tested positive, 14 patients died. L.interrogans was frequently isolated (13/14)from those who died. The different serovars identified include serovar canicola/hardjo/copenhageni, manilae/bataviaea/lai/icterohaemorrhagiae. Of these, serovars identified in death include Serovar canicola/hardjo/copenhageni/ranaram/manila.

Following sequencing, we identified the predominant species as L. interrogans (91 %) with case fatality rate of 19 %. They are found in animal population of our area, pointing the zoonotic potential of Leptospira. This highlights the need for sensitization of those with animal exposure regarding preventive strategies.