A clone of Leptospira interroganssensu stricto is the major cause of leptospirosis in the archipelago of Andaman and Nicobar Islands, India

Abstract

Andaman and Nicobar Islands in India has a century long history of human leptospirosis. Several isolates have been recovered over the years from different locations. The present study was undertaken to understand the clonal relationship between all these pathogenic leptospires recovered from these islands. Arbitrarily primed polymerase chain reaction (AP-PCR) was employed to genetically characterize 40 isolates recovered during 1995--2001 and their fingerprints were compared with those of 26 reference strains of known genetic and serological affinities. Sequences of PCR-amplified products from representative isolates were compared with those of different strains belonging to seven genospecies. AP-PCR fingerprints revealed that 32 of the 40 isolates were clonal in nature and fingerprints of all the isolates matched with known reference strains of pathogenic Leptospira interrogans sensu stricto. Comparison of sequence data of PCR amplified products of reference strains and isolates also corroborated these findings. The study revealed that 80% of the isolates recovered from these islands were clonal in nature and all the isolates taken in the study belonged to Leptospira interrogans sensu stricto. An extension of the study in animal population would help in understanding the transmission dynamics of this commonly circulating clone in these islands, which in turn might help in effective control of this public health problem.