Antigenic and genetic relatedness of Leptospira strains isolated from the Andaman Islands in 1929 and 2001.

Leptospirosis is a major public health problem in Andaman Islands. Several strains of Leptospira have been isolated from the Andamans over the years. Leptospires isolated recently from human cases were compared with one of the earliest available isolates from these islands, dating back to 1929, to study their serological and genetic relatedness. Randomly amplified polymorphic DNA (RAPD) fingerprints of the isolates, generated with a primer used previously to differentiate between Leptospira species and serovars, revealed that some of the recent isolates were genetically identical to the 1929 isolate. The antigenic properties of these strains, as revealed by microscopic agglutination tests with group-specific rabbit antisera and mAbs, were also similar. These findings suggest that a Leptospira strain originally isolated in 1929 has possibly persisted in these islands for over 70 years and continues to cause acute leptospirosis in humans.