Leptospira interrogans serovar Valbuzzi: a cause of severe pulmonary haemorrhages in the Andaman Islands

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Abstract
Outbreaks of leptospirosis that present with predominant pulmonary signs and symptoms have been occurring in the Andaman Islands since the late 1980s. Before this, pulmonary haemorrhage had not been observed as a common complication of leptospirosis in India. During an outbreak on North Andaman in 1997, four leptospire isolates were obtained from blood of a fatal case and three other patients who recovered. These isolates were characterized using serological and molecular techniques. Cross-agglutination absorption tests and microscopic agglutination tests using mAbs were used for serological characterization. Genetic typing was done using DNA sequencing of PCR products. Serologically, the isolates were closely related to strain Valbuzzi serovar Valbuzzi of serogroup Grippotyphosa. The sequences of PCR products from these isolates were compared with those of 45 strains belonging to seven species. The isolates showed 97.5–100 % sequence similarity to reference strains belonging to Leptospira interrogans, indicating that the isolates belong to L. interrogans. Serogroups Icterohaemorrhagiae and Australis have been incriminated as the cause of pulmonary haemorrhage in China, Korea and Australia. The four isolates characterized in the present study were obtained from patients with similar symptoms. However, they belonged to serovar Valbuzzi of serogroup Grippotyphosa, indicating that serogroups other than Icterohaemorrhagiae and Australis can also cause pulmonary haemorrhage.