Human leptospira isolates circulating in Mayotte (Indian Ocean) have unique serological and molecular features

Abstract

Leptospirosis is one of the most widespread zoonoses in the world. However, there is a lack of information on circulating Leptospira strains in remote parts of the world. We describe the serological and molecular features of leptospires isolated from 94 leptospirosis patients in Mayotte, a French department located in the Comoros archipelago, between 2007 and 2010. Multilocus sequence typing identified these isolates as Leptospira interrogans, L. kirschneri, L. borgpetersenii, and members of a previously undefined phylogenetic group. This group, consisting of 15 strains, could represent a novel species. Serological typing revealed that 70% of the isolates belonged to the serogroup complex Mini/Sejroe/Hebdomadis, followed by the serogroups Pyrogenes, Grippotyphosa, and Pomona. However, unambiguous typing at the serovar level was not possible for most of the strains because the isolate could belong to more than one serovar or because serovar and species did not match the original classification. Our results indicate that the serovar and genotype distribution in Mayotte differs from what is observed in other regions, thus suggesting a high degree of diversity of circulating isolates worldwide. These results are essential for the improvement of current diagnostic tools and provide a starting point for a better understanding of the epidemiology of leptospirosis in this area of endemicity.

Fig 1

Phylogenetic relationships of leptospirosis isolates (n = 95) based on MLST gene sequences. The tree was drawn using the UPGMA (unweighted pair group method with arithmetic average) algorithm based on average divergences of adk, lipL32, secY, rrs2, and lipL41. The species, ST, and presumptive serogroup are indicated. Circle sizes correspond to the numbers of strains for the ST. ST9 corresponds to an imported case from the Comoros islands.

Fig 2

Minimum spanning trees of Leptospira strains based on allelic profiles of adk, lipL32, rrs2, secY, and lipL41. (A) Minimum spanning tree of 372 Leptospira strains, including strains from Mayotte and previously described strains (22). (B) Minimum spanning tree of L. interrogans (n = 142), L. borgpetersenii (n = 109), and L. kirschneri (n = 51) showing the lack of overlap between strains from Mayotte and the MLST database published by Nalam et al. (22). Open circles correspond to genotypes previously described by Nalam et al. (22), while colored circles correspond to strains found in Mayotte. Bold, plain, and dashed lines linking the circles correspond to one, two, or more allelic mismatches, respectively; note that links with more than two allelic mismatches are not reliable.