Abstract:
Understanding the processes driving parasite assemblages is particularly important in the context of zoonotic
infectious diseases. Leptospirosis is a widespread zoonotic bacterial infection caused by pathogenic species of the
genus Leptospira. Despite a wide range of animal hosts, information is still lacking on the factors shaping Leptospira
diversity in wild animal communities, especially in regions, such as tropical insular ecosystems, with high host species
richness and complex biogeographical patterns. Using a large dataset (34 mammal species) and a multilocus approach
at a regional scale, we analyzed the role of both host species diversity and geography in Leptospira genetic diversity in
terrestrial small mammals (rodents, tenrecs, and shrews) and bats from 10 different islands/countries in the western
Indian Ocean (WIO) and neighboring Africa. At least four Leptospira spp. (L. interrogans, L. borgpetersenii, L. kirschneri,
and L. mayottensis) and several yet-unidentified genetic clades contributed to a remarkable regional Leptospira
diversity, which was generally related to the local occurrence of the host species rather than the geography. In
addition, the genetic structure patterns varied between Leptospira spp., suggesting different evolutionary histories in
the region, which might reflect both in situ diversification of native mammals (for L. borgpetersenii) and the more
recent introduction of non-native host species (for L. interrogans). Our data also suggested that host shifts occurred
between bats and rodents, but further investigations are needed to determine how host ecology may influence these
events.
