Surveillance for Leptospira sp. in Native and Invasive Shrews in Ireland Compared with Cohabitating Shrews in France

Leptospirosis is a complex and often underestimated global bacterial disease that continues to be of zoonotic concern. It is difficult to diagnose and has an unclear pathogenesis. Several new species of the genus Leptospira have been discovered in recent years; the impact of these species on animal health is unknown. In 2013, Leptospira tipperaryensis was first identified in greater white-toothed shrews (GWTSs, Crocidura russula) in Ireland, where they are an invasive species that displaces the native pygmy shrew (Sorex minutus). This study investigated the prevalence of Leptospira spp., including L. tipperaryensis, and their potential impact on the health of shrews from Ireland using histopathology (n=212), immunohistochemistry (IHC; n=206), and quantitative PCR (n=168) on renal tissues. Shrews (n=81) from Belle Île, France were examined as a species and habitat control group using histopathology (n=81) and IHC (n=79). No Leptospira were detected with any of the methods in renal tissues from shrews sampled in Ireland and there was no significant renal pathology. In contrast, 34.6% (28/81) of shrews from Belle Île were positive on IHC for Leptospira sp. and had associated chronic nephritis in histopathology. The results do not indicate a negative impact by L. tipperaryensis or other Leptospira spp. on the health and distribution of the GWTS and the pygmy shrew in Ireland; onward transmission within the shrew population currently appears unlikely.