New aspects of leptospirosis in shrews and dogs; investigation on the prevalence and pathology

Leptospirosis is a complex and often underestimated global bacterial disease and continues to be of zoonotic concern. It is difficult to diagnose, has an unclear pathogenesis and several new Leptospira species of often unknown health impact have been discovered in recent years. Depending on the mammalian species affected and the causing serovar, the clinical disease can range from mild fever to severe internal bleeding, jaundice, and kidney failure. Other animals are asymptomatic carriers of Leptospira, maintaining the spirochaete in renal tissue and shedding it via the urine. In 2013 a new Leptospira species (L. tipperaryensis) was discovered in Ireland in greater white-toothed shrews (GWTS), an invasive species. This study investigates the prevalence and the impact of L. tipperaryensis on the health of the host (GWTS), and on the only Irish native shrew species, the pygmy shrew. A further study examines the association of a rarely reported renal pathology, exudative glomerulonephritis, in Swiss dogs and infection with Leptospira sp. These evolving new aspects of leptospirosis are evaluated by similar methods using histopathology, immunohistochemistry and PCR on renal tissues. Results showed a low prevalence of Leptospira sp. (0.4%) in Irish shrews in general, which was not linked to any significant renal pathology. Therefore, no negative impact of L. tipperaryensis on the health and distribution of the GWTS and the pygmy shrew was observed, and a further spread appears unlikely. Conversely, an association was found between this new fatal renal pathology of exudative glomerulonephritis and Leptospira sp. infection in dogs, suggesting an underlying different pathogenesis and possible new serovar. These studies have added significantly to the knowledge on leptospirosis. Future studies will be aimed in elucidating the pathogenesis of exudative glomerulonephritis and identifying the Leptospira species and serovar involved.