Leptospira spp. in Small Mammals from Areas with Low and High Human Hantavirus Incidences in South-West Germany

Introduction: Leptospirosis is caused by Leptospira spp. and is considered the most widespread zoonotic disease worldwide. It mimics nephropathia epidemica in humans, a disease mainly caused by Puumala hantavirus (PUUV). Small mammals are reservoirs for Leptospira spp. and PUUV. Seewis virus (SWSV) is a shrew-borne hantavirus with unknown pathogenicity. The objective of this study was to estimate the prevalence for Leptospira spp. and the frequency of Leptospira -hantavirus co-infections in small mammals collected at locations with high and low incidences in humans. Materials and Methods: In 2012 and 2013, 736 small mammals belonging to seven species ( Apodemus flavicollis , Microtus agrestis , Microtus arvalis , Myodes glareolus , Sorex araneus , S. coronatus , and S. minutus ) were collected at four high incidence sites (H1-H4) and four low (L1-L4) incidence sites for PUUV infection in humans. Kidney-derived DNA samples were tested for Leptospira spp. by real-time PCR targeting the lipl 32 gene and further analyzed by duplex PCR targeting the flaB and the secY genes. For the detection of Seewis virus, lung-derived DNA was tested via RT-PCR targeting the nucleocapsid gene. Results: Altogether, 42 of the 736 small mammals including 27 of 660 bank voles and 11 of 66 shrews, were positive for Leptospira spp., while Sorex spp. (14.7%) showed significantly higher prevalences compared to bank voles (4.1%). Detected Leptospira spp. were pathogenic species other than L. kirschneri . Significantly more Leptospira -positive bank voles were found at H sites than at L sites. Altogether 22.2% of positive bank voles were infected with PUUV. Double infection of PUUV and Leptospira spp. occurrence in bank voles is 1.86 times (OR = 1.86; 95% CI: 0.72–4.73) more likely than infections with each pathogen separately. Discussion: Leptospira - positive bank voles are focally positively associated with PUUV infection in bank voles and with human hantavirus cases. It should be considered that shrews may serve as Leptospira spp. reservoirs.