Wild Boar (Sus scrofa) as Reservoir of Pathogenic and Intermediate Leptospira

Leptospirosis is a globally widespread zoonosis, with wildlife species playing a key role in the maintenance and environmental dissemination of Leptospira spp. Wild boar (Sus scrofa) are increasingly recognized as potential reservoir; however, molecular data on renal carriage of Leptospira spp. in Europe and particularly in Germany, remain scarce. In this study, 1281 wild boar kidney samples collected in the federal state of Saxony-Anhalt were analyzed by real-time PCR to investigate the presence of pathogenic and intermediate Leptospira DNA. Pathogenic Leptospira DNA was detected in 3.1% (95% CI = 2.3–4.2) of the samples, whereas intermediate Leptospira DNA was identified in 0.6% (95% CI = 0.3–1.2). Pathogenic Leptospira showed a widespread distribution across the study area, with a significantly higher prevalence in the district of Salzlandkreis (p = 0.04, OR = 3.4, CI = 0.8–10.3). Evaluation of host-related and environmental factors revealed a significant association between pathogenic Leptospira DNA detection and both sub-adult age class (χ2 = 13.1, df = 2, p = 0.0014) and autumn season (χ2 = 12.3, df = 3, p = 0.0066), whereas no significant association was observed for sex. Neither of these factors showed a significant relation with intermediate Leptospira spp. Sequence analyses of rrs and 16S rRNA genes predominantly identified as L. interrogans (62.5%), followed by L. borgpetersenii (20.0%) and L. kirschneri (5.0%). All intermediate Leptospira sequences were identified as L. fainei. Notably, this study provides the first molecular evidence of intermediate L. fainei DNA in wild boar kidneys in Germany. Overall, these findings suggest that wild boar may act as renal carriers of Leptospira spp. and support their potential relevance in the epidemiology of leptospirosis within wildlife populations in Saxony-Anhalt.