• hunting activity
• pathogens transmission
• wildlife
• Sus scrofa
• zoonosis
• Leptospirosis
• wild boar
• epidemiology
• Leptospira

Leptospirosis is a neglected and re-emerging zoonoses. A significant proportion of human cases are strictly associated to the contact with domestic and wild animals, which act as maintenance-hosts (reservoirs). Indeed, human is considered as incidental host that could be infected after the direct or indirect contact with contaminated urine, shed by reservoirs. Among reservoirs, wild boar (Sus scrofa), as well as all swine, are considered the well-known maintenance-host to Pomona, Tarassovi and Australis Leptospira serogroups. Moreover, due to their population abundance in all European countries, this animal species could be a suitable indicator of Leptospira prevalence into a specific area. Therefore, in this PhD project, the Leptospira prevalence in free ranging wild boar was investigated. Through bacteriological, serological, and molecular assays, the prevalence of leptospirosis in kidneys of wild boar specimens collected in Tuscany and Liguria regions resulted between 8% and 15%. Within sera, to the Microscopic Agglutination Test (MAT), Australis was the most represented serogroup, followed by Pomona, and Tarassovi. Moreover, Leptospira cultures were positive and were identified through Multi-Locus Sequence Type (MLST) as L. borgpetersenii serovar Tarassovi, and L. interrogans serovar Bratislava. The pathogenic Leptospira DNAs were detected using Real-Time PCR in wild boar kidney, that, after the amplification of rrs2 gene, highlighted their belonging to genomospecies L. interrogans, L. borgpetersenii, and L. kirschneri. Moreover, intermediate Leptospira, all belonging to L. fainei. This identification opens a new scenario on leptospirosis epidemiology, especially for the renal colonization in wildlife. Also, the presence of Leptospira in reproductive system tissue samples (testicles, epididymides, uteri) as well as placentas and foetuses were assessed in the same sampled specimens. Pathogens were isolated from the testicles and epididymides, identifying them, by MLST, as Leptospira interrogans serogroup Australis and Leptospira kirschneri serogroup Grippotyphosa. Moreover, using Real-Time PCR and rrs2 sequence, positivity was reported in uteri, placenta, and foetuses, as well as in testicles and epididymides, associable to L. interrogans and L. kirschneri genomospecies. As for kidney Leptospira fainei DNA was found in testicles and epididymides. Finally, two investigations were performed on Leptospira reference strains to investigate the antimicrobial tigecycline and salt resistances. The Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined through the microdilution method. Bratislava and Tarassovi strains showed the highest resistance to tigecycline. Considering salt, Tarassovi was the most resistant, while, interesting trends were reported for Pomona and Bratislava, highlighting low MIC values but high MBC values.
To conclude, this PhD project provides to give new information about the spread and persistence of Leptospira strains in wild boar, suggesting the transmission and the sharing between wild and domestic animals. Also, the transmission from wild boar to hunting dogs represent an important risk for human health, especially for intermediate Leptospira strains, more underestimated and until today poorly known.