New Insights on Leptospira Infections in a Canine Population from North Sardinia, Italy: A Sero-Epidemiological Study

SIMPLE SUMMARY: Leptospirosis is a widespread zoonosis caused by pathogenic spirochaetes of the genus Leptospira. Pathogenic leptospires live in the kidneys of different mammalian species and are excreted in the environment with the urine. The infection of humans is mainly caused by direct contact with infected animals or indirectly by contact with a contaminated environment. The aim of this study was to perform a sero-epidemiological survey to assess the presence of antibodies against Leptospira serovars in a representative sample of kennel and owned dogs from a selected area of Sardinia Island. In addition, kidney homogenates from rodents collected from the same study area were also analyzed by culture-based and real-time PCR-based testing methods. Higher antibody titers were observed against Leptospira Icterohaemmorrhagiae, which is believed to be responsible for the majority of severe cases of leptospirosis in humans. The detection of pathogenic Leptospira serotypes in dogs from northern Sardinia may represent a potential risk of infection for humans and contribute to the spread of the bacteria in the environment. Public health strategies to control possible Leptospira outbreaks should be implemented to prevent the disease from becoming a major medical and veterinary problem in this region. ABSTRACT: Leptospirosis is a widespread zoonosis recognized as a re-emerging infectious disease in a wide variety of animal species, including humans and dogs. No data exist regarding the presence of Leptospira species in the canine population of Sardinia Island. This study reports the first sero-survey for leptospirosis in kennel and owned dogs from six areas of the north of Sardinia. Sera from 1296 dogs were tested by microscopic agglutination test (MAT) specific for nine different serovars that are known to be well widespread in the Mediterranean environment. Moreover, kidney homogenates from rodents collected from the study area were also analyzed by LipL32 real-time PCR and multi-locus sequence type (MLST) on the basis of the analysis of seven concatenated loci. A total of 13% of the examined sera (95%CI: 11–15) tested positive for one or more serovars of Leptospira MAT detected; antibodies for serogroup Icterohaemorrhagiae (57%; 95%CI: 49–65) were the most common, followed by serovars Bratislava (22%; 95%CI: 16–28), Canicola (14%; 95%CI: 9–19), and Grippotyphosa (7%; 95%CI: 3–11). MLST analyses on isolates from rodents identified L. interrogans and L. borgpetersenii genomospecies. Different serovars belonging to pathogenic Leptospira serogroups are circulating in dogs from the island. Moreover, data obtained from rodents, indicated that rodents likely act as reservoir of spirochetes. Further sero-epidemiological studies are needed in order to obtain data from other collection sites in Sardinia and to increase the information on Leptospira species circulating in this area.