Detection and Identification of Pathogenic Leptospira spp. Serogroups in Europe between 2017 and 2020 Applying a...

Leptospirosis is a neglected but reemerging worldwide zoonotic disease. Due to a rise in global temperature, precipitation, and urbanization, the risk of acquiring an infection with Leptospira (L.) spp. increases in Europe. One species affected by leptospirosis living close to the human is the dog. Even though dogs can shed low numbers of leptospires, their value as sentinel animal aiding in understanding environmental reservoirs might be even more important for human and animal health. Therefore, it is crucial to study the prevalence of pathogenic L. spp. in dogs and tailor coordinated protective measures like vaccination. This study aimed to screen a collection of purified DNA extracted from canine field samples (blood and urine, n = 239) collected in Europe from dogs suspected of leptospirosis and found positive by the lipL32 PCR used for diagnostics. A new simple and effective molecular approach was developed to identify different leptospiral serogroups using first a 16S rRNA PCR and 16S rRNA gene sequencing for genomospecies determination followed by a PCR targeting the rfb gene locus responsible for LPS biosynthesis for serogroup classification. In total, 172 DNA samples were successfully tested. Results show that L. Icterohaemorrhagiae was detected as the most prevalent serogroup in Europe (53%), followed by L. Australis serogroup (13%). At lower percentages, L. Pomona (5%), L. Autumnalis (4%), and L. Sejroe (2%) were identified. This work emphasizes that current L4 vaccines are relevant and should confer a high efficacy profile at least against L. Icterohaemorrhagiae and L. Australis serogroups.