Outbreak of Leptospira borgpetersenii Serogroup Sejroe Infection in Kennel: The Role of Dogs as Sentinel in Specific Environments

Abstract

Kennels may represent high-risk environments for the diffusion of Leptospira infection in dogs and consequently a threat to public health. This study describes an outbreak of Leptospira infection in a kennel in Italy in 2020, both with clinically ill and asymptomatic dogs. Fifty-nine dogs, including three ill dogs, were tested for Leptospira spp. infection by the microscopic agglutination test (MAT) and real-time qPCR. Multi-locus sequence typing (MLST) analysis was used to genotype the identified leptospires. Thirty of the fifty-nine (50.9%) dogs had MAT titer and/or molecular positivity indicative of Leptospira infection. Twenty-two of the fifty-nine (37.3%) dogs exhibited seropositivity against at least one serovar belonging to the Sejroe serogroup, and MLST analysis identified L. borgpetersenii serogroup Sejroe (Leptospira ST155) as responsible for the outbreak. Up to now, Sejroe serogroup infection was sporadically reported in dogs. The extension of the MAT antigen panel to several serovars belonging to the serogroup Sejroe could be useful in the diagnosis of canine leptospirosis. Dogs may serve as sentinel of leptospires in specific environments, and surveillance of Leptospira infection in kennels is strongly recommended even when the correct vaccine prophylaxis is administered, because the vaccines currently available are not able to protect from all of the serogroups.

Keywords: Italy; Leptospira; Sejroe; dog; kennel; outbreak.

Figure 1

Phylogenetic tree built on concatenated sequences of the seven multi-locus sequence typing (MLST) loci (3111 bp) of the scheme proposed by Boonsilp and colleagues [17]. Phylogeny was conducted in MEGA 11 using the Neighbor-Joining method and bootstrap values are indicated on the respective branches. The samples are indicated with their ID, which represents a unique identification number of the relative reference strain present in the collection of the Italian Reference Centre for Animal Leptospirosis (IZSLER, Brescia, Italy).