Prevalence and Genomic Characterization of Brucella canis Strains Isolated from Kennels, Household, and Stray Dogs in Chile

SIMPLE SUMMARY: Canine brucellosis caused by Brucella canis is a zoonotic disease that is considered the main infectious cause of infertility and reproductive failure in dogs worldwide, particularly in Latin America. Reports of B. canis infection in people have increased, especially in people who work with dogs and their owners, where the adoption of stray dogs poses a public health risk. Thus, this study determined the prevalence of infection in kennels, household, and stray dogs in the Metropolitan region, Chile, recording the genomic characteristics of the isolated circulating strains. Our results demonstrate that the infection is widespread in the three canine populations analyzed, with no differences in age or sex, and most of the infected animals do not show clinical signs or bacteremia. Furthermore, the high genetic similarity of the isolated strains suggests a common transmission route throughout the country. This study corroborates the need to implement official strategies for the control and prevention of B. canis infection, including sanitary, diagnostic, and educational measures under the One Health vision. ABSTRACT: Canine brucellosis caused by Brucella canis is a zoonotic disease that causes reproductive alterations in dogs, such as infertility, abortion, and epididymitis. This pathogen is especially prevalent in South America, and due to the lack of official control programs and the growing trend of adopting dogs it constitutes a public health risk that must be addressed. The aim of this study was to determine the prevalence of B. canis infection in kennel, shelter, and household dogs and to characterize the genomic properties of circulating strains, including ure and virB operons and omp25/31 genes. Samples from 771 dogs were obtained, and the infection was detected by blood culture and/or serology in 7.0% of the animals. The complete ure and virB operons and the omp25/31 genes were detected. Interestingly, we found different single-nucleotide polymorphisms (SNPs) in some of the analyzed genes, which could mean a change in the fitness or virulence of these strains. This study provides further evidence about dogs as a source of B. canis strains that can infect people. This also highlights the need to implement official control programs, including the mandatory testing of dogs, especially stray dogs, before adoption.