Brucella canis as an Underrecognized Zoonotic Threat: Human Infection, Diagnostic Challenges, and Public Health Implications.

Brucella canis is a recognized zoonotic pathogen associated with human infection in a variety of epidemiological settings; however, the magnitude of its impact on human health remains uncertain because of its nonspecific clinical presentation, limited availability of species-specific diagnostic methods, and insufficient awareness among physicians, veterinarians, microbiologists, and public health professionals. Unlike classical human brucellosis caused by smooth Brucella species, B. canis infection may be overlooked, potentially leading to delayed diagnosis and incomplete case detection. This narrative review summarizes current evidence on the epidemiology, transmission pathways, occupational and non-occupational risk factors, clinical manifestations, diagnostic approaches, treatment, and public health implications of human B. canis infection. Particular emphasis is placed on published human cases, laboratory-acquired infections, household clusters, cases reported in different age and immune-status groups, and the biological and epidemiological characteristics of canine infection that facilitate zoonotic transmission. The review further examines the limitations of currently available microbiological, serological, and molecular diagnostic methods, the lack of harmonized surveillance systems, and the consequences of inadequate recognition from a One Health perspective. Collectively, the available evidence confirms the zoonotic potential of B. canis but remains insufficient to define the true burden of human infection. Improving clinical awareness, strengthening collaboration between veterinary and human health sectors, expanding access to standardized diagnostic tools, and implementing integrated One Health surveillance may improve recognition and reduce zoonotic risk.