Molecular identification and associated risk factors of Hepatozoon canis among dogs visiting veterinary clinics in Tehran, Iran

Hepatozoon canis is a protozoan parasite with a complex life cycle, involving asexual development in vertebrate hosts and sexual reproduction within tick vectors. This study aimed to explore the prevalence and associated risk factors of H. canis in dogs admitted to veterinary clinics around in Tehran province, Iran. Blood samples were collected from dogs, including clinically asymptomatic and symptomatic individuals, and screened using PCR targeting the 18 S rRNA gene. Molecular analysis revealed 33 Hepatozoon-positive cases from 170 samples (19.4%; 95% CI: 13.5-25.4%), demonstrated significantly higher prevalence in rural and suburban environments, among female dogs aged 1-13 years. The most frequent clinical manifestations were also for lymphadenomegaly, fever, and muscular pain. While phylogenetic analysis demonstrated isolate clustering patterns consistent with established Hepatozoon species, alignment of partial 18 S rRNA gene sequences revealed both conserved domains and polymorphic sites, featuring nucleotide variations at 33 distinct positions. Our findings emphasize also the importance of molecular tools in diagnosing and characterizing infections caused by Hepatozoon, offering insights into the epidemiology and genetic diversity of this pathogen in canine populations around the world. These results also underscore the need for further studies on the ecology, transmission, and control strategies for H. canis in endemic regions.