Estimated prevalence and genetic diversity of Bartonella species in small mammals in Europe: Systematic review and meta-analysis

Bartonellosis is a neglected vector-borne zoonotic disease caused by Bartonella species that infect a wide array of mammals. The adaptation of Bartonella to various animal hosts, including small mammal populations, has been reported, indicating their potential as a significant reservoir harboring a high genetic diversity of these pathogens, thereby posing a risk for zoonotic transmission to humans through close ecological or physical contact. Thus, this study aimed to give an overview of the prevalence and the genetic diversity of Bartonella spp in small mammals throughout Europe. Consequently, a systematic review was undertaken by retrieving all relevant articles indexed in PubMed, Scopus and Web of Science. Subsequently, a meta-analysis was performed to compute the pooled prevalence of Bartonella spp. Moreover, subgroup moderator analyses were then performed, examining the impact of sub-European region, sample type, gender, and small mammal species on the observed prevalence estimates. A total of 76 studies were included in this study. The estimated pooled prevalence of Bartonella spp across small mammal populations in Europe was 30%. Notably, regional analysis revealed significant variations, with the highest prevalence observed in the Eastern region (43%). At the country level, Russia had the highest pooled prevalence of 65%, while Austria had the lowest estimated prevalence (5.7%). Although variations were observed in Bartonella spp prevalence among subgroups, this difference was not statistically significant (p-value > 0.05). A high diversity of Bartonella spp was observed in European small mammals with twenty-one Bartonella species detected, and nine of them being pathogenic to humans. The present study offers a comprehensive understanding of the eco-epidemiology of Bartonella spp in small mammal in Europe, providing insight into their role as reservoirs and potential vectors in the maintenance and transmission of Bartonella species.