Analysis of pathogen co-occurrence in host-seeking adult hard ticks from Serbia

Past studies in Serbia have reported concurrent infections of Ixodes ricinus ticks with Borrelia burgdorferi sensu lato genospecies, Anaplasma phagocytophilum and Francisella tularensis . As a step forward, this investigation included a broader range of microorganisms and five most common and abundant tick species in Serbia. Five tick species were identified ( Dermacentor marginatus , D. reticulatus , Haemaphysalis punctata , H. concinna and I. ricinus ) and analyzed for the presence of seven pathogens. Anaplasma ovis , A. phagocytophilum , Babesia canis , B. burgdorferi s.l., Coxiella burnetii , Rickettsia helvetica and R. monacensis were detected. Sequencing of samples positive for F. tularensis revealed the presence of Francisella -like endosymbionts. No Bartonella spp. DNA was amplified. Concurrent infections were present in three tick species ( D. reticulatus , H. concinna and I. ricinus ). The rate of co-infections was highest in I. ricinus (20/27), while this tick species harbored the broadest range of co-infection combinations, with dual, triple and a quadruple infection(s) being detected.