Prevalence of pathogens in sympatric Ixodes ricinus and Dermacentor reticulatus ticks in Eastern Poland and their potential impact on oral-anal contacts between ticks.

Introduction and objective: Little is known about interspecific contacts between ticks. Therefore, this study focused on the investigation of factors that may influence interspecific contacts between Ixodes ricinus and Dermacentor reticulatus ticks.

Material and methods: Ixodes ricinus males and D. reticulatus females involved in oral-anal contacts (group I) and questing specimens with no such behaviour (group II) collected in eastern Poland were examined using molecular techniques to detect Borrelia burgdorferi s.l. (Bb), Rickettsia spp. (Rs), Anaplasma phagocytophilum, Babesia microti, and Toxoplasma gondii.

Results: An extremely high infection rate of Bb and Rs was determined in I. ricinus males (in groups I: 100% and 46.15% and group II: 90% and 40%, respectively) and D. reticulatus females (in group I: 84.61% and 61.53% and in group II: 90% and 20%, respectively). The prevalence of other pathogens in these ticks was substantially lower. Co-infection with pathogens was detected in approximately 53% of ticks.

Conclusions: The study suggests that tick-borne pathogens may have influenced the sexual behaviour of their vectors. The oral-anal contacts between I. ricinus and D. reticulatus ticks are probably stimulated by Bb and/or Rs. The presence of five pathogens and numerous co-infections in the analysed ticks indicates a risk of various human infectious diseases in the study region. Further studies are required to clarify the implications of oral-anal interspecific tick interactions.