Molecular investigation of tick-borne pathogens in Ixodes ricinus feeding on lizards in the Central Pyrenees, Spain

Ixodes ricinus is the most widespread tick species in Europe, parasitizing a broad range of vertebrate hosts, including reptiles. However, the role of lizards in the ecology of tick-borne pathogens remains poorly understood. This study investigated tick infestation levels and the occurrence of tick-borne pathogens in I. ricinus feeding on European common lizards (Zootoca vivipara louislantzi) in the central Pyrenees, Spain. A total of 137 lizards were captured in summer and spring of 2024 at two sites (~ 1700 m.a.s.l.). Tick infestation prevalence was 98.5% and a mean abundance of 5.8 ± 7.0 ticks. Infestation was significantly higher in males, adults, and during spring. Molecular screening of 525 ticks (188 pools) using real-time and conventional PCR protocols detected Rickettsia spp. DNA in 15.4% pools, with an overall minimum infection rate (MIR) of 5.52%, with stage-specific MIRs of 4.79% in larvae and 7.81% in nymphs. Sequencing of 14 amplicons identified Rickettsia helvetica (n = 11) and Rickettsia monacensis (n = 3). Babesia DNA was detected at low prevalence (MIR: 0.38%) and sequences clustered within the Babesia divergens-Babesia capreoli complex. No Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum DNA was detected. Our findings show that lizards can sustain high levels of I. ricinus infestation, constituting a reliable bloodmeal source for ticks infected with Rickettsia and Babesia in the mountain ecosystems of the Pyrenees. Although the lizard's role in pathogen transmission remains to be clarified, its consistent exposure to immature ticks highlights its potential value as a sentinel species for monitoring tick-borne pathogen circulation in high-altitude environments.