Identification of new microfoci of <i>Ixodes pavlovskyi</i> and associated tick-borne microorganisms in Northeastern China

Ixodes pavlovskyi is a bird-associated tick species widely distributed in Russia and Japan, but has been rarely reported in China since its initial record in 1959. In this study, we conducted a comprehensive field investigation in 2022 at two forested sites in Harbin, Heilongjiang Province, northeastern China. A total of 1,063 questing ticks were collected and identified using molecular methods. Ixodes pavlovskyi accounted for 54.25% of ticks in Xiaoling Subdistrict but only 1.16% in Pingshan Town. COI-based phylogenetic and haplotype network analyses (n = 36) revealed that Chinese I. pavlovskyi shared haplotypes with Japanese populations but was genetically distinct from Russian (Western Siberia) populations. Pairwise FST values between Chinese and Japanese haplotypes were 0.04682, indicating no detectable genetic differentiation. Molecular screening identified Candidatus Rickettsia tarasevichiae, R. raoultii, Candidatus R. principis, and Borrelia garinii in I. pavlovskyi specimens. A systematic review of tick surveillance studies (2021–2025) across five surrounding provinces revealed no reports of I. pavlovskyi. These findings support the hypothesis that migratory birds may facilitate the long-distance spread of I. pavlovskyi and its associated pathogens, highlighting their potential role in the transboundary dissemination of tick-borne diseases.