Objective To investigate the distribution of ticks, and the pathogen carriage status of ticks and host animals in Nanjing, Jiangsu province, in 2024, and assess the risk of tick-borne diseases transmission in Nanjing.

Methods From June to August in 2024, the questing ticks were collected using the flagging method in districts of Nanjing, while parasitic ticks were collected through visual inspection on animal bodies. Ticks were classified and identified by using stereomicroscope. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect Borrelia burgdorferi and Dabie bandavirus (DBV) in the ticks and host animals, while PCR was used to detect Rickettsia in the ticks and host animals.

Results A total of 460 tick samples were collected, with Haemaphysalis longicornis being the most abundant (348), followed by Haemaphysalis flava (110), Amblyomma testudinarium (1), and Ixodes hirstus (1). In the 213 parasitic tick samples, the tick index was 0.66. A total of 322 host animals from 5 species were monitored (goat, cat, dog, pig and chicken), in which goats had the highest tick index (2.38), followed by dogs. In the 247 free-living ticks, the density was 0.21 ticks/(flag·100 m). Eight habitats were monitored, in which suburban parks had the highest tick density 0.48 ticks/(flag·100 m). Pathogen detection in ticks and host animals revealed that the Rickettsia positive rate was 25.49% in ticks, no DBV or Borrelia burgdorferi were detected. And the DBV positive rate in host animals was 0.65%, no Rickettsia or Borrelia burgdorferi were detected.

Conclusion The predominant tick specieswas Haemaphysalis longicornis in Nanjing, the predominant host animal was goat, and the predominant habitat was suburban park. Positive samples for DBV and Rickettsia were detected, indicating the risks for the transmissions of severe fever with thrombocytopenia syndrome and Rickettsia disease in Nanjing.