Variety of Bacterial Pathogens in Ticks Removed from Humans, Northeastern China.

Ticks transmit diverse pathogens, posing significant public health threats in northeastern China; clarifying human-biting tick species and their carried pathogens is crucial for risk assessment and prevention. This study was designed as a pathogen detection and molecular epidemiological investigation. During the May-August period of each of 2023 and 2024, 232 ticks that had bitten humans were collected from a local sentinel hospital. Ticks were morphologically identified, followed by DNA extraction, semi-nested/nested PCR targeting specific genetic markers, and Sanger sequencing to detect bacterial pathogens. Four tick species were found, with Ixodes persulcatus dominant (87.9%), followed by Dermacentor silvarum (6.9%), Haemaphysalis concinna (3.5%), and Haemaphysalis japonica (1.7%). Seven bacterial pathogens were detected, including Candidatus Rickettsia tarasevichiae (35.3%) and Borreliella garinii (17.2%); 49.6% of ticks were pathogen-positive. The coinfection rate was 13.8%, most commonly Candidatus R. tarasevichiae plus B. garinii, and I. persulcatus carried all pathogens. These findings provide basic data on human-biting tick species and their bacterial pathogen spectrum in the region, serving as a reference for subsequent tick-borne disease research and targeted prevention.