Human pathogens in ticks removed from humans in Hebei, China

Abstract

Ticks are the hosts or vectors of many human pathogens, including viruses, bacteria and protozoa, and can transmit these causative agents to humans when feeding on human bodies. In this study, 26 ticks removed from humans in Hebei, China were tested for the presence of human-pathogenic microorganisms by Polymerase Chain Reaction (PCR) or Reversed Transcript PCR (RT-PCR). As a result, 11 ticks tested positive for at least one human pathogen. Specifically, four validated human pathogens, including Rickettsia raoultii, Candidatus Rickettsia tarasevichiae, Babesia venatorum, and Borrelia garinii, as well as Anaplasma ovis with zoonotic potential, were identified in Ixodes persulcatus, Dermacentor silvarum and Haemaphysalis concinna. Importantly, this is the first report of Anaplasma and Babesia species pathogenic to humans in Hebei province. Moreover, the co-infections, including double infection and quadruple infection were observed. In addition, Candidatus R. principis with unknown pathogenicity was identified in one tick, which may be the same species as Candidatus R. hongyuanensis based on the nucleotide identity and phylogenetic analysis. Concluding, four validated tick-borne pathogens and one with zoonotic potential were identified in ticks parasitizing humans, suggesting the potential high public health risk in the local human population.