[Investigation of tick species in Suizhou City, Hubei Province from 2023 to 2024].

Abstract

Objective: To investigate the species of ticks in Suizhou City, Hubei Province, so as to provide insights into management of ticks and tick-borne diseases.

Methods: During the period between May 2023 and June 2024, livestock breeding farms and vegetation neighboring the place of residence of confirmed and suspected patients with tick-borne disease were selected as sampling points in rural areas from Yindian Township, Gaocheng Township, Wanhe Township, Wushan Township, Xiaolin Township, Xihe Township, Hedian Township and Beijiao Street in Suizhou City, Hubei Province, where confirmed and suspected cases with tick-borne diseases had been reported. The parasitic ticks on the body surface of free-range livestock were captured with tweezers in livestock breeding farms, and free ticks on the vegetation surface were captured with the flagging method. Morphological identification of tick samples was performed under a microscope, and the gender and developmental stage of ticks were determined. One engorged adult tick, 2 to 3 blood-feeding but non-engorged adult ticks, 10 to 15 unfed female ticks, 15 to 20 unfed male ticks, and 30 to 40 tick nymphs or larvae were assigned into a group, respectively. Genomic DNA was extracted from tick samples in each group, and mitochondrial 16S rRNA gene was amplified. Sequence analysis was performed with the DNASTAR software, and phylogenetic analysis was performed using the software MEGA 7.0. In addition, the phylogenetic tree was generated using the maximum likelihood method based on the Kimura 2 parameter model.

Results: A total of 2 438 ticks were captured from Suizhou City, Hubei Province during the period between May 2023 and June 2024, including 595 free ticks and 1 483 parasitic ticks. Three developmental stages of ticks were captured, including larvae, nymphs, and adults, and 75.18% (1 899/2 438) of captured ticks were adult, in which 79.04% (1 501/1 899) were female. Morphological and molecular biological assays identified one family, three genera and four species of captured ticks, including 2 425 Haemaphysalis longicornis ticks (99.47%) and one H. flava tick (0.04%) of the genus Haemaphysalis, 11 Rhipicephalus microplus ticks (0.45%) of the genus Rhipicephalus, and one Ixodes sinensis tick (0.04%) of the genus Ixodes in the family Ixodidae. Phylogenetic analysis revealed that the H. longicornis sequence (SZ49) in this study was clustered with sequences from Yunnan Province (GenBank accession number: MH024510.1), Hebei Province (GenBank accession number: MK450606.1) and Henan Province (GenBank accession number: MZ230645.1) into a clade, and the H. flava sequence (SZ19) in this study was clustered with sequences from Japan (GenBank accession number: MW064044.1), South Korea (GenBank accession number: ON629585.1), and Jiangsu Province (GenBank accession number: PP494741.1) and Hebei Province of China (GenBank accession number: MH520685.1) into a clade, while the R. microplus sequence (SZ8) in this study was clustered with the sequences from India (GenBank accession number: MK621328.1), and Henan Province (GenBank accession number: MT555307.1) and Guizhou Province of China (GenBank accession number: PP446801.1) into a clade. The sequence of I. sinensis (SZ23) in this study had 99.51% homology with that (GenBank accession number: OM368265.1) of ticks sampled from Wuhan City, Hubei Province.

Conclusions: There are four tick species of H. longicornis, H. flava, R. microplus and I. sinensis in Suizhou City, Hubei Province, and H. longicornis is the dominant species. H. flava is firstly recorded in Suizhou City.