Distribution Of Sheep Tick Species And Epidemiological Investigation Of Rickettsia

Hotan Prefecture in Xinjiang has the Kunlun Mountains to its south and the Taklimakan Desert to its north,with desert and Gobi covering 63% of its total area.The Hetian River,located within the region,is one of the four major tributaries of the Tarim River.Hotan Prefecture has a large area and a complex geographical environment.Ticks are hematophagous arthropods that parasitize the bodies of humans and animals.Rickettsia,a pathogen mainly transmitted by ticks,poses a potential threat to public health and human and animal safety.To investigate the distribution of tick species and the prevalence of Rickettsia in sheep in Hotan Prefecture,this study collected ticks from eight counties and cities in the area in 2022.A total of 2389 parasitic ticks were collected from Hetian City,Hetian County,Moyu County,Pishan County,Luopu County,Cele County,Yutian County,and Minfeng County in Hotan Prefecture.The ticks collected were preliminarily identified by morphology,and the 16 S rDNA gene fragment was amplified using PCR technology.The amplified PCR products were subjected to agarose gel electrophoresis and sent to GENEWIZ.for sequencing.After BLAST comparison and phylogenetic tree analysis,it was confirmed that the tick species obtained were Rhipicephalus turanicus、Hyalomma asiaticum、Dermacentor marginatus、Ornithodoros lahorensis and Dermacentor niveus.The extracted tick nucleic acid was amplified and sequenced using the sca1,geneD,and ompB genes,and the sequencing results were used to construct a phylogenetic tree using MEGA7.0software.The results showed the presence of Rickettsia,with a total prevalence of approximately57.81%.Among them,Moyu County had the highest prevalence rate of 73.08% and Luopu County had the lowest prevalence rate of 41.03% at the sampling sites.Comparative analysis revealed the presence of provisional Babesia Rickettsia,Rickettsia massiliae,and Rickettsia raoultii in ticks in this region,all of which have known homologous RickettsiaIn summary,a total of 2389 tick samples were collected in the study from eight counties in Hotan,Xinjiang,identifying five tick species including Rhipicephalus turanicus、Hyalomma asiaticum、Dermacentor marginatus、Ornithodoros lahorensis and Dermacentor niveus.PCR testing confirmed the presence of several types of rickettsia including Candidatus Rickettsia barbariae,Rickettsia massiliae,and Rickettsia raoultii in ticks parasitizing sheep in Hotan,with a total positive rate of 57.81%.The study demonstrated that the dominant tick species in Hotan is Haemaphysalis turanica and the prevalence of tick-borne rickettsia has been increasing in recent years.This study provides valuable data to understand the distribution of tick species and the prevalence of tick-borne rickettsia in Hotan,and provides a reasonable reference for the prevention and treatment of rickettsia in the future.