Molecular Detection and Phylogenetic Analysis of Anaplasma Species in Ticks from Three Provinces of China

Background: Anaplasmosis, caused by Anaplasma species, poses significant threats to public health and livestock productivity. Understanding the distribution and genetic diversity of these pathogens in tick vectors across China is critical for risk assessment and disease control. Materials and Methods: From April to June 2023, 875 ticks were collected across three Chinese provinces: Jiangxi, Yunnan, and Shaanxi. The collected ticks comprised Rhipicephalus microplus (from Jiangxi and Yunnan) and Haemaphysalis longicornis (from Shaanxi). Pathogen detection was performed using PCR, followed by phylogenetic analysis of the obtained sequences to determine genetic relationships. Results: Anaplasma capra was detected predominantly in R. microplus from Yudu County, Jiangxi (4.95%), and in H. longicornis from Meixian County (3.16%), Long County (5.99%), and Zhenba County (0.83%) in Shaanxi, exhibiting regional genetic variations. The detection rate of Anaplasma marginale was 6.59% in Yudu County, Jiangxi; significantly higher rates were found in Yunnan province: 41.75% in Nanjian County, 40.38% in Weishan County, and 52.04% in Yongsheng County. Phylogenetic analysis revealed that A. marginale isolates from Lijiang (Yongsheng), Yunnan, were highly homologous (99.63%-100%) to those from Yudu County, Jiangxi, while isolates from Dali (Nanjian and Weishan), Yunnan, formed a distinct clade. Conclusion: The findings demonstrate the widespread distribution of A. capra and A. marginale in ticks across the surveyed regions of China, with notable variations in prevalence and genetic characteristics. These pathogens represent potential threats to local residents and livestock. Future research should expand the geographic sampling range to fully understand their distribution patterns and explore effective prevention and control strategies to safeguard public health and safety.