Prevalence and genetic diversity of Babesia microti in rodents from central and southern Shanxi, China.

BACKGROUND

Babesiosis, a globally emerging tick-borne zoonosis caused by intraerythrocytic protozoan Babesia species, poses a significant threat to both animal and human health. This study investigated the prevalence and genetic diversity of Babesia sp. in small rodents in central and southern Shanxi Province, China.

METHODS

Rodents were captured from central and southern Shanxi Province, China. Liver, spleen, and kidney specimens were collected and screened for Babesia sp. based on 18S rRNA gene amplification and sequencing. For genetic and evolutionary analysis of Babesia sp. sequences based on the 18S rRNA gene, a phylogenetic tree was created using MEGA 11. Genetic diversity was analyzed using DNASP 6.12.03, and haplotype networks in Babesia microti from different regions and hosts were constructed using PopART software.

RESULTS

Three hundred and one rodents were captured; PCR screening revealed a 6.64% (20/301) prevalence of Babesia sp. infection, detected in Niviventer confucianus (16.87%, 14/83) and Apodemus agrarius (3.85%, 6/156). Detection rates did not differ significantly according to sex, tissue, or habitat type. Geographically, central Shanxi exhibited significantly higher detection rates than southern Shanxi (9.74% vs. 0.94%, χ = 8.573, P = 0.003). Phylogenetic analysis of the partial 18S rRNA gene (1083 bp) confirmed that all sequences obtained in this study were the B. microti Kobe type, closely related to sequences from southeastern Shanxi obtained in our previous study (with 99.7-100% identity), with the ability to infect humans. Genetic diversity analysis of 65 B. microti sequences from China (20 sequences from the present study and 45 from GenBank) identified 21 haplotypes with host- and geography-specific patterns. Host-specific analysis of 18S rRNA gene polymorphisms revealed higher genetic diversity in tick-derived sequences than in rodent- or human-derived sequences. Haplotype network analysis suggested that Shanxi sequences (Hap-1, Hap-10, and Hap-11) exhibited close genetic proximity of 1-3 nucleotide substitutions with rodent-derived sequences from Yunnan and Fujian provinces and human-derived sequences from Yunnan and Zhejiang provinces.

CONCLUSIONS

This study found a high prevalence and low genetic diversity of B. microti infection in wild rodents in central Shanxi, which could provide a basis for local corresponding prevention and control strategies.