黑龙江中俄边境口岸全沟硬蜱中分离到人巴贝西原虫

Babesia Microti-like Rodent Parasites Isolated from Ixodes Persulcatus (Acari:Ixodidae) at China-Russia Ports of Heilongjiang Province

〔目的〕了解中俄边境口岸人巴贝西原虫在蜱体内的感染携带情况及病原基因特征,以便采取必要的防控措施。〔方法〕用从黑龙江中俄边境口岸采集到的全沟硬蜱叮咬清洁级的SCID小鼠,而后,利用微气固相分离技术从被叮咬的SCID小鼠中分离人巴贝西原虫。〔结果〕涂片观察可见血细胞内呈现典型的四分体和环状体。离体培养血细胞中亦观察到人巴贝西原虫的生长。核糖体小亚基的基因序列分析表明,新分离到的人巴贝西原虫是微小巴贝西原虫,与密山株和日本神户株具有高度同源性。本批样本中,雌性全沟硬蜱的感染率为2.7%～4.0%。〔结论〕中俄边境口岸存在人巴贝西原虫的自然疫源地,存在人感染的风险,检验检疫部门应采取必要的防范措施,防止巴贝西原虫病传入传出。

Objective To explore the fact that the China-Russia border of Heilongjiang province had been a human Babesia disease natural focus,to isolate a Babesia microti-like rodent parasite from the tick,and to collect Ixodes persulcatus from the forest area of Heilongjiang province.Methods The collected Ixodex persulcatus were allowed to feed on specific pathogen-free SCID mice and red blood cells from the mice were used to isolate Babesia spp.with the microareophilous stationary-phase culture technique.Results Paired and tetrad forms of merozoites were observed by light microscope in red blood cells of SCID mice.In vitro growth of the parasites was also achieved in mice erythrocytes,which indicated the presence of Babesia spp.in Ixodex persulactus.To further identify the Babesia species,polymerase chain reaction screening and subsequent sequencing of nuclear small subunit ribosomal RNA （nssrRNA） was employed.The results indicate that the observed parasites might be an isolate strain responsible for human babesiosis Babesia microti-which has 99.3% identity with that of Babesia microti isolate RcM5201 （AB112050） from Mishan in Heilongjiang and Kobe isolates from Japan.In addition,the infection rate of Babesia microti in Ixodex persulcatus ticks in the region was 2.7%～4.0% in adult females and no infection in males.Conclusion Though the infection rate is low,the high attack frequency of tick species on local residents indicates the risk of human babesiosis in the region and the necessary of precautionary measures.