云南省3县(市)鼠类动物携带伯氏疏螺旋体调查

Investigation of Borrelia burgdorferi carried in rodents in three cities/counties of Yunnan Province

目的明确云南省3县(市)鼠类动物伯氏疏螺旋体携带情况及其影响因素,以期能科学有效防控人类莱姆病的发生和流行。方法2019年7—8月,在云南省弥勒市、芒市和梁河县16个自然村,采用夹夜法捕鼠,收集鼠脾脏组织并提取DNA。采用巢式PCR扩增伯氏疏螺旋体5S~23S rRNA基因目的片段,对阳性产物进行测序,所得序列作同源性比对和构建系统发育树。在R软件下应用χ^(2)检验或Fisher确切概率法分析鼠类动物在不同地区、生境、鼠种、鼠类性别、年龄及带蚤情况下携带伯氏疏螺旋体的情况。结果检测491份鼠类脾脏样本,11份扩增出伯氏疏螺旋体目的基因片段,携带率为2.24%,其中芒市1.58%,梁河县3.43%,弥勒市未检出。在3目3科3属4种鼠类动物中检测出伯氏疏螺旋体阳性,分别是灰麝鼩9.09%(1/11)、黄胸鼠3.27%(8/245)、大足鼠16.67%(1/6)和北树鼩7.69%(1/13)。不同生境鼠类动物携带伯氏疏螺旋体差异有统计学意义(P<0.05),其中来自灌木丛的鼠类动物携带率最高(7.29%),但不同地区、鼠种、鼠类性别、年龄及带蚤情况对鼠类动物携带伯氏疏螺旋体影响无统计学意义(P>0.05)。序列比对分析显示11份阳性样本基因序列与GenBank中收录的部分伯氏疏螺旋体5S~23S rRNA基因序列同源性达100%,进化分析显示与法雷斯疏螺旋体(Borrelia valaisiana)处在同一分支。结论云南省芒市和梁河县鼠类动物法雷斯疏螺旋体携带率不高,但对人有致病的风险,弥勒市鼠类动物本次未检出伯氏疏螺旋体。

Objective To investigate the carrier status of Borrelia burgdorferi in rodents in three counties of Yunnan and to identify influencing factors,to provide a scientific basis for effective control and prevention of human Lyme disease.Methods From July to August 2019,rodents were collected by night trapping method from 16 natural villages across Mile City,Mangshi City,and Lianghe County in Yunnan.Spleen tissue samples were collected,and DNA was extracted.The target fragment of Borrelia burgdorferi 5S-23S rRNA gene was amplified by nested PCR,and positive products were sequenced.The sequences were homologous compared and a phylogenetic tree was constructed.The Chi-square test or Fisher's exact probability method was applied in R software to analyze the presence of Borrelia burgdorferi in rodents in different regions,habitats,species,genders,ages,and flea statuses.Results A total of 491 spleen samples were tested,from which 11 amplified the target gene fragment of Borrelia burgdorferi,with a carriage rate of 2.24%.Among them,the carriage rates in Mangshi City and Lianghe County were 1.58%and 3.43%,respectively,while no B.burgdorferi was detected in Mile City.Positive cases of Borrelia burgdorferi were detected in 4 species of rodents from 3 orders,3 families,and 3 genera:Crocidura attenuata(9.09%,1/11),Rattus tanezumi(3.27%,8/245),Rattus nitidus(16.67%,1/6),and Tupaia belangeri(7.69%,1/13).There was a statistically significant difference in Borrelia burgdorferi carried among rodents from different habitats(P<0.05),with the highest carrying rate(7.29%)found in rodents from bushes.No significant differences were observed in carriage rates across different regions,species,genders,ages,or flea statuses(all P>0.05).Sequence alignment analysis revealed that the gene sequences of 11 positive samples showed 100%homology with some of the 5S-23S rRNA gene sequences of Borrelia burgdorferi included in GenBank.Evolutionary analysis showed that they clustered in the same branch as Borrelia valaisiana.Conclusions The carriage rate of Borrelia valaisiana in rodents from Mangshi City and Lianghe County in Yunnan Province is low,but there remains a potential risk to human health.No Borrelia burgdorferi was detected in rodents from Mile City.