Abstract:

Objective To study the infection status of Rickettsia typhi in rodents on Heixiazi Island at the Sino-Russian Border. Methods Rodents were captured by night trap on the Heixiazi Island between 2013 and 2014, liver tissues were processed by aseptic operation and the genomic DNA were extracted from them. Rickettsia typhi strains were confirmed by nest polymerase chain reaction (nest-PCR) of the 136 bp gltA gene. The positive amplification products were sequenced and compared with other R. typhi strains in GenBank, then phylogenetic analyses were drafted by software Mega 5.0. Results A total of 644 rodents were captured, which belong to 3 orders 5 family 8 genera. Apodemus agrarius which was the predominant species, accounting for 42.70% (275/644), followed by Clethrionomys rutilus (178/644, 27.64%) and Microtus fortis (136/644, 21.12%). The infection rate of R. typhi was 4.81%, with 31 rodent samples detected positive, which belong to 5 species. The infection rate of M. fortis (13/136, 9.56%) was relatively high, but no significant difference was found between the infection rate and the species of rodents by Fisher's exact probability (P=0.156). Although the infection rate of females (10/168, 5.95%) was higher than males (21/476, 4.41%), no significant difference of sex on the infection of R. typhi (χ²=0.643, P=0.423). There was no significant difference of weight on the infection of R. typhi (F=1.633, P= 0.202). However, there was significant difference of captured time on the infection of R. typhi (χ²=191.419, P=0.000). All the R. typhi in rodents on this region were in the same phylogenetic branch with a high similarity of above 99.98%,close with the USA strain CP003398 by the similarity above 95.83%. Conclusion The investigation proved that R. typhi is probably prevalent in rodents on Heixiazi Island at the Sino-Russian Border. The infection rate in rodents was significant difference in captured time. This study provides the basis for scientific development of Heixiazi Island in the future.

Key words: Rodents, Rickettsia typhi, Epidemiology, Heixiazi Island

摘要：

目的 调查中俄边境黑瞎子岛地区鼠群斑疹伤寒立克次体的感染状况。方法 于2013－2014年在黑瞎子岛地区采用夹夜法捕鼠,无菌取其肝脏组织,提取鼠肝脏总核酸,采用巢式聚合酶链反应(nest-PCR)技术,对提取的鼠肝脏总核酸中gltA 基因的136 bp特异性片段进行扩增,对阳性扩增产物测序,并利用Mega 5.0软件与GenBank中已知菌株基因序列进行比对和系统发育分析。结果 共捕鼠644只,隶属于3目5科8属,其中黑线姬鼠为优势鼠种,占捕获总数的42.70%(275/644),其次为红背鼠平和东方田鼠,分别占27.64%(178/644)和21.12%(136/644)。共检出31只鼠感染斑疹伤寒,阳性率为4.81%,分属于啮齿目中5种鼠,其中东方田鼠的感染率相对较高,为9.56%(13/136),其他啮齿目鼠形动物感染率相对较低,但各鼠种间感染率差异无统计学意义(P=0.156)。雌鼠的感染率(10/168,5.95%)虽高于雄鼠(21/476,4.41%),但差异无统计学意义(χ²=0.643,P=0.423)。斑疹伤寒感染组体重均值(38.2548 g)与非感染组的体重均值(32.2271 g)差异无统计学意义(F=1.633,P=0.202)。不同捕鼠时间鼠斑疹伤寒的感染率差异有统计学意义(χ²=191.419,P=0.000)。该地区鼠群感染的斑疹伤寒立克次体在同一进化支上,相似度> 99.98%,与美国菌株CP003398在进化上最为相近,相似度> 95.83%。结论 黑瞎子岛地区鼠群存在斑疹伤寒立克次体感染,且感染状况存在季节性差异,为科学开发黑瞎子岛提供了依据。

关键词: 鼠形动物, 斑疹伤寒立克次体, 流行病学, 黑瞎子岛