Molecular epidemiology of relapsing fever and prevention of Borrelia infection

通过血玻片检查、媒介蜱巢式PCR和人血液样品，对坦桑尼亚中部一个村庄的人口进行了疏螺旋体属螺旋体调查。PCR在检测感染方面的灵敏度是前者的两倍，在11.1%的发热儿童和4.2%的其他健康儿童中发现了疏螺旋体。从18例感染中对疏螺旋体属进行基因分型，确定了杜通氏疏螺旋体和一个新的未命名物种，不知道来自人类或其他脊椎动物。系统发育分析与新大陆回归热疏螺旋体相似。这是坦桑尼亚中部蜱传回归热的一种新病原体，以前分离自感染房屋的猪鸟喙蜱。还从坦桑尼亚Dogs附近Mvumi使命村的房屋中收集了蜱虫。通过基于鞭毛蛋白基因的巢式聚合酶链反应检查所有蜱的疏螺旋体侵染。所有房屋均高度感染蜱虫，收集的所有蜱虫均为Ornithodoros porcinus种。120只蜱中有51只感染了螺旋体，鞭毛蛋白基因序列比较显示，大多数螺旋体属于杜氏疏螺旋体，杜氏疏螺旋体是东非蜱传回归热的病原体。其余的螺旋体与B有很大的不同。duttonii。这表明新的疏螺旋体是分布在该地区的回归热的病原体。使用16S核糖体RNA基因序列的系统发育分析也支持螺旋体是一个疏螺旋体物种不同于以前描述的属的成员。

The population of a central Tanzanian village were investigated for Borrelia sp. spirochaetes by blood slide examination, nested PCR for vector ticks and human blood samples. PCR was twice as sensitive in detecting infections, revealing Borrelia sp. in 11.1% of children with fever, and 4.2% of otherwise healthy children. Genotyping Borrelia sp. from 18 infections identified Borrelia duttonji and a new unnamed species, not known from humans or other vertebrates. Phylogenetic analysis of this Borrelia was resembled New World relapsing fever borreliae. Previously isolated from Ornithodoros porcinus ticks infesting houses, this is a new causative agent of tick-borne relapsing fever in Central Tanzania. Ticks were also collected from the houses in Mvumi Mission village, near Dodoma, Tanzania. All ticks were examined for Borrelia infestation by flagellin gene-based nested polymerase chain reaction. All houses were highly infested with ticks, and all ticks collected were of the Ornithodoros porcinus species. Fifty-one out of 120 ticks were infected with spirochetes, and a flagellin gene sequence comparison showed that most of the spirochetes belonged to Borrelia duttonii, which is the causative agent of tick-borne relapsing fever in East Africa. The rest of the spirochetes were quite different from B. duttonii. This indicates the new Borrelia is distributed and is causative agent of relapsing fever in the area. Phylogenetic analysis using 16S ribosomal RNA gene sequences also supported that the spirochete was a Borrelia species distinct from previously described members of the genus.