Typing African Relapsing Fever Spirochetes
Published Date:Nov 2005
Source:Emerg Infect Dis. 11(11):1722-1729.
Bacterial Typing Techniques
DNA, Ribosomal Spacer
Intragenic Spacer Molecular Typing
Louseborne Relapsing Fever
Molecular Sequence Data
RNA, Ribosomal, 16S
RNA, Ribosomal, 23S
Sequence Analysis, DNA
Tickborne Relapsing Fever
Description:Relapsing fever Borrelia spp. challenge microbiologic typing because they possess segmented genomes that maintain essential genes on large linear plasmids. Antigenic variation further complicates typing. Intergenic spacer (IGS, between 16S-23S genes) heterogeneity provides resolution among Lyme disease-associated and some relapsing fever spirochetes. We used an IGS fragment for typing East African relapsing fever Borrelia spp. Borrelia recurrentis and their louse vectors showed 2 sequence types, while 4 B. duttonii and their tick vectors had 4 types. IGS typing was unable to discriminate between the tick- and louseborne forms of disease. B. crocidurae, also present in Africa, was clearly resolved from the B. recurrentis/B. duttonii complex. IGS analysis of ticks showed relapsing fever Borrelia spp. and a unique clade, distant from those associated with relapsing fever, possibly equivalent to a novel species in ticks from this region. Clinical significance of this spirochete is undetermined.
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