title: Population structure of East African relapsing fever Borrelia spp.
abstract: Differentiation of endemic East African tick-borne relapsing fever Borrelia duttonii spirochetes from epidemic louse-borne relapsing fever (LBRF) B. recurrentis spirochetes into different species has been questioned. We assessed a noncoding intragenic spacer (IGS) region to compare genotypes found in clinical samples from relapsing fever patients. Although IGS typing was highly discriminatory and resolved 4 East African tick-borne relapsing fever groups from a disease-endemic region in Tanzania, 2 IGS clades were found among LBRF patients in Ethiopia. The 2 IGS sequence types for B. recurrentis overlapped with 2 of the 4 groups found among B. duttonii. All cultivable isolates of B. duttonii fell into a single IGS cluster, which suggests their analysis might introduce selective bias. We provide further support that B. recurrentis is a subset of B. duttonii and represents an ecotype rather than a species. These observations have disease control implications and suggest LBRF Borrelia spp. could reemerge from its tick-borne reservoirs where vectors coexist.
authors.affiliation: University of East London, Water Lane, Stratford, London E15 4LZ, UK. s.cutler@uel.ac.uk
authors.forename: Sally J
authors.initials: SJ
authors.lastname: Cutler
authors.forename: E Margarita
authors.initials: EM
authors.lastname: Bonilla
authors.forename: Rajbir J
authors.initials: RJ
authors.lastname: Singh
mesh_terms: D001782:Blood Donors; D001898:Borrelia / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D021901:DNA, Intergenic / Q000737:chemistry; D006801:Humans; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012061:Relapsing Fever / Q000382:microbiology*
chemical_list: D021901:DNA, Intergenic