title: A new Borrelia species isolated from patients with relapsing fever in Spain.
abstract: BACKGROUND
  Lyme disease and tick-borne relapsing fever are worldwide systemic borrelioses caused by several Borrelia species transmitted by hard ticks (family Ixodidae) and soft ticks (family Argasidae), respectively. A previous seroepidemiological study of Lyme borreliosis showed several serologically reactive patients with clinically atypical presentations, and this discovery led to the hypothesis that some of the cases of Lyme borreliosis had been caused by another borrelia organism.
  
  
  METHODS
  Blood from patients in southern Spain who had suspected Lyme disease or relapsing-fever borreliosis was cultured before treatment began. Isolates of Borrelia spp were inoculated into several strains of mice of different ages. The 16S rRNA and flagellin in genes of Borrelia spp were sequenced by PCR and assessed by phylogenetic analyses.
  
  
  RESULTS
  We isolated a species of Borrelia from three patients with relapsing fever and from Ornithodorus spp ticks in southern Spain. This organism (refractory to in-vitro cultivation) caused a relapsing spirochaetaemia with multiple organ involvement in laboratory mice that recreated the human disease. Phylogenetic analysis showed that this organism is a previously unrecognised species.
  
  
  CONCLUSIONS
  We have discovered a new borrelia pathogen that is closely related to the other tick-borne agents of relapsing fever in Europe and Africa, and which causes a relapsing systemic disease with serological similarities to Lyme borreliosis.
authors.affiliation: Centro Nacional de Microbiología, Virología e Inmunología Sanitarias, Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Anda
authors.forename: W
authors.initials: W
authors.lastname: Sánchez-Yebra
authors.forename: M
authors.initials: M
authors.lastname: del Mar Vitutia
authors.forename: E
authors.initials: E
authors.lastname: Pérez Pastrana
authors.forename: I
authors.initials: I
authors.lastname: Rodríguez
authors.forename: N S
authors.initials: NS
authors.lastname: Miller
authors.forename: P B
authors.initials: PB
authors.lastname: Backenson
authors.forename: J L
authors.initials: JL
authors.lastname: Benach
mesh_terms: D000818:Animals; D001898:Borrelia / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D005408:Flagellin / Q000235:genetics; D006168:Guinea Pigs; D006801:Humans; D008193:Lyme Disease / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission; D051379:Mice; D008815:Mice, Inbred Strains; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012061:Relapsing Fever / Q000453:epidemiology* / Q000382:microbiology* / Q000635:transmission; D016036:Seroepidemiologic Studies; D013030:Spain / Q000453:epidemiology; D013987:Ticks / Q000382:microbiology
chemical_list: D012336:RNA, Ribosomal, 16S; D005408:Flagellin