A. Portillo, V. Ibarra, S. Santiba´n˜ez, L. Pe´rez-Marti´nez, J. R. Blanco and J. A. OteoA´ rea de Enfermedades Infecciosas, Hospital San Pedro-Centro de Investigacio´n Biome´dica de La Rioja(CIBIR), La Rioja, SpainRickettsiosis are emerging and re-emerging infec-tions distributed all over the world. In the lastyears ‘new’ Rickettsia species have been involvedas human pathogens [1–3]. Candidatus Rickettsiarioja is a ‘new’ spotted fever group Rickettsiainvolved in Dermacentor-borne necrosis erythemaand lymphadenopathy (DEBONEL) or tick-borne-lymphadenopathy (TIBOLA) cases from Spain[4,5]. In 2006, a fragment of the ompA gene fromEDTA-treated blood of two patients who devel-oped DEBONEL after being bitten by Dermacentormarginatus in La Rioja, was submitted to GenBank(GenBank accession no. EF028201). This Rickettsiaspecies has also been amplified from ticksremoved from patients with DEBONEL.The aim of this study was to characterise thenucleotide sequence of ompA, ompB, citrate sintase(gltA) and 17 KDa genes from Candidatus R. rioja.As part of a retrospective study, 15 DNA extractsused for ompA PCR that showed 98% similaritywith Rickettsia raoultii and with uncultured Rick-ettsia sp. RpA4, DnS14 and DnS28, were furtheranalysed for the presence of ompB, gltA and17 KDa. Specimens were obtained from twoblood samples and nine D. marginatus removedfrom DEBONEL patients and from four D. mar-ginatus removed from asymptomatic people.For our 15 specimens, when ompA nucleotidesequences were compared with GenBank data,>99% similarity was found with Candidatus Rick-ettsia rioja (Fig. 1). Unfortunately, all attempts toamplify ompB and gltA genes from the two bloodsamples failed. However, PCR amplicons forompB and gltA were obtained from 12⁄13D. marginatus (92.3%). Subsequent sequence anal-ysis of ompB PCR products showed highestsimilarity ( 99% identity with Candidatus R. rioja. For theompB and gltA amplicons obtained from 12D. marginatus, highest identities for ompB andgltA were found with partial genes from R. raoultii(<98.9% and <99.7%, respectively). These com-parisons suggest that Candidatus R. rioja can beconsidered a new Rickettsia species as soon as anestablished isolate is available.ACKNOWLEDGEMENTS