[Relapsing borrelioses fevers: forgotten and new ones].

Relapsing fever borrelioses are widely spread in the endemic regions of Eurasia, Africa, and America as before and account for significant morbidity and mortality; however, these infections have been recently underestimated. The pathogens of the fevers are the Borrelia species transmitted by ticks of the Ornithodoros genus; they genetically differ from the pathogens of Lyme borreliosis--Borrelia burgdorferi sensu lato transmitted by Ixodes ticks. The species Borrelia miyamotoi belongs to the genetic species of Borrelia, the causative agents of relapsing fevers. The authors found Borrelia of this species in the Ixodes ticks of Russia and first showed that B. miyamotoi were able to induce multiple cases in man, which had been earlier diagnosed as erythema-free Ixodes tick-borne borreliosis. The review considers the pathogenesis, clinical picture, diagnosis, and treatment of "old" relapsing fever borrelioses versus the available data on the "new" infection caused by B. miyamotoi. This must assist Russian physicians and scientists both to treat "old" and new tick-borne relapsing borrelioses and to schedule studies of the "new" B. myamotoi infection.