First record of natural infection with Borrelia in ornithodoros (Ornithodoros) savignyi. Reservoir potential and specificity of the tick to Borrelia.

Field and laboratory data provided convincing evidence implicating O. savignyi at Shelateen, Halayeb province as a reservoir and a vector of a specific Borrelia. Using direct immunofluorescence Borrelia infection was detected for the first time in a natural population of O. savignyi in Egypt. The overall infection rate (IR) was relatively high (50.63%) and the infected ticks were capable of transmitting the infection to hamsters during feeding. Infected nymphs maintained borrelial infection transstadially to adults and the transstadially infected stages transmitted the spirochetes to hamsters. However, directly infected females were more efficient than males in transmitting the spirochetes to hamster and the IR of hamsters increased gradually by increasing the number of feeding infected ticks upon each hamster. Transovarial transmission of Borrelia intrinsic to O. savignyi occurred during the first and second gonadotrophic cycle of the infected females. The Borrelia sp. detected in the field collected O. savignyi showed specificity for its own natural tick host species when compared with B. crocidurae isolated from O. erraticus. Although the two tick species acquired, transstadially transferred and transmitted the two spirochetal infections, each tick species failed to transovarially transmit Borrelia isolated from the natural population of the other tick species.