Experimental Infection of Mice and Ticks with the Human Isolate of NY-18.

is the causative agent of tick-borne fever (TBF) and human granulocytic anaplasmosis (HGA) and is currently considered an emerging disease in the USA, Europe, and Asia. The increased prevalence of as a human pathogen requires the detailed characterization of human isolates and the implementation of appropriate animal models. In this study, we demonstrated that the dynamics of infection with the human isolate of NY-18 was variable in three different strains of mice (SCID, C3H/HeN, BALB/c). We further evaluated the ability of to acquire and transmit NY-18 and compared it with . Larvae of both tick species effectively acquired the pathogen while feeding on infected mice. The infection rates then decreased during the development to nymphs. Interestingly, molted nymphs were unable to transmit the pathogen to naïve mice, which contrasted with . The results of our study suggest that is not a competent vector for the American human isolate. Further studies are needed to establish reliable transmission models for and European human isolate(s) of .