Danielle R. Troughton, Michael L. Levin

Viral and Rickettsial Zoonoses Branch, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA: dross@cdc.gov

We studied the dynamics of Anaplasma phagocytophilum in infected Ixodes scapularis nymphs throughout their engorgement on uninfected mice. Nymphs were placed on BALB/c mice and allowed to feed for intervals between 4 and 72 hours. Ticks were removed at certain intervals and tested by quantitative PCR to determine the amount of A. phagocytophilum present at each time point. The average amount of A.phagocytophilum DNA gradually increased from 1.53 x 106 to 2.43 X 1010 copies of DNA per tick over the duration of the nymphal feeding period. The significance of these findings will be discussed in the context of our data on pathogen dynamics seen in the transstadial molt from the larval stage and on the infectivity of resulting nymphs.