Novel Ehrlichia organism (Rickettsiales : Ehrlichieae) in white-tailed deer associated with lone star tick (Acari : Ixodidae) parasitism

Polymerase chain reaction (PCR) evidence of a novel Ehrlichia organism was found recently in wild white-tailed deer, Odocoileus virginianus Zimmermann , and lone star ticks, Amblyomma americanum L., from the southeastern Unite d States. To evaluate whether lone star tick parasitism was associated with the presence of this novel Ehrlichia organism in deer, 2 retrospective stu dies were conducted using specific nested PCR to test archived Jeer serum s amples. The Ist study of 150 serum samples collected from a single deer pop ulation over a 15-yr period examined the temporal association between the p resence of the Ehrlichia organism in deer and parasitism by lone star ticks . The deer Ehrlichia was not detected in serum samples collected be fore 19 86, when lone star ticks were absent or rare, but was detected in samples c ollected in 1986 and every year thereafter, when lone star ticks became inc reasingly abundant. In the end study, serum samples from 120 deer from 24 s ites in 14 southeastern states were tested to evaluate if a site-specific, spatial association existed between the presence of the deer Ehrlichia and lone star ticks. All GO serum samples from the 12 Jeer populations without evidence of lone star tick infestation were negative for the deer Ehrlichia , whereas 83% of the 12 populations infested by lone star ticks had PCR evi dence of infection. These data suggest that lone star ticks may be a vector of the deer Ehrlichia; however, they do not preclude the involvement of ot her arthropods in maintaining infection with this organism in deer populati ons.