Prevalence of the Rickettsial Agent of Human Granulocytic Ehrlichiosis in Ticks from a Hyperendemic Focus of Lyme Disease

To the Editor: Human granulocytic ehrlichiosis, a newly discovered tick-borne infection originally described in the upper Midwest,1 has recently been reported in 29 patients from Westchester County, New York.2 We used the polymerase chain reaction (PCR) to examine 173 host-seeking ticks (Ixodes scapularis) collected from vegetation in Westchester County for the presence of the agent of human granulocytic ehrlichiosis, as well as the agent of Lyme disease, Borrelia burgdorferi. After extracting DNA from dissected tissues, we used the 23S ribosomal DNA (rDNA) primers of Schwartz et al.3 for B. burgdorferi and the 16S rDNA primers of Pancholi . . .