IXODES-DAMMINI AS A POTENTIAL VECTOR OF HUMAN GRANULOCYTIC EHRLICHIOSIS

Little is known about the epidemiology and mode of transmission of the agent of human granulocytic ehrlichiosis (HGE), Analyses of an engorg ed female Ixodes dammini tick removed from an HGE patient and 101 fiel d-collected I. dammini and Dermacentor variabilis from three Wisconsin counties for Borrelia burgdorferi and Ehrlichia phagocytophila/Ehrlic hia equi DNA revealed that the patient tick and 7 of 68 I. dammini tic ks from Washburn County collected in 1982 and 1991 were positive for e hrlichial DNA; 10 ticks from the same collections were positive for B. burgdorferi. Two specimens (2.2%) were positive for both organisms. S erologic evidence for exposure to the agent of HGE or its relatives wa s detected in 3 of 25 Lyme disease patients from the upper Midwest. Th ese data argue that I. dammini is a common vector for transmission of both Lyme disease and HGE.