NATURAL COINFECTION OF A WHITE-TAILED DEER (ODOCOILEUS-VIRGINIANUS) POPULATION WITH 3 EHRLICHIA SPP

The ticks Amblyomma americanum and Ixodes scapularis, strongly implica ted vectors of Ehrlichia chaffeensis and the human granulocytic ehrlic hiosis (HGE) agent, respectively, commonly are found on white-tailed d eer (Odocoileus virginianus). As deer can be infected with E, chaffeen sis, the HGE agent, and another Ehrlichia-like organism, a deer popula tion parasitized by both tick species in coastal Georgia was tested fo r evidence of Ehrlichia spp. infection using serologic, molecular, and culture techniques. Antibodies to both E. chaffeensis (geometric mean titer = 111) and Ehrlichia equi, surrogate antigen for the HGE agent, (geometric mean titer = 1,024) were detected by indirect fluorescent antibody testing. Nested polymerase chain reaction employing species-s pecific primers demonstrated sequence-confirmed 16S rDNA fragments of 3 distinct Ehrlichia spp. in this population: E. chaffeensis (1/5), th e HGE agent (3/5), and an Ehrlichia-like organism previously described from white-tailed deer (5/5). Ehrlichia chaffeensis was isolated in c ulture from the inguinal lymph node of a single deer. An Ehrlichia-typ e morula was identified in a neutrophil of 1 deer on examination of bl ood smears. This work provides the first evidence of the HGE agent in a nonhuman host in the southeastern United States and documents infect ion with both E. chaffeensis and the HGE agent in a single deer popula tion, thereby supporting the importance of white-tailed deer in the na tural history of the human ehrlichioses agents.