Persistent Ehrlichia chaffeensis infection in white-tailed deer

Four white-tailed deer (Odocoileus virginianus) were inoculated intravenous ly with a deer-origin isolate (15B-WTD-GA) of Ehrlichia chaffeensis. The co urse of infection was monitored using indirect fluorescent antibody UFA), p olymerase chain reaction (PCR), and culture over a 9 m period. All deer bec ame rickettsemic within 24 days post inoculation (DPI), and all developed a ntibody titers >1:64 to E. chaffeensis by 17 DPI. Titers in all deer fell b elow 1:64 during 87 to 143 DPI. One deer exhibited a second period of serop ositivity (peak titer of 1:256) from 207 to 271 DPI but was culture and PCR negative during this period. Rickettsemia was confirmed by reisolation of E. chaffeensis as late as 73 to 108 DPI in three deer. Positive PCR results were obtained from femur bone marrow of one deer and from rumenal lymph no de of another deer at 278 DPI. None of the deer developed clinical signs, h ematologic abnormalities, or gross or microscopic lesions attributable to E . chaffeensis. Two uninoculated control deer were negative on all tests thr ough 90 DPI at which time they were removed from the study. Herein we confi rm that white-tailed deer become persistently infected, vith E. chaffeensis , have initial rickettsemias of several weeks duration and may experience r ecrudescence of rickettsemia, which reaffirm the importance of deer in the epidemiology of E. chaffeensis.