Amblyomma americanum is an aggressive ixodid tick that has been implicated as a 
vector for several bacterial agents. Among these is Ehrlichia chaffeensis, which 
causes human monocytic (or monocytotropic) ehrlichiosis. In this study, 
experimental tick transmission of E. chaffeensis from infected lone star ticks 
to deer was revisited, and the question of whether it would be possible to 
re-isolate the organism from deer was asked, because this had not been done 
previously. Here, we were able to transmit a wild strain of E. chaffeensis from 
acquisition-fed lone star ticks to white-tailed deer. Ehrlichia chaffeensis was 
re-isolated from one white-tailed deer on multiple days during the infection and 
from another deer on one day during the infection. Peak rickettsemias for E. 
chaffeensis-infected deer were 17 DPI with acquisition-fed ticks and 14 DPI with 
needle-inoculated deer. This study supports the role of the lone star tick and 
white-tailed deer as vector and reservoir host for E. chaffeensis, demonstrating 
culture re-isolation of E. chaffeensis in deer infected by experimental tick 
transmission for the first time.