EXPERIMENTAL TRANSMISSION OF EHRLICHIA-CHAFFEENSIS (RICKETTSIALES, EHRLICHIEAE) AMONG WHITE-TAILED DEER BY AMBLYOMMA-AMERICANUM (ACARI, IXODIDAE)

Ehrlichia chaffeensis Anderson, Dawson and Wilson, causative agent of human (predominantly monocytic) ehrlichiosis, was successfully transmi tted experimentally by Amblyomma americanum (L.) to white-tailed deer, Odocoileus virginianus (Zimmerman). Deer were needle-exposed intraven ously to E. chaffeensis in tissue-culture canine macrophage (DH82) cel ls, and 11 d later were exposed to laboratory-reared A. americanum lar vae, nymphs, and adults for acquisition feeding. Three months after th is feeding, naive deer and dogs were exposed to recently molted nymphs and adults. Attempted reisolation of the pathogen by way of tissue cu lture was successful from one needle-exposed deer but not from the tic k-exposed deer or dogs. Based on serologic evidence and polymerase cha in reaction data, both nymphal and adult ticks transmitted E. chaffeen sis to naive deer but not to dogs.