Human monocytic ehrlichiosis (HME) is a rickettsial disease characterized by fever, headache, muscle aches and pain, anorexia, abdominal pain, and confusion occurring 1 to 3 weeks following the bite of an infected lone star tick, Amblyomma americanum. The probable reservoirs are the white-tailed deer, Odocoileus virginianus, and wild rodents. Infection prevalence of the causative agent Ehrlichia chaffeensis in lone star ticks is about 12%, while the prevalence of E ewingii, a similar ehrlichial pathogen, is approximately 8%. The American dog tick is considered a secondary vector of E chaffeensis. Over 10 cases of HME have been reported annually in New Jersey since 1995.