Ehrlichiosis is caused by specialized bacteria called rickettsiae. HME is caused by Ehrlichia chaffeensis . HGE is caused by a newly identified but as yet unnamed Ehrlichia . In the United States, HME has so far been concentrated in the southeast and south-central regions. HGE has been found mainly in the upper midwestern and northeastern states, but also in northern California.
People get ehrlichiosis from the bite of an infected tick.
The deer tick also spreads Lyme disease and babesiosis. The disease is similar to Rocky Mountain spotted fever and can be severe and life-threatening. The most common symptoms are sudden high fever, tiredness, major muscle aches, severe headache, and, in some cases, a rash. Symptoms usually appear 3 to 16 days after a tick bite. Diagnosis is difficult, even in severe cases.