The first human case in the U.S. was reported in 1986, in a man exposed to ticks in Arkansas. In New York State, most cases of ehrlichiosis have been diagnosed in Westchester County and the lower Hudson valley. Anyone can get ehrlichiosis, although the majority of known cases have been in adults. People who spend time outdoors in tick infested areas from April until October are at greatest risk for exposure. As with Lyme disease, ehrlichiosis is believed to be spread by ticks, including the deer tick, the dog tick and the lone star tick.
Transmission occurs after a bite from an infected tick.
Ehrlichiosis cannot be spread from person to person. The most common symptoms are fever, muscle aches, weakness and headache. Patients may also experience confusion, nausea, vomiting and joint pain. Unlike Lyme disease or Rocky Mountain spotted fever, a rash is not common. Infection usually produces mild to moderately severe illness, with high fever and headache, but may occasionally be life-threatening or even fatal.