Human Ehrlichiosis (air-LICK-ee-oh-sis) is a disease caused by rickettsial type organisms that are transmitted in part by the same ticks that carry Lyme disease. The disease's name has been officially changed to Anaplasmosis, though Ehrlichoiosis will be in common use for some time. Ehrlichiosis usually presents with high fever, malaise, headache, myalgia, sweats, and nausea. Ehrlichiosis patients may have a low white blood cell count and low platelet count, as well as elevated liver enzymes. Some patients may get better on their own. Antibiotics that work for Lyme do not work against ehrlichiosis. Instead, doctors use drugs in the tetracycline family. Tetracycline drugs can be used against Lyme, so some doctors cover both bases by prescribing tetracycline when the diagnosis is unclear.
Patients diagnosed with Ehrlichia should also be tested for Lyme disease due to the fact that co-infections have been documented in several patients.
There are two forms of the disease caused by the Ehrlichia species: E. chaffeensis and E. phagocytophilia, which cause the human diseases, Human Monocytic Ehrlichiosis (HME) and Human Granulocytic Ehrlichiosis (HE), respectively. HME has been linked to the bites of Amblyomma Americanum (Lone Star Tick) and HE has been closely linked to the bites of Ixodes Scapularis and Ixodes Pacificus. The Dermacentor Variabilis (dog tick) has also been suggested in the transmission of both. Seroconversion usually occurs between two and four weeks after infection.
HME was first described in 1987 and confirmed in 30 states, predominately in the southeast and mid-atlantic states. HME has also been found in Europe and Africa.
HE originated in Minnesota and was first described in 1994. HE has been found in the upper midwestem states, northeastern states, and northern California.