Tickborne zoonosis caused by obligate intracellular gram-negative bacteria in the family Anaplasmataceae.
Infection that occurs in the southeast and south central U.S. and is transmitted by the Lone Star tic, Amblyomma americanum.
Annual rate 31 cases per 100,000 persons.
Incubation period of 5 days and associated with fever, headache, malaise, nausea, vomiting and myalgia.
Severe disease may be associated with GI, renal, respiratory and CNS involvement, and rarely death.
Caused primarly by infection with Ehrlichia chaffeensis, which infects monocytes, and less commonly E.ewingii, which infects granulocytes.
Patients often have leukopenia, anemia, and thrombocytopenia.
The erythrocyte sedimentation rate (ESR) is minimally elevated and levels of serum transaminases may be mildly increased.
Up to 36% of patients present with a rash.
Skin involvement is most common in children and may manifest as macules, papules, petechiae, erythema, and edema of the hands and feet.