Ehrlichiosis: a cause of bone marrow hypoplasia in humans.

Infection with Ehrlichia canis should be suspected in patients with fever, headache, malaise, leukopenia, thrombocytopenia, and a history of recent exposure to ticks. The cytopenia is caused by bone marrow hypoplasia which may be severe. The disease may be confused with spotless Rocky Mountain spotted fever but can be differentiated from this infection serologically with acute and convalescent sea. In humans, recovery has occurred with and without antibiotic therapy. However, prompt antibiotic therapy is advised prior to serologic studies, especially in immunocompromised individuals, splenectomized persons, and patients with AIDS-who may develop a more overwhelming rickettsial infection.