A process for treating a patient with leukemia or an aplastic anemia having cells with inclusions that stain with anti-E. canis antibodies or antibodies to other Ehrlichia or Anaplasma is disclosed. That process comprises administering to the patient (i) an antibacterial amount of a rifamycin, (ii) an antibacterial amount of a quinolone, or a mixture of (i) and (ii).
