A 61-year-old woman from Wisconsin presents 5 days after hiking in wooded terrain with fever (39.2°C), malaise, and confusion. Vital signs show HR 102/min, BP 128/82 mmHg, RR 18/min, SpO2 98% on room air. Laboratory studies reveal leukopenia (WBC 3.2 K/µL), thrombocytopenia (platelets 95 K/µL), and elevated transaminases (AST 156 U/L). Peripheral blood smear demonstrates intracellular morulae within neutrophils. Chest radiograph is unremarkable. Which organism is most likely responsible?

1. A)Plasmodium falciparum
2. B)Rickettsia rickettsii
3. C)Ehrlichia chaffeensis
4. D)Anaplasma phagocytophilumGABARITO
5. E)Borrelia burgdorferi