A 90-year-old male from Missouri presented with a 3-day history of fever and dyspnea. His medical history included hypertension and splenectomy due to injury. He lived with his wife and reported no recent travel, pet or known tick exposure.
On admission, he was febrile (temperature 40˚C) and hypotensive (105/58). Laboratory values of note were elevated leukocytes (13,100 cells/mL; 58% neutrophils), decreased hemoglobin (9.5 g/dL), low platelet count (106,000 cells/mL), increase liver function tests (total bilirubin 3.2; alkaline phosphatase 45 units per liter; aspartate transaminase 1935 units per liter; alanine transaminase 872 units per liter). Chest radiographs on admission were clear, but repeat testing on the following day showed new right lung airspace opacities. Empiric antibiotics were begun with vancomycin and moxifloxacin, but he experienced increasing hypotension and dyspnea. Based on a suspicion for tickborne disease, an EDTA whole blood sample was submitted for microscopic examination and real-time PCR for Ehrlichia/Anaplasma and Babesia microti.
The Babesia microti PCR was negative, as well as a multiplex PCR for Ehrlichia ewingii, E. chaffeensis, and Anaplasma phagocytophilum, but the giemsa-stained, peripheral blood thin films showed the following (CLICK ON IMAGES TO ENLARGE):
Repeat Babesia microti PCR was still negative and malaria PCR (done for investigative purposes) was also negative.
What is your diagnosis? How would you further work up this case?