An immigrant from Central America presents to the emergency room with complaints that he has not been feeling well for the past 2 weeks. He states that he was bitten by an insect while visiting family in Mexico. He has had flu-like symptoms, fever, malaise, anorexia, chills, anorexia and a headache for at least 14 days. Physical exam reveals a heart rate of 120, BP 110/70 and T 101.5. There is diffuse edema around the upper face. There appears to be a tender reddish nodule on the side of the neck. His CBC is elevated with a relative lymphocytosis. The blood smear is shown below. You believe that the patient has an acute pathology. What is the study that you will order next?
A. ECG
B. Lumbar puncture
C. Upper and lower endoscopy
D. Barium swallow