Q. A 6-year-old male initially presented to an outside hospital two weeks ago with complaints of cough, dyspnea, wheezing, and intermittent fever for three days. He was admitted and diagnosed with community-acquired pneumonia. Following appropriate treatment, he was discharged and despite improvement, his cough persisted for several weeks. He was readmitted to your facility three days ago for evaluation of his asthma and persistent cough. On admission, he was generally non-toxic appearing, though chest auscultation revealed coarse polyphonic rhonchi, especially on the upper zone of the left lung. A chest x-ray demonstrated a unilateral patchy consolidation of the left upper lung field. Evaluation of his peripheral blood smear demonstrated a mounting eosinophilia which had risen from 4 percent to 8 percent since his last admission two weeks ago, and his IgE was found to be 400 IU/mL. Yesterday, the patient coughed up a substance by sputum expectoration (see image) that was sent for culture and microscopic evaluation. Today, the patient’s symptoms have markedly improved and he has no new complaints. Based on the information you have at this point, what is the most likely underlying etiology of this patient’s symptoms?