Shortly after hospital admission, progressive respiratory failure developed requiring intubation and mechanical ventilation. Due to profound hypoxemia, the ventilator was set to deliver 100% inspired oxygen and positive end-expiratory pressure of 15 cm H2O. Arterial blood gas analysis on these ventilator settings showed Po2 of 50 mm Hg. The patient was placed on paralytics while on the ventilator. Differential diagnosis included severe community-acquired pneumonia, acute interstitial pneumonia, alveolar hemorrhage, acute hypersensitivity pneumonitis, and acute eosinophilic pneumonia. Cardiogenic pulmonary edema was excluded by normal B-type natreuritic peptide and normal left ventricular systolic function on echocardiography. The patient was started empirically on ceftriaxone and azithromycin IV. Further workup revealed normal antinuclear antibody, erythrocyte sedimentation rate, and anti-neutrophil cytoplasmic antibody. Findings on blood culture, tracheal aspirate culture, and serology for infection were negative. Bronchoscopy with BAL was done. BAL return was not bloody. Total cell count of BAL was 11,300/μL and differential cell count showed 72% eosinophils (Fig 2
). BAL bacterial, viral, Legionella, Mycobacterial, and fungal culture findings were negative. Three samples of stool were negative for ova and parasites.