A previously healthy 24-year-old man presented with a 2-day history of fever, myalgias, nausea, and vomiting. On the morning of hospital admission, cough and progressive dyspnea developed in the patient. He denied other symptoms, including chest pain, abdominal pain, or sore throat. This military recruit had been participating in field training in southern New Mexico for 2 weeks prior to presentation and had previously been living in Maricopa County, AZ. He lived in field barracks but denied sick contacts, and no other members of his unit were ill. He reported no contact with household or farm animals, rabbits, birds, or toxins, and he denied the use of illicit drugs.
Physical ExaminationAt presentation, he had a pulse rate of 130 beats/min, BP of 130/85 mm Hg, a respiratory rate of 36 breaths/ min, and a temperature of 39.3°C. The patient was alert but in moderate respiratory distress. Chest auscultation revealed bilateral rales in the middle and lower lung fields. The cardiac examination findings were normal except for tachycardia. There was no jugular venous distention, peripheral edema, skin rash, or nodules. The conjunctiva were normal.
Laboratory and Radiographic FindingsThe hemogram showed a WBC count of 24,400 cells/L, a hemoglobin concentration of 19 g/dL, and a platelet count of 89,000 cells/L. The manual differential count of peripheral blood leukocytes showed 66% segmented neutrophils, 22% band forms, 5% normal lymphocytes, and 5% atypical lymphocytes. Coagulation study findings and albumin concentration (3.7 g/dL) were normal; aspartate aminotransferase concentration was 76 IU/L, creatinine concentration was 1.3 mg/dL, and arterial blood gas measurements with the patient breathing room air showed the following: pH, 7.46; Pco 2 , 29 mm Hg; Po 2 , 47 mm Hg; and oxygen saturation, 77%.Chest radiographic findings revealed bilateral infiltrates involving all lung fields (Fig 1). A contrastenhanced CT scan of the chest showed no embolism;
