Participants will be admitted to either the NIH Clinical Center in Bethesda, Maryland, the Texas Center for Infectious Diseases in San Antonio or the South Texas Hospital or Valley Baptist Hospital, both in Harlingen, Texas. On admission, patients will have a medical history, physical examination, blood and urine tests, sputum culture, X-rays, pulmonary function tests and a computed tomography (CT) scan. CT produces 3-dimensional images of body tissues and organs in small sections. For the procedure, the patient lies still on a table surrounded by the scanner.