1. From the Epidemic Intelligence Service, Division of Applied Public Health Training, Epidemiology Program Office, Centers for Disease Control and Prevention, Atlanta, Georgia, and
2. Office of Genetics and Disease Prevention, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, and
3. Cystic Fibrosis Foundation, Bethesda, Maryland and
4. University of Wisconsin Hospital and Clinics, Madison, Wisconsin.