1. Department of Medicine, University of Iowa Hospitals and Clinics , Iowa City, IA 52242, USA
2. Department of Family Medicine, Womack Army Medical Center , Fort Liberty, NC 28310, USA
3. Department of Family, Community, and Preventive Medicine, Drexel University College of Medicine , Philadelphia, PA 19104, USA
4. Department of Research and Medical Education, Campbell University, Jerry M. Wallace School of Osteopathic Medicine , Lillington, NC 27546, USA
5. Department of Allergy and Immunizations, Lackland Air Force Base , San Antonio, TX 78236, USA