1. Internal Medicine Service, Department of Medicine, Brooke Army Medical Center, San Antonio, TX 78234, USA
2. Pulmonary & Critical Care Medicine Service, Department of Medicine, Brooke Army Medical Center, San Antonio, TX 78234, USA
3. J-7 Education & Training Directorate, Defense Health Agency, Falls Church, VA 22042-5101, USA
4. Infectious Disease Service, Department of Medicine, Brooke Army Medical Center, San Antonio, TX 78234, USA