1. Department of Medicine, Brooke Army Medical Center , Fort Sam Houston, TX 78234, USA
2. Infectious Disease Service, Brooke Army Medical Center , Fort Sam Houston, TX 78234, USA
3. Emerging Infectious Diseases Branch, Walter Reed Army Institute of Research , Silver Spring, MD 20910, USA
4. Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. , Bethesda, MD 20817, USA