[1] Walter Reed Natl Mil Med Ctr, Dept Med, Bethesda, MD USA
[2] Uniformed Serv Univ Hlth Sci, Infect Dis Clin Res Program, Div Prevent Med, Rockville, MD 20852 USA
[3] Naval Med Ctr San Diego, Div Infect Dis, Dept Med, San Diego, CA USA
[4] Dept Def Armed Forces Hlth Surveillance Ctr, Silver Spring, MD USA