[1] Ctr Dis Control & Prevent, Div STD Prevent, Natl Ctr HIV, Atlanta, GA 30333 USA
[2] Ctr Dis Control & Prevent, Div STD Prevent, Natl Ctr STD, Atlanta, GA 30333 USA
[3] Ctr Dis Control & Prevent, Div STD Prevent, Natl Ctr TB Prevent, Atlanta, GA 30333 USA
[4] Univ Michigan, Sch Publ Hlth, Dept Epidemiol, Ctr Mol & Clin Epidemiol Infect Dis, Ann Arbor, MI 48109 USA