[1] Univ Washington, Dept Epidemiol, UW Box 351619, Seattle, WA 98195 USA
[2] Publ Hlth Seattle & King Cty, HIV STD Program, Seattle, WA USA
[3] Univ Washington, Dept Med, Seattle, WA 98195 USA
[4] Univ Washington, Dept Biostat, Seattle, WA 98195 USA
[5] Fred Hutchinson Canc Res Ctr, 1124 Columbia St, Seattle, WA 98104 USA
[6] Univ Washington, Dept Microbiol, Seattle, WA 98195 USA
[7] Univ Washington, Dept Global Hlth, Seattle, WA 98195 USA