[1] Univ Washington, Dept Epidemiol, Seattle, WA 98104 USA
[2] Univ Washington, Dept Med, Seattle, WA 98104 USA
[3] Univ Washington, Dept Biostat, Seattle, WA 98104 USA
[4] Univ Washington, Dept Lab Med, Seattle, WA 98104 USA
[5] Fred Hutchinson Canc Res Ctr, Div Human Biol, Seattle, WA 98104 USA
[6] Coast Prov Gen Hosp, Mombasa, Kenya
[7] Univ Nairobi, Dept Med Microbiol, Nairobi, Kenya