[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] Fred Hutchinson Canc Res Ctr, Div Publ Hlth Sci, Seattle, WA 98104 USA
[5] Fred Hutchinson Canc Res Ctr, Div Human Biol, Seattle, WA 98104 USA
[6] Univ Nairobi, Dept Med Microbiol, Nairobi, Kenya
[7] Coast Gen Prov Hosp, Mombasa, Kenya