[1] Univ N Carolina, Dept Med, Div Infect Dis, Chapel Hill, NC 27515 USA
[2] Univ N Carolina, Inst Global Hlth & Infect Dis, Chapel Hill, NC 27515 USA
[3] Fred Hutchinson Canc Res Ctr, Vaccine & Infect Dis Div, 1124 Columbia St, Seattle, WA 98104 USA
[4] Univ Washington, Lab Med & Med, Seattle, WA 98195 USA