[1] Washington Univ, Div Infect Dis, Sch Med, 4523 Clayton Ave,Campus Box 8051, St Louis, MO 63110 USA
[2] Washington Univ, Dept Pediat, St Louis, MO 63110 USA
[3] Washington Univ, Bernard Becker Med Lib, St Louis, MO 63110 USA
[4] Washington Univ, Sch Med, Div Publ Hlth Sci, St Louis, MO 63110 USA