[1] Boston Univ, Sch Med, Sect Infect Dis, Boston, MA 02215 USA
[2] Tufts Univ, Sch Arts & Sci, Medford, MA 02155 USA
[3] Boston Med Ctr, Boston, MA USA
[4] Boston Univ, Sch Med, Dept Med Sci & Educ, Boston, MA 02118 USA
[5] Tufts Univ, Sch Med, Dept Publ Hlth & Community Med, Boston, MA 02111 USA