[1] Childrens Hosp Los Angeles, Childrens Ctr Canc & Blood Dis, Los Angeles, CA 90027 USA
[2] Univ So Calif, Keck Sch Med, Dept Pediat, Los Angeles, CA 90033 USA
[3] Univ Nacl Asuncion, Inst Previs Social, Serv Oncol Pediat, Asuncion, Paraguay
[4] Univ Nacl Asuncion, Inst Nacl Canc, Serv Oncol Pediat, Asuncion, Paraguay
[5] Univ Nacl Asuncion, Hosp Clin San Lorenzo, Dept Hematooncol Pediat, Fac Med, Asuncion, Paraguay
[6] Hosp Univ Nino Jesus, Serv Hematooncol Pediat, Madrid, Spain
[7] St Jude Childrens Res Hosp, Dept Infect Dis, Memphis, TN 38105 USA
[8] St Jude Childrens Res Hosp, Dept Oncol, Memphis, TN 38105 USA
[9] St Jude Childrens Res Hosp, Int Outreach Program, Memphis, TN 38105 USA
[10] Univ Tennessee, Ctr Hlth Sci, Dept Pediat, Memphis, TN 38163 USA