[1] Univ Chile, Fac Med, Dept Pediat, Hosp Dr Luis Calvo Mackenna, Santiago, Chile
[2] Hosp Dr Luis Calvo Mackenna, Dept Pediat, Santiago, Chile
[3] Clin Las Condes, Lab Mol Biol, Santiago, Chile
[4] Hosp Dr Exequiel Gonzalez Cortes, Dept Pediat, Santiago, Chile
[5] Hosp Dr Roberto del Rio, Dept Pediat, Santiago, Chile
[6] Ohio State Univ, Div Pediat Infect Dis, Nationwide Childrens Hosp, Columbus, OH 43210 USA