[1] Univ Amsterdam, Acad Med Ctr Amsterdam, Ctr Trop Med & Travel Med, Amsterdam, Netherlands
[2] Red Cross War Mem Childrens Hosp, Dept Paediat & Child Hlth, Cape Town, South Africa
[3] Red Cross War Mem Childrens Hosp, MRC Unit Child & Adolescent Hlth, Cape Town, South Africa
[4] Bristol Royal Hosp Children, Dept Paediat Radiol, Bristol, Avon, England
[5] Univ Bristol, Bristol, Avon, England