[1] Pasteur Inst Tunis, Dept Immunol, Tunis, Tunisia
[2] Tunis El Manar Univ, Tunis, Tunisia
[3] Red Cross War Mem Childrens Hosp, Paediat Infect Dis Unit, Cape Town, South Africa
[4] Univ Cape Town, Dept Paediat & Child Hlth, Cape Town, South Africa