[1] Univ Lille 2, Inst Pasteur, INSERM, U744, Lille, France
[2] Univ Strasbourg, Fac Med, Lab Epidemiol & Sante Publ, Strasbourg, France
[3] Univ Paris Sud 11, INSERM, U780, Villejuif, France
[4] Univ Toulouse 3, Fac Med, INSERM, U558, F-31062 Toulouse, France