[1] Montreal Reg Publ Hlth Dept, Infect Dis Unit, Montreal, PQ H3H 1P8, Canada
[2] McGill Univ, McGill Aids Ctr, Montreal, PQ, Canada
[3] McGill Univ, Dept Epidemiol & Biostat, Montreal, PQ, Canada
[4] Univ Montreal, Hop St Justine, Ctr Maternel & Infantile, SIDA, Montreal, PQ H3T 1C5, Canada