[1] Dalarna Univ, Sch Hlth & Welf, Falun, Sweden
[2] Uppsala Univ, Dept Womens & Childrens Hlth, Uppsala, Sweden
[3] Univ Kinshasa, Kinshasa Sch Publ Hlth, Kinshasa, DEM REP CONGO
[4] Univ Buea, Fac Sci, Dept Microbiol & Parasitol, Buea, Cameroon
[5] Karolinska Inst, Dept Womens & Childrens Hlth, Stockholm, Sweden