[1] Univ Cape Town, Div Human Genet, Inst Infect Dis & Mol Med, Fac Hlth Sci, ZA-7925 Cape Town, South Africa
[2] Univ Zimbabwe, Dept Immunol, Harare, Zimbabwe
[3] Univ Zimbabwe, Fac Hlth Sci, Dept Paediat, Harare, Zimbabwe
[4] Letten Fdn Res House, Harare, Zimbabwe
[5] Univ Oslo, Rikshosp, Div Obstet & Gynaecol, N-0027 Oslo, Norway
[6] Univ Zimbabwe, Dept Chem Pathol, Harare, Zimbabwe