2 Bandim Health Project, Indepth Network, Bissau, Guinea-Bissau; Research Centre for Vitamins and Vaccines, Bandim Health Project, Statens Serum Institut, 2300 Copenhagen, Denmark.
3 Department of Paediatrics, Kolding Hospital, Kolding, Denmark.
4 Research Centre for Vitamins and Vaccines, Bandim Health Project, Statens Serum Institut, 2300 Copenhagen, Denmark.