Acknowledgements
We thank all children and their families for their participation in the study; the field workers, field supervisors, Mauricio H. Rodríguez at the CISM laboratory and other staff at CISM for their work during the study; Laura Puyol, Diana Barrios and Pau Cisteró for laboratory support; John J. Aponte for contribution to study design; Sonia Tomàs for project management.