1. Hospital Universitario Fundacion Alcorcon, Calle Budapest 1, 28922 Madrid, Spain
2. Instituto de Medicina Tropical “Alexander von Humboldt”, Universidad Peruana Cayetano Heredia, Lima 31, Peru
3. Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
4. ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic, Universitat de Barcelona, 08036 Barcelona, Spain