1. Center for Tropical Diseases, Institute for Human Infections & Immunity, University of Texas Medical Branch, Galveston, TX, USA
2. Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA
3. Comision Mexico-Estados Unidos para la Prevencion de la Fiebre Aftosa & Otras Enfermedades Exoticas de los Animales, Mexico City, Mexico
4. Instituto Nacional de Salud, Bogota, Colombia