1. Sustainable Sciences Institute, Managua 14006, Nicaragua.
2. Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI 48109, USA.
3. Viral Epidemiology and Immunity Unit, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-3203, USA.
4. Division of Infectious Diseases and Vaccinology, School of Public Health, University of California, Berkeley, Berkeley, CA 94720-3370, USA.
5. Laboratorio Nacional de Virología, Centro Nacional de Diagnóstico y Referencia, Ministerio de Salud, Managua 14062, Nicaragua.
6. Centro de Salud Sócrates Flores Vivas, Ministerio de Salud, Managua 12037, Nicaragua.