1. Department of Respiratory Disease, Hospital Nacional Guillermo Almenara Irigoyen, Lima, PERU
2. Department of Pathology, Hospital Nacional Guillermo Almenara, Lima, PERU
3. South American Center for Research in Education and Public Health, Universidad Norbert Wiener, Lima, PERU
4. Department of Pathology, Hospital Nacional Docente Madre Niño San Bartolomé, Lima, PERU