1. Faculty of Medicine “Manuel Fajardo”, 10400 Havana City, Cuba
2. Academic Paediatric Hospital “Pedro Borrás”, 10400 Havana City, Cuba
3. Carlos J. Finlay Hospital, 11500 Havana City, Cuba
4. Cuban Institute of Gastroenterology, 10400 Havana City, Cuba
5. National Institute of Hygiene, Epidemiology and Microbiology, 10300 Havana City, Cuba
6. Institute of Infectology “Emilio Ribas”, 04610-002 São Paulo, SP, Brazil
7. National Centre Coordinator of Clinical Trials, 11600 Havana City, Cuba