1. Postgraduate Training Programme in Pediatrics, Department of Clinical and Experimental Medicine, University of Catania, Via S. Sofia 78, 95123 Catania, Italy
2. Infectious Diseases Unit, Department of Clinical and Experimental Medicine, ARNAS Garibaldi Hospital, University of Catania, 95122 Catania, Italy
3. Department of Clinical and Experimental Medicine, University of Messina, 98122 Messina, Italy
4. Department of Paediatrics, Sapienza University of Rome, Viale del Policlinico 155, 00161 Roma, Italy
5. Department of Clinical and Experimental Medicine, Section of Pediatrics and Child Neuropsychiatry, University Hospital “Policlinico G. Rodolico”, 95125 Catania, Italy