1. Dermatology Unit; Department of Specialistic, Diagnostic and Experimental Medicine; S. Orsola-Malpighi Hospital; University of Bologna; Bologna Italy
2. Pediatric Unit; Department of Medical and Surgical Sciences; S. Orsola-Malpighi Hospital; University of Bologna; Bologna Italy
3. Department of Dermatology and Allergy; Ludwig-Maximilian University; Munich Germany
4. Department of Specialistic; Diagnostic and Experimental Medicine; Operative Unit of Clinical Microbiology; Laboratory of Virology; S. Orsola-Malpighi Hospital; University of Bologna; Bologna Italy