1. Laboratory of Virology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
2. Department of Pediatrics, University of Brescia, Italy
3. Pediatrics Unit, University of Siena, Italy
4. Epidemiologie Moleculaire des Enterovirus, Institut Pasteur, Paris, France
5. NIBSC, Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK