1. Royal College of Paediatrics and Child Health, London, United Kingdom;
2. Communicable Disease Surveillance Centre, London, United Kingdom;
3. Birmingham Children's Hospital, Birmingham, United Kingdom;
4. Health Protection Agency Centre for Infections, London, United Kingdom;
5. Western General Hospital, Edinburgh, United Kingdom;
6. Scottish Centre for Infection and Environmental Health, Glasgow, United Kingdom;
7. The Children's Hospital, Dublin, Ireland