[1] Addenbrookes Hosp, Clin 1A, Cambridge CB2 2QQ, England
[2] Hlth Protect Agcy, Ctr Communicable Dis Surveillance, London NW9 5EQ, England
[3] Royal Hallamshire Hosp, Sheffield S10 2JF, S Yorkshire, England
[4] W Suffolk Hosp, Bury St Edmunds, Suffolk, England
[5] Brighton Hlth Care Trust, Brighton, E Sussex, England