[1] Derriford Univ Hosp, Dept Hepatol, Plymouth, Devon, England
[2] Derriford Univ Hosp, Dept Microbiol, Plymouth, Devon, England
[3] Hlth Protect Agcy, Ctr Infect, Virus Reference Dept, London, England
[4] Royal Cornwall Hosp, Gastrointestinal Unit, Truro, England