[1] Royal Free Hampstead NHS Trust, Dept Virol, London NW3 2QG, England
[2] UCL, Sch Med, London NW3 2QG, England
[3] Komfo Anokye Teaching Hosp, Dept Med, Kumasi, Ghana
[4] James Cook Univ Hosp, Dept Infect & Travel Med, Middlesbrough, Cleveland, England
[5] Univ Cologne, Inst Virol, Cologne, Germany
[6] Kwame Nkrumah Univ Sci & Technol, Sch Med Sci, Kumasi, Ghana