aUCD Centre for Experimental Pathogen Host Research (CEPHR), School of Medicine, University College Dublin

bSt Vincents University Hospital, Elm Park, Dublin 4, Ireland

cDepartment of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA

Correspondence to Rachel MacCann, MB, BCh, BAO, LRCPI & SI, MRCPI, UCD Centre for Experimental Pathogen Host Research (CEPHR), School of Medicine, University College Dublin, Belfield, Dublin 4, Ireland. Tel: +353 1 22 13464; e-mail: [email protected]