Human herpesvirus (HHV) -6 and -7 have been associated with a greater risk of developing CMV disease in transplant recipients [34] [35] [36] [37] . Furthermore, HHV-6 and HHV-7 have been shown to be significant contributors to morbidity and poor outcomes, particularly when concurrent infection with CMV exists [35, [38] [39] [40] . Thus, it is of interest to investigate whether the association between CMV and other herpes viruses exists in critically ill patients.