Human herpesviruses-6 and -7 infections

Purpose of review To summarize the biology and clinical consequences of infection with the closely related human herpesvirus-6 and 7 (HHV-6/7) in children. Recent findings Over the last year there has been a paucity of paediatric publications on HHV-6/7 and only two studies focused on HH7. Steady progress has been made regarding the biology and clinical consequences of HHV-6 infection whereas the effect of HHV-7 infection remains a neglected topic. However, both viruses have been shown to contribute significantly and equally to the burden of disease in young children with suspected enephalitis or severe convulsions with fever. There continues to be uncertainty as to the effects of HHV-6 infection after stem cell transplant, although there is general agreement that it contributes to encephalitis. In contrast, HHV-7 seems to have little clinical impact after stem sell transplant, although central nervous system infection and disease have recently been reported in children. Understanding the contribution of chromosomal integration and inheritance of both HHV-6 vrariants A and B (HHV 6A/B) and their effect on diagnosis is emerging. Summary There is an urgent need for more r4esearch on HHV-6 and -7 in children particularly in relation to chromosonal integration of HHV-6A and B, and clinical consequences of HHV-7 infection.