Control of the inflammation in HSV encephalitis may improve outcome, as shown in mouse models of the disease.27–29 Before the availability of aciclovir, corticosteroids were sometimes used as a treatment in humans with HSV encephalitis,30 31 and more recently both cerebral oedema on imaging and CSF IL-6 levels were shown to be reduced in patients given corticosteroids.23 However, because corticosteroids cause immunosuppression, which in theory facilitates increased viral replication, their role is uncertain.32 The gene discussed is IL6; the disease is herpes simplex encephalitis.