Failure of acyclovir sodium therapy in herpes simplex encephalitis

Herpes simplex encephalitis is an important disease characterized by focal haemorrhagic necrosis of the temporal and frontal lobes of the brain. The mortality rate may be as high as 70% of untreated cases. Isolation of the virus from brain tissue is the most reliable means of diagnosis. Although some non-invasive diagnostic modalities have been investigated, none is as reliable as brain tissue sampling. Despite acceptance that acyclovir sodium is the most effective drug for treatment, there is not a consensus on the dosage and duration of the antiviral therapy because some patients fail to respond and sometimes there is recurrence following therapy. We report a case of encephalitis in a previously normal host who died after a 13-day course of acyclovir therapy with isolation of HSV-type 1 from the brain post mortem.