Reactivation of HSV-1 Encephalitis in an Infant Within One-Month of Completing Acyclovir Treatment: A Case Study

OBJECTIVE: Recurrent herpes simplex encephalitis (HSE) is a rare but reported complication. Current Infectious Disease Society of America (IDSA) guidelines of 21 days IV acyclovir and 6 months oral acyclovir are indicated to help prevent relapse. There is a case in the literature of HSV-2 causing recurrent HSE after completion of current IDSA guidelines, but no reports of HSV-1 doing the same. We present a case of an 8-month-old boy with HSV-1 encephalitis reactivation within one month of completing the current IDSA acyclovir recommendations.

METHODS: Chart review.

DISCUSSION: A 4-week-old boy presented with behavioral change, pallor, and seizure activity. An infectious evaluation revealed disseminated HSV-1 and he was treated with 21 days of IV acyclovir. Initial MRI showed small parenchymal lesions in the left frontal lobe, perirolandic cortex, and deep gray structures. After IV therapy, repeat MRI was stable and CSF was negative for HSV-1. He subsequently completed 6 months of oral acyclovir treatment per IDSA guidelines. Ten days after completing oral acyclovir treatment, he re-presented with acute fever, fatigue, and lip-smacking episodes. EEG confirmed seizures of right temporal region onset. Repeat MRI showed extensive cortical/subcortical lesions with leptomeningeal enhancement throughout the right cerebral hemisphere, prominently involving the temporal/insular cortex, and lesions in left temporal and insular region. CSF analysis demonstrated pleocytosis (129 cells/uL), elevated protein (77 mg/dL), and normal glucose (46 mg/dL). CSF was positive for HSV-1, consistent with recurrent HSV-1 encephalitis.

CONCLUSION: Although rare, recurrent HSE due to HSV-1 is possible despite completion of current IDSA acyclovir guidelines.
Keywords: Recurrent Herpes Simplex Encephalitis, HSV-1