Immunologic factors may play a role in herpes simplex virus 1 reactivation in the brain and retina after influenza vaccination

Abstract

Herpes simplex virus 1 (HSV-1) is a nearly ubiquitous human pathogen, remaining dormant in its human host the majority of the time. The interaction between HSV-1 and the immune system represents a complicated balance of power that allows the virus to persist in the host for a lifetime. However, disruptions in the immune system can activate the virus with the potential to cause devastating infections in the central nervous system (CNS). We present a patient who suffered three consecutive yearly HSV-1 CNS episodes (encephalitis, seizure, and retinitis), each within days of his influenza vaccination. We highlight subtle immunologic defects in this patient that may have allowed unchecked viral replication and resultant disease manifestations, as well as the potential role of influenza vaccine in tipping this balance in favor of HSV-1.

Keywords: Acute retinal necrosis; Encephalitis; Herpes simplex; Influenza; Vaccination.

Fig. 1

Herpes simplex encephalitis. MRI brain at one month (top left, top right) and one year (bottom left, bottom right) following the initial presentation. T1 with contrast axial (top left) and coronal (top right) images taken one month after the initial presentation showing enhancement in the left temporal lobe and subinsular cortex as well as signal abnormality in the right and left insular cortices. T2 without contrast axial (bottom left) and coronal (bottom right) images taken at one year when the patient presented with transient recrudescence of his symptoms.

Fig. 2

Acute retinal necrosis. Fundus photograph (left) showing retinal whitening, vascular occlusion, numerous retinal hemorrhages and disc edema. Flourescein angiogram (right) showing leaking and staining of the central retinal arterioles and venules and severe peripheral nonperfusion consistent with occlusive vasculitis.